1 00:00:01,200 --> 00:00:05,680 We're doctors, brothers, and twins, and we both love to eat, 2 00:00:05,680 --> 00:00:09,800 but which is worse for us - fat or sugar? 3 00:00:13,880 --> 00:00:16,640 It's the hottest question in nutrition right now, 4 00:00:16,640 --> 00:00:20,160 with sugar in particular being targeted as public enemy no 1. 5 00:00:21,960 --> 00:00:25,240 Sugar is the thing that's making you specifically sick. 6 00:00:27,160 --> 00:00:30,520 We're going to find out if too much sugar or too much fat 7 00:00:30,520 --> 00:00:35,320 can make you sick or pile on the pounds. 8 00:00:35,320 --> 00:00:37,160 You're a quarter fat! 9 00:00:39,600 --> 00:00:43,240 One of us is going on an extreme high fat diet. 10 00:00:43,240 --> 00:00:46,760 This is Tiger. Tiger is basically on my diet. 11 00:00:47,880 --> 00:00:50,240 The other, on an extreme high sugar one. 12 00:00:50,240 --> 00:00:52,200 None of these foods have any fat, do they? 13 00:00:52,200 --> 00:00:54,000 It's a high-carb, sugary diet. 14 00:00:56,880 --> 00:01:00,760 During these month-long diets, we'll be testing how our minds... 15 00:01:00,760 --> 00:01:02,040 I bought loads of them! 16 00:01:03,120 --> 00:01:08,200 ..and our bodies cope with just eating fat or sugar. 17 00:01:08,200 --> 00:01:09,720 I feel like I'm out of juice. 18 00:01:09,720 --> 00:01:13,440 And what we discover is really surprising and really unsettling. 19 00:01:15,240 --> 00:01:17,960 It overturns my entire way of how I think about my body. 20 00:01:17,960 --> 00:01:19,160 I'm not well! 21 00:01:22,040 --> 00:01:23,880 But after meeting this scientist 22 00:01:23,880 --> 00:01:27,960 and some cheesecake-eating rats, we found that the latest 23 00:01:27,960 --> 00:01:34,240 scientific research changed what we thought we knew about fat and sugar. 24 00:01:34,240 --> 00:01:37,960 Total opposite of I think what we would expect, 25 00:01:37,960 --> 00:01:39,440 what most doctors would expect, 26 00:01:39,440 --> 00:01:41,880 what most people in the street would expect. 27 00:01:43,000 --> 00:01:46,200 And it has the potential to do the same for you. 28 00:02:09,280 --> 00:02:11,400 I'm Dr Chris van Tulleken, 29 00:02:11,400 --> 00:02:14,400 and I'm a specialist in infectious disease. 30 00:02:19,360 --> 00:02:23,200 Here in Britain, fat's traditionally been seen as the major problem. 31 00:02:24,600 --> 00:02:27,520 When I trained as a doctor it was clear that fat was the enemy 32 00:02:27,520 --> 00:02:29,080 because it raises your cholesterol 33 00:02:29,080 --> 00:02:32,720 and it blocks up your arteries, causing strokes and heart attacks. 34 00:02:35,560 --> 00:02:39,000 Over in America, it's sugar that's under attack. 35 00:02:41,480 --> 00:02:45,920 I'm Dr Xand van Tulleken and my speciality is in tropical medicine. 36 00:02:52,240 --> 00:02:55,040 Now, in the States, sugar isn't just regarded as unhealthy - 37 00:02:55,040 --> 00:02:57,080 some people are even calling it toxic. 38 00:03:00,480 --> 00:03:02,480 So, who's right? 39 00:03:02,480 --> 00:03:07,440 It's a question that's fascinated us as doctors, and by a quirk 40 00:03:07,440 --> 00:03:11,280 of birth, we have a head start in getting to grips with it. 41 00:03:12,760 --> 00:03:14,760 Chris and I are identical twins, 42 00:03:14,760 --> 00:03:16,520 which means we're genetically the same, 43 00:03:16,520 --> 00:03:20,840 so we're in a really nice position to do an experiment on each other. 44 00:03:20,840 --> 00:03:23,080 Now, I live in New York so I get constant messages 45 00:03:23,080 --> 00:03:25,760 in the media about how fat is good for you and sugar is 46 00:03:25,760 --> 00:03:30,360 really the enemy, so I'm going to go on a high fat, low sugar diet. 47 00:03:30,360 --> 00:03:32,800 And although in Britain we do get this message, 48 00:03:32,800 --> 00:03:36,280 it's not as pervasive, and I'm convinced if I go on a low fat, 49 00:03:36,280 --> 00:03:38,760 high sugar diet, I will stay healthy. 50 00:03:38,760 --> 00:03:42,800 So who's right? The Americans who think that sugar is really toxic? 51 00:03:42,800 --> 00:03:45,600 Or the British, who think that fat is the deadly ingredient? 52 00:03:52,120 --> 00:03:55,800 We're going on extreme diets based on the sort of techniques used 53 00:03:55,800 --> 00:03:57,240 in scientific research, 54 00:03:57,240 --> 00:04:01,280 although we are a rather unscientific sample of just two. 55 00:04:03,720 --> 00:04:05,760 We want to know what they do to your weight and how 56 00:04:05,760 --> 00:04:09,600 they affect lifestyle diseases like heart problems and diabetes. 57 00:04:10,720 --> 00:04:13,600 Nutritionist Amanda Ursell is on hand to make sure 58 00:04:13,600 --> 00:04:17,560 we get it right, and that it's edible. 59 00:04:17,560 --> 00:04:19,280 If we kick off with Chris. 60 00:04:19,280 --> 00:04:21,800 Chris, you are on the high sugar diet. Yeah. I can see that. 61 00:04:21,800 --> 00:04:24,040 People tend to think of sugar as this, 62 00:04:24,040 --> 00:04:27,480 the white stuff in the bowl, but actually all of this food 63 00:04:27,480 --> 00:04:29,880 ultimately gets broken down into blood sugar. 64 00:04:29,880 --> 00:04:33,400 So, you are allowed bread and bagels, pasta, rice, 65 00:04:33,400 --> 00:04:35,480 potatoes, any description of breakfast cereals. 66 00:04:35,480 --> 00:04:38,280 And what's this? That's, er, a fizzy drink. 67 00:04:38,280 --> 00:04:40,080 And you can have some fruit and veg. 68 00:04:40,080 --> 00:04:42,160 Well, you can have unlimited fruit and veg. 69 00:04:42,160 --> 00:04:45,720 And they've all got sugar and none of these... these foods have any fat, do they? 70 00:04:45,720 --> 00:04:50,040 It's designed to be very low fat and it's a high carb sugary diet, 71 00:04:50,040 --> 00:04:52,280 and that's what you can live on for the next month. 72 00:04:52,280 --> 00:04:54,960 For Xand, this is your bit here. 73 00:04:54,960 --> 00:04:58,160 Basically, you can have cheese, you can have meat, you can 74 00:04:58,160 --> 00:05:01,200 have steak, you can have burgers, it's chicken with the skin on, 75 00:05:01,200 --> 00:05:04,440 you can have double cream in your coffee, you can have mayonnaise... 76 00:05:04,440 --> 00:05:07,400 The kind of thing you would do. But you're not allowed any fruit, 77 00:05:07,400 --> 00:05:09,960 and you're not allowed very much of this veggie stuff at all. 78 00:05:09,960 --> 00:05:13,600 My problem is that I'm not going to have a poo for a month, am I? 79 00:05:13,600 --> 00:05:15,320 Well, there are disadvantages. 80 00:05:15,320 --> 00:05:17,440 Firstly, your girlfriend doesn't want to kiss you 81 00:05:17,440 --> 00:05:18,680 because you have bad breath. 82 00:05:18,680 --> 00:05:20,320 Constipation, yes, you're right. 83 00:05:20,320 --> 00:05:22,520 I'm getting almost no fibre in any of this, am I? 84 00:05:22,520 --> 00:05:23,720 Very limited fibre. 85 00:05:23,720 --> 00:05:26,600 I think I'm going to be craving a bowl of fresh greens 86 00:05:26,600 --> 00:05:28,240 by the end of a few days. 87 00:05:28,240 --> 00:05:29,240 I'm sure you are. 88 00:05:35,120 --> 00:05:38,040 What do you think, Xand? I mean, I feel like you got the better deal. 89 00:05:38,040 --> 00:05:39,960 It's difficult cos I'm going to have bad breath 90 00:05:39,960 --> 00:05:41,200 and I'm not going to poo. Mm. 91 00:05:41,200 --> 00:05:43,880 But I get to have bacon and eggs for breakfast. 92 00:05:43,880 --> 00:05:47,960 Just to be absolutely clear, we can both eat as much as we want 93 00:05:47,960 --> 00:05:49,840 of the things on our bit of the table? 94 00:05:49,840 --> 00:05:51,760 Yeah. That's what we want you to do. 95 00:06:02,360 --> 00:06:05,200 These diaries are going to be quite hard to stick to, 96 00:06:05,200 --> 00:06:06,680 so we're going to film them. 97 00:06:06,680 --> 00:06:09,400 We're going to make video diaries using our phones. 98 00:06:09,400 --> 00:06:13,320 So at least for the duration of the video diaries, Xand won't be able 99 00:06:13,320 --> 00:06:15,600 to be shovelling carbohydrate into his mouth. 100 00:06:15,600 --> 00:06:20,000 Just woken up, and what I feel like is a massive stack of pancakes, 101 00:06:20,000 --> 00:06:21,920 with maple syrup. 102 00:06:21,920 --> 00:06:25,880 The point is, if I have to tell into my phone every day 103 00:06:25,880 --> 00:06:29,040 what the experience is, I can't lie. 104 00:06:29,040 --> 00:06:33,040 Keeps us honest. Yeah. That's the plan. 105 00:06:33,040 --> 00:06:36,640 What we're going to do now is sample how much oxygen your body consumes. 106 00:06:41,360 --> 00:06:44,800 Food is, of course, the fuel that powers our bodies. 107 00:06:44,800 --> 00:06:50,280 But just how it does that is subject to complex metabolic processes. 108 00:06:53,440 --> 00:06:59,200 Dr Richard MacKenzie studies how these processes influence diseases like diabetes. 109 00:07:00,880 --> 00:07:04,280 It's long been thought that eating too much fat can make us fatter, 110 00:07:04,280 --> 00:07:08,440 and that saturated fat can raise our cholesterol. 111 00:07:08,440 --> 00:07:11,040 High amounts of cholesterol are quite bad for us. 112 00:07:11,040 --> 00:07:14,360 They block our arteries and that blocks blood supply 113 00:07:14,360 --> 00:07:15,840 to the brain and heart, 114 00:07:15,840 --> 00:07:17,920 so that's quite dangerous. 115 00:07:17,920 --> 00:07:21,720 Eating or drinking sugar, on the other hand, releases insulin, 116 00:07:21,720 --> 00:07:24,880 a hormone that regulates our blood sugar. 117 00:07:24,880 --> 00:07:27,360 Eating too much sugar can make us fat, 118 00:07:27,360 --> 00:07:29,680 and could potentially lead to diabetes. 119 00:07:30,880 --> 00:07:34,760 We're going to be checking to see if our cholesterol and insulin levels 120 00:07:34,760 --> 00:07:38,000 go up or down over the next month. 121 00:07:38,000 --> 00:07:40,840 What's nice about this experiment, it's not a big experiment, 122 00:07:40,840 --> 00:07:42,360 but we're well-controlled, 123 00:07:42,360 --> 00:07:46,360 and so we really should get a robust answer from this. Yeah. 124 00:07:46,360 --> 00:07:49,880 OK, gentlemen, what I need you to do is to pop behind the curtains 125 00:07:49,880 --> 00:07:53,640 and strip down into your boxer shorts, please. 126 00:07:53,640 --> 00:07:57,480 We're expecting these diets to have an impact on our bodies. 127 00:07:57,480 --> 00:08:00,960 And one thing we're focusing on are changes not to just to fat, 128 00:08:00,960 --> 00:08:02,000 but also to muscle. 129 00:08:05,040 --> 00:08:07,480 Shifting fat is good, but losing muscle isn't healthy. 130 00:08:07,480 --> 00:08:09,880 You do look very different to when I last saw you, 131 00:08:09,880 --> 00:08:11,560 and I must look different as well. 132 00:08:11,560 --> 00:08:14,400 Yeah, you've got a little bit fatter. 133 00:08:14,400 --> 00:08:17,840 The first time in a few years we look a bit like twins. 134 00:08:17,840 --> 00:08:20,240 OK, gents, we'll just go for the bod pod now, 135 00:08:20,240 --> 00:08:22,280 I can see you're both a little cold. 136 00:08:22,280 --> 00:08:23,480 It's freezing in here. 137 00:08:23,480 --> 00:08:24,920 I feel a bit underdressed. 138 00:08:26,920 --> 00:08:29,200 MACHINE: It is important to remove any jewellery, 139 00:08:29,200 --> 00:08:31,160 shoes or eyeglasses before weighing. 140 00:08:31,160 --> 00:08:32,720 Here we go. 141 00:08:32,720 --> 00:08:36,320 Enter the bod pod, then close the door to begin test. 142 00:08:39,440 --> 00:08:43,120 This machine measures the ratio of fat to muscle. 143 00:08:43,120 --> 00:08:46,680 So Richard, we know that being fat isn't good for you, but why do 144 00:08:46,680 --> 00:08:50,320 we need all this fancy equipment to measure it so precisely? 145 00:08:50,320 --> 00:08:53,760 It's to help improve our understanding of exactly what 146 00:08:53,760 --> 00:08:57,040 increased body fat is doing, and we know that it's 147 00:08:57,040 --> 00:09:00,320 linked to a number of diseases that reduce our life expectancy. 148 00:09:00,320 --> 00:09:03,520 So things like cancer, diabetes, heart disease, strokes, 149 00:09:03,520 --> 00:09:05,760 hypertension, to name just a few, 150 00:09:05,760 --> 00:09:08,000 all are related to an increase in body fat. 151 00:09:10,040 --> 00:09:13,680 It's the same noise as the Batmobile canopy coming out. Mm. 152 00:09:13,680 --> 00:09:15,200 Close the door to begin test. 153 00:09:18,160 --> 00:09:21,000 And now we freeze him and send him into outer space. 154 00:09:21,000 --> 00:09:22,240 Yeah, that's the plan. 155 00:09:23,840 --> 00:09:27,120 So we've got the results from the body composition test. 156 00:09:27,120 --> 00:09:29,960 So can we try and guess? Before you tell us, can we try and guess? 157 00:09:29,960 --> 00:09:33,000 Please do. I think I'm 25%. 158 00:09:35,440 --> 00:09:38,880 I feel like someone who almost a quarter of their body is fat, 159 00:09:38,880 --> 00:09:40,000 that's how I feel. 160 00:09:42,280 --> 00:09:47,240 You're pretty much spot-on, you're 26.7% body fat. 161 00:09:47,240 --> 00:09:49,640 Spot-on, but slightly more than spot-on. 162 00:09:50,880 --> 00:09:53,680 Good news for Chris is, he's 22% body fat. 163 00:09:53,680 --> 00:09:56,240 Oh, so we're pretty similar. Oh, that's quite good, actually. 164 00:09:56,240 --> 00:09:58,760 I mean I think, you know, there is going...you know, he... 165 00:09:58,760 --> 00:10:02,880 So am I overweight? Um, well, we'd have to look at your BMI for that. 166 00:10:02,880 --> 00:10:04,680 Don't pull the punch. Yes. 167 00:10:04,680 --> 00:10:06,920 A little. You're a quarter fat! 168 00:10:06,920 --> 00:10:10,360 Look, Richard's being so nice about it! "A little, 169 00:10:10,360 --> 00:10:12,480 "I mean, we couldn't - we'd need to look at the chart." 170 00:10:12,480 --> 00:10:15,040 All right, all right, I get the message, I get the message. 171 00:10:15,040 --> 00:10:16,840 And he's OK, is he? A fraction over, 172 00:10:16,840 --> 00:10:20,720 um, but certainly on the healthier side of 20, 22.6%. 173 00:10:20,720 --> 00:10:21,960 I'm letting you down. 174 00:10:21,960 --> 00:10:23,840 You're letting your genes down. 175 00:10:23,840 --> 00:10:25,160 Yeah, sorry about that. 176 00:10:29,240 --> 00:10:34,800 I'm eating a little piece of turkey rolled up in a piece of cheese. 177 00:10:34,800 --> 00:10:37,360 I'm eating everything with my fingers now! 178 00:10:43,880 --> 00:10:46,600 We're two weeks into the diets, and we now want to start 179 00:10:46,600 --> 00:10:49,760 measuring how fat and sugar are affecting our bodies. 180 00:10:54,080 --> 00:10:56,960 And the place we want to start is with our brains. 181 00:10:58,640 --> 00:11:01,560 Everything goes through your brain, every decision you make, 182 00:11:01,560 --> 00:11:03,160 every action you take. 183 00:11:03,160 --> 00:11:04,880 So it'd be pretty important to know 184 00:11:04,880 --> 00:11:09,080 if cutting out fat or sugar affected how well your brain worked. 185 00:11:20,120 --> 00:11:23,520 At some point, we've all felt the pressure of mental stress 186 00:11:23,520 --> 00:11:27,960 and tension, but how does what you eat effect how you deal with it? 187 00:11:31,560 --> 00:11:35,040 And there are fewer more cognitively demanding environments 188 00:11:35,040 --> 00:11:36,720 than a city day trading room. 189 00:11:39,720 --> 00:11:44,000 So, we're going to put our diets to an extreme mental test 190 00:11:44,000 --> 00:11:46,040 by becoming stock traders for the day. 191 00:11:48,080 --> 00:11:51,280 Chris, on his high sugar diet, is in London, 192 00:11:51,280 --> 00:11:55,360 and I'm on my high fat diet in New York. 193 00:11:56,800 --> 00:12:00,640 So Chris, do you have any sense that you're going to be any good at this? 194 00:12:00,640 --> 00:12:02,040 It is like the Matrix. 195 00:12:02,040 --> 00:12:04,760 I'm looking at a financial horror show, this is just a mess. 196 00:12:04,760 --> 00:12:06,760 I mean, no wonder the economy collapsed. 197 00:12:06,760 --> 00:12:08,880 How could anyone understand? 198 00:12:08,880 --> 00:12:12,040 OK, so that we have a bit of help, JJ is going to give us a hand, OK? 199 00:12:12,040 --> 00:12:15,480 JJ. Hey, Chris, you've got to have a better attitude going in, buddy, 200 00:12:15,480 --> 00:12:17,200 you're a smart guy, it's not that hard. 201 00:12:17,200 --> 00:12:19,120 X axis, Y axis, it's... 202 00:12:19,120 --> 00:12:21,400 It's buy high, sell low, yeah? 203 00:12:21,400 --> 00:12:23,000 Er, buy low, sell high. 204 00:12:23,000 --> 00:12:24,000 The other way. 205 00:12:25,600 --> 00:12:28,920 OK, trade, and right there you see a bid. 206 00:12:28,920 --> 00:12:33,160 After a quick lesson with JJ, we're let loose on US-based 207 00:12:33,160 --> 00:12:37,640 TD Ameritrade's paper money application, and we've got 208 00:12:37,640 --> 00:12:41,480 100,000 dollars of pretend money to play with. 209 00:12:41,480 --> 00:12:42,720 Yeah. 210 00:12:42,720 --> 00:12:45,160 It was a pleasure, guys. Chris, good luck. Xand, good luck. 211 00:12:45,160 --> 00:12:47,200 May the best twin win. 212 00:12:47,200 --> 00:12:50,040 Right. And thank you very much, fellas. 213 00:12:54,200 --> 00:12:55,480 I can buy a bit of that. 214 00:12:55,480 --> 00:12:57,560 I'm going to buy some more companies now. 215 00:12:57,560 --> 00:12:59,720 I'm into it now. 216 00:12:59,720 --> 00:13:02,840 Ten of oil, light sweet crude. 217 00:13:02,840 --> 00:13:07,480 If the oil comes up then I will have made a bunch of money. 218 00:13:09,120 --> 00:13:12,960 OK, so now the pressure's on cos I've spent all my money. 219 00:13:12,960 --> 00:13:17,120 'Watching closely in the background is Professor Robin Kanarek. 220 00:13:17,120 --> 00:13:19,880 'She studies the effects of diet on cognition, 221 00:13:19,880 --> 00:13:22,520 'and she thinks I might be in for a hard time.' 222 00:13:25,760 --> 00:13:27,960 Don't know what any of this means. 223 00:13:27,960 --> 00:13:31,640 This is an extraordinarily difficult task because there's many 224 00:13:31,640 --> 00:13:35,720 different aspects of cognition that have to be involved. 225 00:13:35,720 --> 00:13:42,200 He has to first pay attention, then he has to remember what he's done. 226 00:13:42,200 --> 00:13:45,480 What I can't remember is how many I bought and how many I sold. 227 00:13:45,480 --> 00:13:47,880 And then he has to make decisions, 228 00:13:47,880 --> 00:13:49,920 what we call executive processing, 229 00:13:49,920 --> 00:13:52,400 he has to decide whether to buy or sell. 230 00:13:52,400 --> 00:13:55,800 So he's got multiple things that are going on at the same time. 231 00:13:57,160 --> 00:13:59,040 Oh, no, I bought loads of them. 232 00:14:01,440 --> 00:14:03,960 See, now I've got negative money, 233 00:14:03,960 --> 00:14:06,600 and no way of getting back out of the hole. 234 00:14:10,240 --> 00:14:13,520 My problem is that being on a high fat diet could limit 235 00:14:13,520 --> 00:14:14,520 the fuel for my brain. 236 00:14:16,560 --> 00:14:18,800 I'm really stuck on this now. 237 00:14:23,920 --> 00:14:26,040 Glucose is the primary fuel of the brain 238 00:14:26,040 --> 00:14:27,720 and the best fuel for the brain. 239 00:14:27,720 --> 00:14:30,120 Since he's been on a low carbohydrate diet, 240 00:14:30,120 --> 00:14:32,200 almost eating no carbohydrates, 241 00:14:32,200 --> 00:14:35,440 his stores of glucose in the body are going to be very low. 242 00:14:36,680 --> 00:14:39,720 Um, and therefore I think as time goes on, he may be having 243 00:14:39,720 --> 00:14:42,240 more difficulty with the task. 244 00:14:44,800 --> 00:14:48,560 And I'm short of glucose on my extreme high fat diet. 245 00:14:49,680 --> 00:14:52,000 But the body has a back-up plan. 246 00:14:52,000 --> 00:14:56,560 It can turn fat into energy compounds called ketones, 247 00:14:56,560 --> 00:14:58,200 but they aren't as efficient. 248 00:14:59,800 --> 00:15:03,520 In normal everyday life, that's not a problem. 249 00:15:03,520 --> 00:15:06,320 But when you need to think really hard, it can be. 250 00:15:07,600 --> 00:15:11,000 I've got the initials in head and I can't remember what they stand for. 251 00:15:11,000 --> 00:15:13,800 Then I've got to try and remember something about the companies. 252 00:15:15,040 --> 00:15:19,320 The professor's research indicates that without enough carbohydrate 253 00:15:19,320 --> 00:15:23,320 in your diet, your memory can be significantly compromised. 254 00:15:23,320 --> 00:15:28,920 There are certain parts of the brain that use carbohydrates, particularly for memory, 255 00:15:28,920 --> 00:15:33,760 and if they're aren't getting enough glucose, then they can not function properly. 256 00:15:36,160 --> 00:15:39,040 Getting Exile at 97 dollars 29. 257 00:15:40,880 --> 00:15:43,480 Over in London, things are markedly different. 258 00:15:44,840 --> 00:15:49,160 Chris on his high sugar diet is more alert, has more energy, 259 00:15:49,160 --> 00:15:51,400 and has a significantly better memory. 260 00:15:52,840 --> 00:15:57,640 When I'm thinking hard I can really feel inside my head 261 00:15:57,640 --> 00:15:59,960 brainwork going on, and this is very brain-heavy, 262 00:15:59,960 --> 00:16:02,920 it's remembering loads of numbers, remembering loads of initials, 263 00:16:02,920 --> 00:16:05,680 and learning a whole new language of bidding and asking. 264 00:16:05,680 --> 00:16:07,680 So this screen means everything's going green 265 00:16:07,680 --> 00:16:11,320 so everything's going up, so you just have to hope that continues. 266 00:16:13,360 --> 00:16:16,440 I think I might be doing OK on my high sugar diet, 267 00:16:16,440 --> 00:16:20,680 because the brain consumes 60% of the sugars in your blood. 268 00:16:20,680 --> 00:16:24,720 For people who are on diets that have complex carbohydrates, 269 00:16:24,720 --> 00:16:27,360 er, whole grains, fruits and vegetables, 270 00:16:27,360 --> 00:16:30,440 there's a lot of studies that show at least on a short-term basis 271 00:16:30,440 --> 00:16:35,320 that having a high carbohydrate diet will facilitate memory. 272 00:16:35,320 --> 00:16:36,320 It's such fun. 273 00:16:37,680 --> 00:16:40,160 I can see why these guys get really into it. 274 00:16:41,520 --> 00:16:44,840 It's the end of the test, so who won? 275 00:16:44,840 --> 00:16:46,880 I can't remember what I wanted to do, 276 00:16:46,880 --> 00:16:50,320 let alone the numbers and letters I needed to do it. 277 00:16:50,320 --> 00:16:51,520 I'm not cut out for this. 278 00:16:51,520 --> 00:16:54,400 Maybe Chris'll have done better. 279 00:16:54,400 --> 00:16:57,640 So Xand made...Xand made essentially 300 dollars profit 280 00:16:57,640 --> 00:17:00,680 and I've made over 800 dollars profit. 281 00:17:00,680 --> 00:17:02,320 So I absolutely thrashed him, 282 00:17:02,320 --> 00:17:05,080 and I tell you what, I could not have done that if I'd been 283 00:17:05,080 --> 00:17:09,080 feeling hungry or wanting something I couldn't have, like some sugar, 284 00:17:09,080 --> 00:17:12,360 and a big carb breakfast is what meant I could do that. 285 00:17:16,120 --> 00:17:19,600 Scientists are now beginning to understand how certain parts 286 00:17:19,600 --> 00:17:22,440 of our memory are affected by carbohydrates. 287 00:17:25,080 --> 00:17:29,000 On my high sugar diet I'm eating all kinds of carbs from starches 288 00:17:29,000 --> 00:17:30,960 to grains, vegetables to fruit. 289 00:17:36,200 --> 00:17:39,160 But no matter what form the carbohydrates come in, 290 00:17:39,160 --> 00:17:41,080 it's all broken down in my gut 291 00:17:41,080 --> 00:17:44,640 into single sugar molecules, like fructose or glucose. 292 00:17:51,080 --> 00:17:53,880 And the effect of these molecules on our bodies 293 00:17:53,880 --> 00:17:56,360 that's at the core of why some scientists, 294 00:17:56,360 --> 00:17:59,560 particularly in America, argue that sugar's bad for you. 295 00:18:03,680 --> 00:18:06,040 So Xand's in San Francisco, 296 00:18:06,040 --> 00:18:09,320 to meet one of the researchers who's led the charge against sugar. 297 00:18:16,680 --> 00:18:20,920 He's seeing Dr Robert Lustig, who's convinced that the way fructose 298 00:18:20,920 --> 00:18:25,240 and glucose work in our bodies leads to all kinds of health problems. 299 00:18:25,240 --> 00:18:28,120 Robert, do you want to pause in the doughnut store 300 00:18:28,120 --> 00:18:31,880 and get a bucket full? I...I... We'll talk about it later. 301 00:18:38,760 --> 00:18:42,640 For him, glucose and fructose are dangerous for different reasons. 302 00:18:43,680 --> 00:18:46,120 First of all, fructose. 303 00:18:46,120 --> 00:18:50,000 Turns out, only the liver can metabolise fructose, 304 00:18:50,000 --> 00:18:54,840 and you have a limit to how much you can metabolise, just like any drug. 305 00:18:54,840 --> 00:18:57,360 You have a threshold. 306 00:18:57,360 --> 00:19:01,120 If you go over that threshold, your liver has no choice 307 00:19:01,120 --> 00:19:04,800 but to take that extra energy that's been delivered to it 308 00:19:04,800 --> 00:19:06,160 and turn it into liver fat, 309 00:19:06,160 --> 00:19:09,240 because that's the way the way the liver gets rid of extra energy. 310 00:19:09,240 --> 00:19:12,120 So you drink a bottle of soda, some of it you can metabolise, 311 00:19:12,120 --> 00:19:14,120 but the rest of it has to become liver fat? 312 00:19:14,120 --> 00:19:15,040 That's right. 313 00:19:19,400 --> 00:19:23,680 And that liver fat can have damaging consequences for your health. 314 00:19:23,680 --> 00:19:27,760 It can make you more liable to heart disease, strokes, or diabetes. 315 00:19:29,160 --> 00:19:33,000 But according to Dr Lustig, that's just half the problem with sugar. 316 00:19:35,560 --> 00:19:37,960 The glucose molecule activates insulin, 317 00:19:37,960 --> 00:19:40,520 the hormone that controls blood sugar. 318 00:19:40,520 --> 00:19:44,000 But Lustig believes insulin does a whole lot more. 319 00:19:45,360 --> 00:19:50,080 Insulin shunts sugar to fat. The more insulin, the more fat. 320 00:19:50,080 --> 00:19:53,760 Well, guess what? The more insulin, the more disease, too. 321 00:19:53,760 --> 00:19:58,160 OK. And insulin is really the lynchpin in this whole story, 322 00:19:58,160 --> 00:20:01,680 because whether you gain weight and whether you get sick 323 00:20:01,680 --> 00:20:04,320 has everything to do with what your insulin does, 324 00:20:04,320 --> 00:20:07,200 and if you can keep your insulin level down, 325 00:20:07,200 --> 00:20:09,200 then you won't drive energy into fat, 326 00:20:09,200 --> 00:20:11,320 you have a chance to lose weight, 327 00:20:11,320 --> 00:20:13,240 you won't be making your arteries thicker, 328 00:20:13,240 --> 00:20:15,880 you have a chance for your blood pressure to come down, 329 00:20:15,880 --> 00:20:17,360 and this is what we've seen, 330 00:20:17,360 --> 00:20:19,320 is, "it's the insulin, stupid." 331 00:20:20,360 --> 00:20:23,800 It's known as the hormone hypothesis, 332 00:20:23,800 --> 00:20:27,680 because fat cells respond to the release of insulin by holding 333 00:20:27,680 --> 00:20:30,120 onto fat, and making more of it. 334 00:20:39,280 --> 00:20:42,520 In general, the studies that support the theory about fructose 335 00:20:42,520 --> 00:20:46,640 only looked at diets with unrealistically high levels of fructose. 336 00:20:47,800 --> 00:20:50,480 Much more than the average person consumes. 337 00:20:51,760 --> 00:20:54,640 So I'm not yet convinced about fructose. 338 00:20:56,200 --> 00:20:58,360 And as for the insulin hypothesis, 339 00:20:58,360 --> 00:21:01,600 the comprehensive study hasn't been done yet. 340 00:21:01,600 --> 00:21:04,440 So like most scientists in Britain, 341 00:21:04,440 --> 00:21:06,800 I'm pretty sceptical about these claims. 342 00:21:11,240 --> 00:21:13,960 I'm three weeks into my high fat diet 343 00:21:13,960 --> 00:21:16,600 and I'm really starting to miss carbohydrates. 344 00:21:17,840 --> 00:21:21,720 I've got on the plane very early, 345 00:21:21,720 --> 00:21:24,040 which means I can try and eat my burger quickly 346 00:21:24,040 --> 00:21:25,840 before anyone sits next to me. 347 00:21:25,840 --> 00:21:28,080 It's really hard not to eat the French fries. 348 00:21:33,160 --> 00:21:35,160 So I'm all done. 349 00:21:35,160 --> 00:21:36,960 This is what remains. 350 00:21:44,040 --> 00:21:46,080 But even though I couldn't eat the carbs, 351 00:21:46,080 --> 00:21:48,080 I wasn't ravenous after my meal. 352 00:21:49,320 --> 00:21:51,400 What I really want to know is 353 00:21:51,400 --> 00:21:54,800 if that has anything to do with the amount of fat in my diet? 354 00:22:03,600 --> 00:22:05,960 To try and understand what's happening, 355 00:22:05,960 --> 00:22:07,800 Xand has to fly back to Britain... 356 00:22:09,040 --> 00:22:12,560 Right, boys. We want you to do something... 357 00:22:12,560 --> 00:22:15,160 ..where Amanda Ursell has set up what she calls 358 00:22:15,160 --> 00:22:17,360 a hunger experiment. 359 00:22:23,920 --> 00:22:27,480 We start the day eating the same amount of calories for breakfast. 360 00:22:33,880 --> 00:22:37,680 Xand has a plateful of fat calories, but mine is chock full of sugar. 361 00:22:40,520 --> 00:22:44,360 Three hours later, we're offered lunch. 362 00:22:46,760 --> 00:22:49,440 And this is where it gets really interesting. 363 00:22:50,880 --> 00:22:55,360 Because now, Amanda can test whether or not eating fat or sugar 364 00:22:55,360 --> 00:22:59,480 has had any effect on how hungry we were. 365 00:22:59,480 --> 00:23:01,560 Well, I'm jotting down what you're having, 366 00:23:01,560 --> 00:23:03,880 so I'm going to count all the calories that you're going 367 00:23:03,880 --> 00:23:07,000 to have, so I know exactly what's on the plate, so, there we are. 368 00:23:07,000 --> 00:23:10,800 So will we eat the same number of calories like we did at breakfast? 369 00:23:10,800 --> 00:23:14,040 I'm going to start with this soup. OK, the soup. 370 00:23:14,040 --> 00:23:18,360 Come on, come on. Go on, then - off you go. 371 00:23:18,360 --> 00:23:22,560 Start eating. I'm going to work all this out for you. 372 00:23:22,560 --> 00:23:27,040 We both start hungry, but that doesn't last for long. 373 00:23:31,280 --> 00:23:33,520 Do you think I'm going to be able to eat all that? 374 00:23:33,520 --> 00:23:37,320 No, no. Delicious though this all looks, I'm not really enjoying it. 375 00:23:39,120 --> 00:23:41,000 All right, what else can I have? 376 00:23:41,000 --> 00:23:42,280 We've got some pasta. 377 00:23:42,280 --> 00:23:44,320 Pasta. Yeah. 378 00:23:44,320 --> 00:23:48,360 But is how hungry we feel just down to the calories we consume? 379 00:23:52,640 --> 00:23:55,040 It's like I just don't want any more of that. 380 00:23:55,040 --> 00:23:57,960 My brain has just said, "No, that's it, that's all you need." 381 00:23:57,960 --> 00:24:01,640 Can I take that? I need to measure what you've left. Absolutely. 382 00:24:03,000 --> 00:24:07,080 Or could it be the macronutrients in the meals, fat or sugar, 383 00:24:07,080 --> 00:24:09,160 that are governing how hungry we feel? 384 00:24:10,920 --> 00:24:14,520 On this diet I can still eat to shame. Really? 385 00:24:14,520 --> 00:24:18,600 To the moment at which I hate myself more than I want to keep eating. 386 00:24:20,880 --> 00:24:23,880 Can you get that whole meringue in your mouth at once? 387 00:24:30,600 --> 00:24:31,720 So we've got the results now. 388 00:24:34,040 --> 00:24:36,960 Later, Amanda gets busy with her calculator 389 00:24:36,960 --> 00:24:39,320 and tots up the final calorie count. 390 00:24:39,320 --> 00:24:42,800 OK, Xand, you're on the high fat diet, you had 825 calories. 391 00:24:42,800 --> 00:24:45,240 That's quite a lot. Yes, that's a big meal. 392 00:24:45,240 --> 00:24:49,720 Yeah, but you, Chris, on your carb blowout, you had, er 1,250 calories. 393 00:24:49,720 --> 00:24:52,960 Whoa! That's...that's half your calories for the day right there. 394 00:24:52,960 --> 00:24:55,680 That's half my whole day's calories in a single sitting. Yeah. 395 00:24:55,680 --> 00:24:59,800 For me, the interesting thing is, I ate more food than you, 396 00:24:59,800 --> 00:25:02,560 so calories do not necessarily make you feel full, 397 00:25:02,560 --> 00:25:05,560 and I was then hungrier quicker, 398 00:25:05,560 --> 00:25:07,640 so this really simple idea 399 00:25:07,640 --> 00:25:09,720 that we kind of learn that if you feel hungry 400 00:25:09,720 --> 00:25:12,240 you eat a meal and then you stop feeling hungry, 401 00:25:12,240 --> 00:25:14,080 even that is not really true. 402 00:25:14,080 --> 00:25:17,280 You can eat an enormous meal and end up being hungrier than the person 403 00:25:17,280 --> 00:25:20,160 who ate...you know, you ate almost the number of calories I did. 404 00:25:20,160 --> 00:25:22,000 What's going on there, then? Why is that? 405 00:25:22,000 --> 00:25:24,440 There's quite a big body of research that suggests that 406 00:25:24,440 --> 00:25:26,320 high protein diets make you feel fuller. 407 00:25:26,320 --> 00:25:28,320 It's the protein that's making me feel full? 408 00:25:28,320 --> 00:25:30,560 You don't really eat high fat on its own, 409 00:25:30,560 --> 00:25:33,080 you don't eat butter on its own or glug down olive oil on its own. 410 00:25:33,080 --> 00:25:34,200 Xand might. 411 00:25:34,200 --> 00:25:37,640 It comes with protein and makes you feel fuller than the carbohydrates. 412 00:25:37,640 --> 00:25:39,440 That's probably number 1. 413 00:25:42,120 --> 00:25:44,040 But it's more than that. 414 00:25:44,040 --> 00:25:47,160 Protein and sugar have very different effects on ghrelin - 415 00:25:47,160 --> 00:25:49,240 the hunger hormone. 416 00:25:49,240 --> 00:25:54,080 The more ghrelin you have in your body, the hungrier you'll feel. 417 00:25:55,440 --> 00:25:59,200 Protein suppresses ghrelin for longer than sugar. 418 00:26:02,240 --> 00:26:06,280 The problem with sugar is that it's an easy source of calories, 419 00:26:06,280 --> 00:26:08,080 and that can make you fat. 420 00:26:09,520 --> 00:26:13,600 But you can end up eating fewer calories on a high fat diet 421 00:26:13,600 --> 00:26:16,240 because of the interaction with ghrelin. 422 00:26:18,480 --> 00:26:20,120 Not all fats are the same, 423 00:26:20,120 --> 00:26:22,920 and fortunately on my diet I'm mostly on the good stuff. 424 00:26:22,920 --> 00:26:26,520 I'm eating lots of monosaturated and polyunsaturated fats, 425 00:26:26,520 --> 00:26:30,960 the kind of thing you find in eggs, olive oil, and oily fish. 426 00:26:30,960 --> 00:26:33,040 And that's all good for you. 427 00:26:33,040 --> 00:26:35,560 Now, I'm also eating quite a lot of saturated fat, 428 00:26:35,560 --> 00:26:39,120 which is the kind of thing you find in foods like meat and cheese. 429 00:26:39,120 --> 00:26:41,640 Now this stuff you're not recommended to have more 430 00:26:41,640 --> 00:26:44,040 than 30 grams a day because it raises your LDL, 431 00:26:44,040 --> 00:26:47,200 your bad cholesterol, but recently an increasing 432 00:26:47,200 --> 00:26:50,600 number of scientists are saying this may not actually be true. 433 00:26:50,600 --> 00:26:53,440 But there is no debate about trans fats. 434 00:26:53,440 --> 00:26:56,440 Now, trans fats are found in a wide range of manufactured foods 435 00:26:56,440 --> 00:27:00,320 like cakes and cookies, things like this, and they're not good for you. 436 00:27:00,320 --> 00:27:02,880 And what they do is they not only raise your LDL, 437 00:27:02,880 --> 00:27:07,440 your bad cholesterol, but they lower your HDL, your good cholesterol. 438 00:27:07,440 --> 00:27:10,760 Fortunately, on my diet I'm not allowed to have any of them. 439 00:27:18,600 --> 00:27:23,440 A gram of fat also has over twice as many calories as a gram of sugar. 440 00:27:26,120 --> 00:27:30,560 And our bodies turn dietary fats into body fat more easily 441 00:27:30,560 --> 00:27:32,000 than it does with sugar. 442 00:27:33,960 --> 00:27:37,280 Ultimately, of course, fat and sugar are sources of energy. 443 00:27:38,360 --> 00:27:44,000 So what we really want to know is how they work to fuel our bodies. 444 00:27:44,000 --> 00:27:46,640 It's now going to get personal and painful. 445 00:27:48,360 --> 00:27:52,520 What we're going to do is we'll have five minutes steady peddling away, 446 00:27:52,520 --> 00:27:55,520 I'm going to talk to you, I want to keep a nice conversation going, 447 00:27:55,520 --> 00:27:58,640 and then we're just going to start ramping it up a little bit. 448 00:27:58,640 --> 00:28:01,480 We set up another test, this time on a bike. 449 00:28:02,680 --> 00:28:05,480 This is very fun, I haven't used one of these before. 450 00:28:05,480 --> 00:28:07,760 Have you not? Oh, you're going to hate it soon. 451 00:28:07,760 --> 00:28:09,640 We've recruited Nigel Mitchell 452 00:28:09,640 --> 00:28:13,240 from the first ever British Tour de France winning cycling team 453 00:28:13,240 --> 00:28:14,240 to help us. 454 00:28:14,240 --> 00:28:17,280 Perfect, perfect, perfect. Just nice. Keeping up so far. 455 00:28:20,560 --> 00:28:23,800 This is the first exercise of any kind we've done in our diet, 456 00:28:23,800 --> 00:28:26,440 and we've not eaten for 12 hours. 457 00:28:26,440 --> 00:28:29,800 Your cadence looks nice. Drop a gear. 458 00:28:32,680 --> 00:28:35,480 We're 15 minutes into an hour-long session. 459 00:28:35,480 --> 00:28:38,000 Nigel wants to completely exhaust us. 460 00:28:39,280 --> 00:28:43,520 Ramp this up a little bit to 18mph now. Drop a gear? Drop a gear. 461 00:28:45,000 --> 00:28:47,440 Yeah, we're starting to work a bit more now. 462 00:28:49,600 --> 00:28:52,800 It's the first step in a particularly sadistic experiment, 463 00:28:52,800 --> 00:28:56,720 to see if fat or sugar is the best macronutrient for exercise. 464 00:29:01,280 --> 00:29:04,600 So, how much difference does the kind of nutrition science 465 00:29:04,600 --> 00:29:06,240 you're doing make to a team? 466 00:29:06,240 --> 00:29:08,280 I want to use foods to fuel them, 467 00:29:08,280 --> 00:29:10,520 I want to use foods for them to recover. 468 00:29:10,520 --> 00:29:12,560 So the foods that we give the guys 469 00:29:12,560 --> 00:29:15,600 is a mixture of bars and gels and protein. 470 00:29:15,600 --> 00:29:17,640 Breakfast, we use a lot of porridge. 471 00:29:17,640 --> 00:29:19,640 Now you can't get porridge on the continent, 472 00:29:19,640 --> 00:29:22,480 so for the Tour de France and all this we actually buy 473 00:29:22,480 --> 00:29:25,840 the porridge oats in this country and we take them out there. 474 00:29:25,840 --> 00:29:28,800 And last year it were about three weeks before the tour 475 00:29:28,800 --> 00:29:30,480 and I go around my local supermarket 476 00:29:30,480 --> 00:29:32,920 and I've got all my Sky kit on cos I'm working, and I've 477 00:29:32,920 --> 00:29:36,720 got a trolley full of porridge oats, I've got about 80kg of trolley oats. 478 00:29:36,720 --> 00:29:38,960 I put them on the conveyor belt and we take them through, 479 00:29:38,960 --> 00:29:41,440 and the woman on the conveyor belt, 480 00:29:41,440 --> 00:29:43,840 woman on the till just brings you down to Earth, she says, 481 00:29:43,840 --> 00:29:46,680 said to me, "So do you work in a care home or something, you know, 482 00:29:46,680 --> 00:29:48,840 "all this porridge oats that you've got?" 483 00:29:53,760 --> 00:29:56,920 45 minutes in, Nigel takes a blood sample. 484 00:29:59,080 --> 00:30:03,280 'The blood test confirm just how bad we feel. 485 00:30:03,280 --> 00:30:07,000 'Chris is burning sugar like crazy and his blood sugar levels 486 00:30:07,000 --> 00:30:11,600 'plummet from 4.7, where they were at the start of the test, to 2.7. 487 00:30:13,880 --> 00:30:18,480 'I'm faring better. My blood sugar has fallen by only about 25%.' 488 00:30:22,440 --> 00:30:25,960 This is doing exactly what we wanted it to do. 489 00:30:29,960 --> 00:30:34,360 Last minute, then, boys. Just keep it like this. 490 00:30:34,360 --> 00:30:38,040 'An hour of punishing exercise without food has pushed us to the 491 00:30:38,040 --> 00:30:39,880 'edge of our physical capabilities.' 492 00:30:42,720 --> 00:30:44,640 Yeah, I feel like I'm out of juice. 493 00:30:48,960 --> 00:30:52,040 'We're now both exhausted and empty, 494 00:30:52,040 --> 00:30:56,560 'which allows Nigel to test how fat and sugar fuel the body.' 495 00:30:56,560 --> 00:31:00,720 OK, boys, so we've done the hour on the turbo trainers at the top, 496 00:31:00,720 --> 00:31:04,720 we've pushed your blood sugars down, so you're just mild hypo... 497 00:31:04,720 --> 00:31:08,440 Get off! What we're going to do now is race up the hill. 498 00:31:08,440 --> 00:31:12,680 Now, we've got some food, so for Xander, we've got butter, 499 00:31:12,680 --> 00:31:15,240 so it's one pack of butter, please. Just one. 500 00:31:15,240 --> 00:31:18,480 And then I want you to take one in your pocket for eating 501 00:31:18,480 --> 00:31:21,880 on the way up, and then we've got a gel for you. 502 00:31:21,880 --> 00:31:24,400 The same number of calories in the gel. Roughly. 503 00:31:24,400 --> 00:31:27,840 We've got the same number of calories in the gel as the butter. 504 00:31:27,840 --> 00:31:29,080 But the gel is sugar. 505 00:31:29,080 --> 00:31:32,520 'There's nothing special about either the butter or the gel. 506 00:31:32,520 --> 00:31:35,320 'They're basically fat and sugar.' 507 00:31:35,320 --> 00:31:38,280 So, right, I want you to ride at my pace. 508 00:31:38,280 --> 00:31:41,600 I want us to control this, as we're going up there. 509 00:31:41,600 --> 00:31:44,280 A little bit easier on the gears. That's it, perfect. 510 00:31:44,280 --> 00:31:45,680 You're in the same gear. 511 00:31:45,680 --> 00:31:48,720 'Now it's time for the race up the hill, between fat in red 512 00:31:48,720 --> 00:31:50,320 'and sugar in blue.' 513 00:31:50,320 --> 00:31:54,880 When we turn right, we're going to start just lifting it slightly. 514 00:31:54,880 --> 00:31:58,480 Are you OK? Yeah, I'm all right. Just push on a bit more, then. 515 00:31:59,680 --> 00:32:04,000 'We're climbing the iconic and steep Box Hill in Surrey.' 516 00:32:04,000 --> 00:32:06,640 'And in the next few seconds, 517 00:32:06,640 --> 00:32:10,960 'it's going to turn into a fat versus sugar race to the summit.' 518 00:32:10,960 --> 00:32:13,520 What's your heart rates now, boys? 177. 519 00:32:13,520 --> 00:32:15,600 154. 520 00:32:15,600 --> 00:32:18,400 Just keep next to each other, if you can. 521 00:32:18,400 --> 00:32:21,040 OK? Right, are you ready, both of you? Go! 522 00:32:24,800 --> 00:32:27,360 Keep it going. Keep it going. 523 00:32:31,160 --> 00:32:34,880 'In the race to the top, Chris soon speeds away from me.' 524 00:32:39,120 --> 00:32:41,120 He just keeps getting further away 525 00:32:41,120 --> 00:32:45,720 and I cannot make my legs go any faster. 526 00:32:45,720 --> 00:32:48,200 It's like I'm stuck in one gear. 527 00:32:53,720 --> 00:32:57,680 'With my heart rate pumping at 200 beats per minute, 528 00:32:57,680 --> 00:33:00,440 I just manage to get to the top.' 529 00:33:00,440 --> 00:33:03,440 Just looking at you two, you've got a big smile on your face. 530 00:33:03,440 --> 00:33:06,240 You won the King of the Mountains there, Chris. 531 00:33:06,240 --> 00:33:09,400 Xander, you bunked out. But this is the thing. 532 00:33:09,400 --> 00:33:11,480 This is what we're trying to show. 533 00:33:11,480 --> 00:33:14,760 When you're really trying to push it, your body needs the sugar. 534 00:33:14,760 --> 00:33:18,520 It needs the carbohydrates. I want to measure the sugars again. 535 00:33:21,400 --> 00:33:24,840 7.1, your blood sugar now. 7.1. 536 00:33:26,280 --> 00:33:29,480 'Chris's blood sugars are so high because the sugar gel 537 00:33:29,480 --> 00:33:32,760 'he consumed half an hour ago is still pulsing through his body. 538 00:33:35,320 --> 00:33:39,040 'And that gave him the fuel to power his muscles up the hill. 539 00:33:40,880 --> 00:33:44,560 'But what about my blood sugar levels?' 540 00:33:44,560 --> 00:33:46,920 5.1, now that's interesting. 541 00:33:46,920 --> 00:33:51,640 All we've given you to eat is fat and we can't convert fat into sugar. 542 00:33:51,640 --> 00:33:54,320 'Completely deprived of glucose, 543 00:33:54,320 --> 00:33:58,600 'our bodies have a dramatic way of making sugar. 544 00:33:58,600 --> 00:34:02,800 'Protein in the form of muscle converts into amino acids, 545 00:34:02,800 --> 00:34:04,840 'which are then turned into glucose 546 00:34:04,840 --> 00:34:08,680 'and that's pumped into the blood, raising blood sugar levels. 547 00:34:13,360 --> 00:34:17,120 'So there's no question you can power your body without sugar, 548 00:34:17,120 --> 00:34:19,680 'but there is a price to pay.' 549 00:34:19,680 --> 00:34:23,240 Your blood sugars going up has got to be coming from the protein. 550 00:34:23,240 --> 00:34:25,160 He's burning muscle to make sugar. 551 00:34:25,160 --> 00:34:29,240 He's burning muscle to make sugar now. I feel quite rubbish. 552 00:34:29,240 --> 00:34:32,480 This is the last state you'd want one of your athletes to be in. 553 00:34:32,480 --> 00:34:35,720 If we'd got one of our riders and they were in your state in the 554 00:34:35,720 --> 00:34:40,600 Tour de France then I'd be looking for a new job. 555 00:34:40,600 --> 00:34:44,120 So we had identical turbos, we've got identical bikes, we've got 556 00:34:44,120 --> 00:34:47,080 the same tyre pressure, so you're doing the same work... 557 00:34:47,080 --> 00:34:49,680 We've got effectively the same person. 558 00:34:49,680 --> 00:34:52,760 Effectively the same person genetically. 559 00:34:52,760 --> 00:34:56,240 The big difference is the diet that you've been following. 560 00:34:59,080 --> 00:35:02,120 What's amazing about that is I haven't eaten any carbohydrate 561 00:35:02,120 --> 00:35:06,600 in weeks and my body can still make enough sugar to get me up that hill. 562 00:35:06,600 --> 00:35:08,680 How have you done this? 563 00:35:08,680 --> 00:35:12,480 How have you turned your dreadful performance up that 564 00:35:12,480 --> 00:35:17,040 hill into a kind of victory for fat? I got here, didn't I? 565 00:35:17,040 --> 00:35:19,840 And... Yes, you did have normal carbohydrate, which is... 566 00:35:19,840 --> 00:35:23,840 It's a point for me because your body needs carbohydrates to exercise like that. 567 00:35:23,840 --> 00:35:27,360 And where are you getting the carbohydrate? From your muscles. 568 00:35:27,360 --> 00:35:31,960 So you do exercise like that all day, you'll actually lose muscle and keep your little belly cos you're 569 00:35:31,960 --> 00:35:35,000 not turning that into carbs, are you? All right. 570 00:35:35,000 --> 00:35:36,640 I'll beat you on the way down. 571 00:35:36,640 --> 00:35:40,400 Yeah cos you're still fat! HE CHUCKLES 572 00:35:52,760 --> 00:35:55,960 This meal, it should be so good... 573 00:35:55,960 --> 00:35:59,800 It's missing one essential ingredient. 574 00:36:01,240 --> 00:36:02,920 And that's fat. 575 00:36:02,920 --> 00:36:04,680 So it's totally joyless. 576 00:36:04,680 --> 00:36:06,320 It's just a rubbish end to my day. 577 00:36:12,440 --> 00:36:15,800 At last, the diets are over. 578 00:36:15,800 --> 00:36:19,680 And we're back at the lab to find out what effect fat 579 00:36:19,680 --> 00:36:22,360 and sugar have had on our weight and health. 580 00:36:23,560 --> 00:36:27,840 OK, chaps. What I need you to do is get stripped off like before. 581 00:36:27,840 --> 00:36:32,120 'We're with our old friend Richard McKenzie to be weighed and measured.' 582 00:36:33,640 --> 00:36:36,040 OK, no talking, no moving. 583 00:36:36,040 --> 00:36:39,080 'Starting, of course, with the machine that measures 584 00:36:39,080 --> 00:36:42,040 'the percentage of fat and muscle in our bodies.' 585 00:36:43,280 --> 00:36:46,120 OK, and you're up next. 586 00:36:46,120 --> 00:36:50,200 '..Then close the door to begin tests.' 587 00:36:50,200 --> 00:36:55,280 'And he's got some good news and unfortunately, some bad news for us, 588 00:36:55,280 --> 00:36:59,960 'beginning with the results for the high sugar diet.' 589 00:36:59,960 --> 00:37:04,440 Chris, OK, you've lost 1kg of body mass. Is that good? 590 00:37:04,440 --> 00:37:09,680 You've been eating as much as you want of junk for a month 591 00:37:09,680 --> 00:37:11,320 and you've lost a kilo. 592 00:37:11,320 --> 00:37:13,760 Yeah, it's not bad. 593 00:37:13,760 --> 00:37:15,760 Half of that has come from body fat 594 00:37:15,760 --> 00:37:18,080 and the other half has come from muscle mass. 595 00:37:18,080 --> 00:37:22,960 Oh, really? So I have lost muscle as well? Yes. What about him? 596 00:37:22,960 --> 00:37:25,520 I feel like I've lost weight. You have. 597 00:37:25,520 --> 00:37:29,120 You've lost around 4kg of body mass. 598 00:37:29,120 --> 00:37:32,680 'On the high fat diet, Xand has lost more weight. 599 00:37:32,680 --> 00:37:36,320 'To be more accurate, 3.5 kilos in a month.' 600 00:37:36,320 --> 00:37:38,680 So, where has that weight loss come from? 601 00:37:38,680 --> 00:37:42,640 2kg has come from muscle mass, 1.5 has come from fat mass. 602 00:37:42,640 --> 00:37:44,640 I've lost weight, which is great, 603 00:37:44,640 --> 00:37:47,680 and I've lost a legitimate 1.5 kilos of fat. 604 00:37:47,680 --> 00:37:50,120 In four weeks, that's really good. 605 00:37:50,120 --> 00:37:52,360 On the face of it, that's very good. 606 00:37:52,360 --> 00:37:54,560 Yeah, on the face of it, 607 00:37:54,560 --> 00:37:58,480 but you've lost 1.5 kilos of fat and you've lost 2 kilos of muscle. 608 00:37:58,480 --> 00:38:01,720 Your brother's right. We have to look at it in a bit more detail 609 00:38:01,720 --> 00:38:05,560 and losing body weight is an ideal goal in some circumstances, 610 00:38:05,560 --> 00:38:09,000 but you've lost 2kg of muscle mass and that isn't healthy. 611 00:38:09,000 --> 00:38:11,840 Why is it so bad to have lost these 2 kilos of muscle? 612 00:38:11,840 --> 00:38:15,040 If you lose muscle mass, with disease or ageing, 613 00:38:15,040 --> 00:38:17,840 you are more likely to visit the hospital more often 614 00:38:17,840 --> 00:38:19,960 and have a poor life expectancy. 615 00:38:19,960 --> 00:38:22,200 Really? Yes. That bad? Yes. 616 00:38:22,200 --> 00:38:25,360 That's a really important counterintuitive thing, 617 00:38:25,360 --> 00:38:28,640 I think, that we're going to lose weight, go on a diet, we don't 618 00:38:28,640 --> 00:38:32,440 think too much about exercise, and it can be really bad for you. 619 00:38:39,640 --> 00:38:43,640 'Nervously, we went through the same battery of tests as we did 620 00:38:43,640 --> 00:38:48,280 'a month ago. First, we checked our cholesterol.' 621 00:38:48,280 --> 00:38:51,640 'We thought that because Xand was eating so much fat on his diet, 622 00:38:51,640 --> 00:38:53,920 'his levels would be much higher. 623 00:38:53,920 --> 00:38:56,280 'What was amazing is that they were nearly exactly 624 00:38:56,280 --> 00:39:00,400 'the same as they were at the start of our diets. 625 00:39:00,400 --> 00:39:03,520 'In fact, there was little or no change for either of us.' 626 00:39:05,680 --> 00:39:07,320 One minute to finish. 627 00:39:10,560 --> 00:39:12,600 'Finally, we tested our insulin, 628 00:39:12,600 --> 00:39:16,440 'the hormone that regulates the level of sugar in your blood.' 629 00:39:16,440 --> 00:39:18,880 Urgh! 630 00:39:18,880 --> 00:39:23,720 'Naturally enough, on the high sugar diet, I went first.' 631 00:39:23,720 --> 00:39:27,800 Your body's ability to produce insulin improved. 632 00:39:27,800 --> 00:39:30,640 That is the opposite... Totally the opposite 633 00:39:30,640 --> 00:39:33,920 of I think what we would expect, most doctors would expect, 634 00:39:33,920 --> 00:39:37,120 what most people in the street would expect. 635 00:39:37,120 --> 00:39:40,440 Probably just got used to dealing with the sugar, 636 00:39:40,440 --> 00:39:44,200 the glucose intake and therefore, responding by producing insulin. 637 00:39:44,200 --> 00:39:47,320 A bit like if I'd been drinking a lot for the month, 638 00:39:47,320 --> 00:39:50,760 my liver would up-regulate the enzymes to deal with the alcohol. 639 00:39:50,760 --> 00:39:52,400 It's almost the same thing. 640 00:39:52,400 --> 00:39:55,520 Because I've been eating loads of sugar, 641 00:39:55,520 --> 00:39:59,760 I've become better at managing it. You're better at producing insulin. 642 00:39:59,760 --> 00:40:01,320 Is that good or not? 643 00:40:01,320 --> 00:40:03,040 Um... 644 00:40:03,040 --> 00:40:05,600 In the short term, it is good, but long term, 645 00:40:05,600 --> 00:40:08,360 it might produce a problem. 646 00:40:08,360 --> 00:40:11,720 'An unexpected result for me. 647 00:40:11,720 --> 00:40:16,200 'But what about Xand on the high fat diet?' 648 00:40:16,200 --> 00:40:18,800 What is worrying is your body is not responding to 649 00:40:18,800 --> 00:40:20,720 insulin as well as it did. 650 00:40:20,720 --> 00:40:25,320 If you eat too much fat, that can stop your body responding to 651 00:40:25,320 --> 00:40:29,240 insulin and it also can tell your body to produce more glucose. 652 00:40:29,240 --> 00:40:33,800 So how serious is this? It's only a month. Is this a big difference that you're seeing? 653 00:40:33,800 --> 00:40:35,840 Actually, it is a big difference. 654 00:40:35,840 --> 00:40:39,960 What we've seen is your blood glucose has climbed from 5.1, 655 00:40:39,960 --> 00:40:43,400 which it was before the diet, which wasn't great to start with, 656 00:40:43,400 --> 00:40:47,440 but still in a healthy range, to 5.9. 657 00:40:47,440 --> 00:40:51,480 You're only 0.2 away from being pre-diabetic. 658 00:40:51,480 --> 00:40:53,080 Wow! 659 00:40:53,080 --> 00:40:56,560 In a month, I've done myself some proper damage. 660 00:40:56,560 --> 00:40:59,440 This isn't good for me at all. It's not good for you. 661 00:40:59,440 --> 00:41:02,480 That's the first thing. You should stop that diet. 662 00:41:07,760 --> 00:41:10,280 Eventually, your body will stop producing insulin 663 00:41:10,280 --> 00:41:11,600 if you carry on down this path. 664 00:41:11,600 --> 00:41:13,920 I've been on a no-sugar diet 665 00:41:13,920 --> 00:41:16,920 and I just would have thought I'd be making less insulin 666 00:41:16,920 --> 00:41:20,360 and needing less insulin. You're saying I'm making more insulin, 667 00:41:20,360 --> 00:41:22,360 my body isn't reacting to it as well 668 00:41:22,360 --> 00:41:24,840 and I'm well down the road to diabetes, 669 00:41:24,840 --> 00:41:26,240 which is, which is bad news. 670 00:41:26,240 --> 00:41:28,680 It's bad news, you're heading that way. 671 00:41:35,600 --> 00:41:37,640 So I thought if you eat lots of sugar, 672 00:41:37,640 --> 00:41:39,840 you make lots of insulin and that's bad, 673 00:41:39,840 --> 00:41:43,240 but it turns out me eating lots of fat makes my body insulin-resistant 674 00:41:43,240 --> 00:41:45,960 so I make more insulin and that's worse. 675 00:41:45,960 --> 00:41:47,400 So I'm...I'm doing really... 676 00:41:47,400 --> 00:41:50,080 Like, I'm close to being diabetic now, I'm not...I'm not well! 677 00:41:50,080 --> 00:41:53,200 I mean, was wrong too. Like I...so I thought, "Well, I'm having coffee, 678 00:41:53,200 --> 00:41:55,680 "I can't have my cream in it, so I'll put in lots of sugar," 679 00:41:55,680 --> 00:41:58,160 so I ate so much more sugar that I normally would... 680 00:41:58,160 --> 00:42:02,400 And I'd have thought that would make you diabetic or close to it. That's...that's, I think we all, 681 00:42:02,400 --> 00:42:05,640 that's the received wisdom of becoming diabetic is about eating sugar. 682 00:42:05,640 --> 00:42:09,320 When are we ever going to learn that if you...it's never about one thing. 683 00:42:09,320 --> 00:42:11,920 We say, "Oh, it must be fat or it must be sugar..." 684 00:42:11,920 --> 00:42:14,800 No, it is ALWAYS more complicated than that. Always 685 00:42:14,800 --> 00:42:17,400 It's like a really basic rule in life, isn't it? If someone 686 00:42:17,400 --> 00:42:20,480 is selling you one simple solution to a problem that everyone has, 687 00:42:20,480 --> 00:42:22,520 it probably isn't going to work. No. 688 00:42:39,560 --> 00:42:42,440 As doctors, we know we have got to be careful 689 00:42:42,440 --> 00:42:47,240 about extrapolating too much from our own experience. 690 00:42:47,240 --> 00:42:50,320 Human physiology can be extremely complicated. 691 00:42:58,880 --> 00:43:02,520 Being on a low-fat or a low-carb diet yourself, you learn all kinds 692 00:43:02,520 --> 00:43:05,720 of things that you could never get from reading about it in a paper. 693 00:43:05,720 --> 00:43:08,440 You learn about the experience of being on it, 694 00:43:08,440 --> 00:43:12,200 whether or not it's fun, whether or not it's nasty, how it feels. 695 00:43:12,200 --> 00:43:14,920 But the numbers that you get from an experiment 696 00:43:14,920 --> 00:43:17,160 with just two people aren't definitive. 697 00:43:17,160 --> 00:43:19,600 They're interesting, but they don't tell you enough. 698 00:43:19,600 --> 00:43:22,640 To get definitive information from those numbers, 699 00:43:22,640 --> 00:43:24,680 you have to look at the experiments 700 00:43:24,680 --> 00:43:27,080 that are being done on thousands of people. 701 00:43:35,640 --> 00:43:37,080 Over the last few years, 702 00:43:37,080 --> 00:43:39,440 as the world's got fatter and more unhealthy, 703 00:43:39,440 --> 00:43:42,120 finding an answer to the fat-versus-sugar question 704 00:43:42,120 --> 00:43:44,040 has become even more pressing. 705 00:43:51,680 --> 00:43:55,160 One of Britain's leading nutritionists, Professor Susan Jebb, 706 00:43:55,160 --> 00:43:58,160 has been researching this for more than a decade. 707 00:43:58,160 --> 00:44:01,800 And she started with a simple observation. 708 00:44:01,800 --> 00:44:04,040 We've been looking at this for...for many years 709 00:44:04,040 --> 00:44:06,280 and I guess what I struggle with is the idea that, 710 00:44:06,280 --> 00:44:09,560 you know, people start off thin, or lean... 711 00:44:09,560 --> 00:44:12,640 Uh-huh. ..and at some point during their lives, 712 00:44:12,640 --> 00:44:15,240 many people end up gaining weight, becoming fat... 713 00:44:15,240 --> 00:44:16,440 This is me at the moment. 714 00:44:16,440 --> 00:44:19,640 And a proportion of those go on to become sick and they develop 715 00:44:19,640 --> 00:44:24,400 illnesses, like cardiovascular disease or...or diabetes. 716 00:44:26,280 --> 00:44:28,880 We're in no doubt about this link, that being fat makes 717 00:44:28,880 --> 00:44:31,760 a lot of people, not everyone, but a lot of people ill. 718 00:44:31,760 --> 00:44:34,120 Absolutely, increases your risk of heart disease, 719 00:44:34,120 --> 00:44:35,960 of cancer and of diabetes. 720 00:44:35,960 --> 00:44:39,520 OK. So is it something about their diet which alters that risk? 721 00:44:39,520 --> 00:44:46,520 We looked at um...at the amount of fat or carbs or indeed protein... 722 00:44:46,520 --> 00:44:50,800 'So she set up a series of long-running, comprehensive studies 723 00:44:50,800 --> 00:44:53,360 'to see what effects feeding people fat, 724 00:44:53,360 --> 00:44:56,760 'sugar and protein had on their health and well-being.' 725 00:44:56,760 --> 00:44:59,880 And more than that, we've tried to study the differences 726 00:44:59,880 --> 00:45:03,400 in these groups, so we've been interested in saturated fat... 727 00:45:03,400 --> 00:45:06,040 'She fed them bad fats - saturated fats, 728 00:45:06,040 --> 00:45:09,920 'and good fats - monounsaturated fats. 729 00:45:09,920 --> 00:45:12,120 'She did the same with carbohydrates, 730 00:45:12,120 --> 00:45:15,680 'feeding people low and high GI, whole grains and refined grains.' 731 00:45:18,200 --> 00:45:22,680 Maybe is about the fibre in the food or maybe is about sugar. 732 00:45:24,080 --> 00:45:26,080 'For ten years, 733 00:45:26,080 --> 00:45:29,640 'she conducted a series of detailed scientific studies 734 00:45:29,640 --> 00:45:33,120 'into which was worst - fat or sugar.' 735 00:45:33,120 --> 00:45:35,880 So I'm on tenterhooks, like, so what did you find? 736 00:45:35,880 --> 00:45:39,160 You know, the changes that we got were important, 737 00:45:39,160 --> 00:45:40,920 but they were quite modest. 738 00:45:40,920 --> 00:45:46,040 They were surprisingly small, much smaller than I was anticipating. 739 00:45:46,040 --> 00:45:48,760 And there are clear benefits 740 00:45:48,760 --> 00:45:51,360 of a little bit more monounsaturated fats, 741 00:45:51,360 --> 00:45:54,600 some benefits of low GI, some of more fibre, 742 00:45:54,600 --> 00:45:58,680 but I really don't think we could say that a diet 743 00:45:58,680 --> 00:46:05,360 which had some extreme composition was really a revolutionary answer. 744 00:46:08,520 --> 00:46:13,240 What her study showed was that changing fat or sugar on their own 745 00:46:13,240 --> 00:46:14,680 had a very small effect. 746 00:46:19,280 --> 00:46:24,040 Especially when compared to the effect of losing or gaining weight. 747 00:46:34,000 --> 00:46:35,640 So what is it that we're eating 748 00:46:35,640 --> 00:46:39,000 that's making us fatter and unhealthier? 749 00:46:39,000 --> 00:46:43,520 Unlikely as it may seem, the first clue in solving that puzzle 750 00:46:43,520 --> 00:46:46,080 might lie in this tempting tray of doughnuts. 751 00:46:51,200 --> 00:46:53,680 What I want you to do is look at this tray of doughnuts 752 00:46:53,680 --> 00:46:57,840 and think about which one you'd choose if you could have any of them. 753 00:46:57,840 --> 00:46:59,040 Got it? 754 00:46:59,040 --> 00:47:00,800 Now, this is like a card trick, 755 00:47:00,800 --> 00:47:04,000 I want you to remember the doughnut you chose and we're going to see 756 00:47:04,000 --> 00:47:07,320 if the people in New York choose the same one as you. 757 00:47:07,320 --> 00:47:09,920 All you have to do is choose a doughnut. 758 00:47:09,920 --> 00:47:11,120 Ah, it's easy. 759 00:47:18,480 --> 00:47:20,520 I'm going to find out if people in London 760 00:47:20,520 --> 00:47:23,800 have the same taste in doughnuts as people in New York. 761 00:47:23,800 --> 00:47:26,400 Right, do you want a free doughnut? 762 00:47:26,400 --> 00:47:28,200 Er...I would like this one. 763 00:47:28,200 --> 00:47:29,840 The same one. Yeah, yeah, yeah. 764 00:47:32,680 --> 00:47:34,920 So can I offer you a doughnut? 765 00:47:34,920 --> 00:47:37,320 Yeah, go for it, go for it, yes! 766 00:47:37,320 --> 00:47:38,480 I'm on a diet. 767 00:47:38,480 --> 00:47:39,880 XAND LAUGHS 768 00:47:41,200 --> 00:47:42,920 Is that good? Yeah, it's good. 769 00:47:44,760 --> 00:47:46,280 Everyone pick a doughnut. 770 00:47:47,480 --> 00:47:50,120 That's my favourite one. Is it? It's my favourite one as well. 771 00:47:52,280 --> 00:47:54,600 You said that was your favourite one, why? 772 00:47:55,840 --> 00:47:57,880 Just cos I've tried practically all of them 773 00:47:57,880 --> 00:47:59,720 and I just like this one. 774 00:47:59,720 --> 00:48:02,160 Guys, thank you very much. Thank you! Enjoy your day! 775 00:48:02,160 --> 00:48:05,000 So it's really interesting - all the glazed doughnuts have gone, 776 00:48:05,000 --> 00:48:07,040 only one person picked the chocolate one. 777 00:48:07,040 --> 00:48:10,480 Everyone seems to be going for the glazed ring. 778 00:48:10,480 --> 00:48:12,160 Let's see if that continues. 779 00:48:13,640 --> 00:48:19,400 'So why is that? What's so special about this particular doughnut? 780 00:48:24,600 --> 00:48:27,760 'The doughnut preferences of Londoners and New Yorkers 781 00:48:27,760 --> 00:48:31,360 'is in fact a clue to what we think is some of the most intriguing 782 00:48:31,360 --> 00:48:32,920 'new science in nutrition. 783 00:48:34,600 --> 00:48:38,160 'The real work is being done with rats and what they like eating. 784 00:48:40,960 --> 00:48:43,800 'Everyday rodents who work with Professor Paul Kenny, 785 00:48:43,800 --> 00:48:47,400 'a world-renowned researcher in the neurobiology of obesity 786 00:48:47,400 --> 00:48:50,680 'and, rather interestingly, addiction. 787 00:48:50,680 --> 00:48:53,960 'He devised a series of elegant experiments to work out 788 00:48:53,960 --> 00:48:55,840 'what foods we like and why. 789 00:48:58,000 --> 00:49:00,720 'The first thing he did was feed his rats sugar. 790 00:49:00,720 --> 00:49:02,880 'And they could have as much as they wanted.' 791 00:49:04,680 --> 00:49:07,760 The animals, of course, enjoy them and they'll consume vigorously, 792 00:49:07,760 --> 00:49:10,320 but they tend not to gain weight, because what they do is 793 00:49:10,320 --> 00:49:13,280 they adjust the consumption of other macronutrients to compensate. 794 00:49:13,280 --> 00:49:17,920 So, on average, animals with access to high-sugar solutions 795 00:49:17,920 --> 00:49:20,360 consumed the same amount of calories each day as they would 796 00:49:20,360 --> 00:49:22,760 if they weren't having access to those solutions. 797 00:49:22,760 --> 00:49:26,440 Really? So if you let a rat drink all the soda it wants to, 798 00:49:26,440 --> 00:49:30,480 or you let it have unlimited access to sugar, it doesn't get fat? 799 00:49:30,480 --> 00:49:32,280 Typically, no. 800 00:49:32,280 --> 00:49:36,040 'Then, he gave them as much fatty food as they wanted.' 801 00:49:36,040 --> 00:49:38,200 If you just give them access to fat, 802 00:49:38,200 --> 00:49:40,840 they will gain some weight, but really not that much, 803 00:49:40,840 --> 00:49:44,120 and what you find is they don't eat as much, physically eat as much 804 00:49:44,120 --> 00:49:46,520 food as they would've before, the reason being 805 00:49:46,520 --> 00:49:49,000 that they know that the fat is high in calories 806 00:49:49,000 --> 00:49:50,880 and their body is quick to deal with that. 807 00:49:50,880 --> 00:49:54,240 They have signals that tell them, "You've had enough, stop eating." 808 00:49:54,240 --> 00:49:56,880 'And there's something simple you can do at home to get 809 00:49:56,880 --> 00:49:59,520 'a sense of what Professor Kenny's been studying.' 810 00:50:02,680 --> 00:50:05,440 This is double cream and it's thick, 811 00:50:05,440 --> 00:50:08,280 it's luxurious, it's rich, 812 00:50:08,280 --> 00:50:09,720 it's creamy... 813 00:50:12,320 --> 00:50:14,880 ..and it's really boring. 814 00:50:14,880 --> 00:50:16,520 This is sugar. 815 00:50:23,920 --> 00:50:29,680 After even with one mouthful, it's overpowering. 816 00:50:31,120 --> 00:50:33,640 BUT if we mix them together... 817 00:50:42,160 --> 00:50:44,440 Now, that stuff I could eat all day, 818 00:50:44,440 --> 00:50:48,080 and in fact, we do eat this all the time, 819 00:50:48,080 --> 00:50:50,760 cos basically, what we've just made is ice cream. 820 00:50:53,040 --> 00:50:57,320 Now, this ice cream is absolutely delicious and the reason it tastes 821 00:50:57,320 --> 00:51:01,840 so good is because the combination of fat and sugar is unbelievable. 822 00:51:03,120 --> 00:51:04,320 Mm. 823 00:51:07,400 --> 00:51:10,480 So, Professor Kenny took this simple insight 824 00:51:10,480 --> 00:51:14,120 and fed his rats foods that were high in fat and sugar. 825 00:51:14,120 --> 00:51:17,760 So what happened when you fed cheesecake to rats? 826 00:51:17,760 --> 00:51:21,360 They practically stopped eating the regular, healthy food that 827 00:51:21,360 --> 00:51:24,240 was there, but they didn't binge on the high fat, high sugar stuff, 828 00:51:24,240 --> 00:51:27,080 they grazed on it, but that was their main source of calories. 829 00:51:27,080 --> 00:51:29,680 This is the going to the fridge and just having a spoonful 830 00:51:29,680 --> 00:51:31,920 of ice cream every 20 minutes. Precisely, yeah. 831 00:51:31,920 --> 00:51:34,200 You know, you get up and you eat, but if you're going to eat 832 00:51:34,200 --> 00:51:37,040 it's for that type of food and you tend to eat much more frequently. 833 00:51:37,040 --> 00:51:39,880 You're not gorging on it, but that's what you eat continuously. 834 00:51:39,880 --> 00:51:42,160 And those animals gained a massive amount of weight, 835 00:51:42,160 --> 00:51:45,040 they really gained a lot of weight, and they became sedentary. 836 00:51:45,040 --> 00:51:46,680 They slept a lot, didn't move around, 837 00:51:46,680 --> 00:51:48,920 but that was where they got their calories from. 838 00:51:51,920 --> 00:51:54,520 What Professor Kenny's discovered is that, 839 00:51:54,520 --> 00:51:56,680 unlike fat and sugar on their own, 840 00:51:56,680 --> 00:52:00,960 the rats had no off switch when it came to fat and sugar combined. 841 00:52:00,960 --> 00:52:04,280 The combination of fat and sugar is completely different 842 00:52:04,280 --> 00:52:07,640 than either macronutrient alone, and it tastes remarkably good. 843 00:52:11,160 --> 00:52:14,280 And so what you have are these systems in the brain that are there 844 00:52:14,280 --> 00:52:16,680 to respond to not whether you need food to live, 845 00:52:16,680 --> 00:52:19,080 but whether you like using food, 846 00:52:19,080 --> 00:52:22,320 and they're engaged, they're called hedonic systems. 847 00:52:24,760 --> 00:52:27,760 It's much like what happens with drug addiction. 848 00:52:27,760 --> 00:52:30,080 You don't need heroin, you don't need cocaine, 849 00:52:30,080 --> 00:52:32,720 it's got no nutrient value, it's got no caloric value, 850 00:52:32,720 --> 00:52:35,240 it doesn't do anything for you except make you feel good. 851 00:52:38,600 --> 00:52:42,000 And it's exactly those hedonic systems in the brain that we think 852 00:52:42,000 --> 00:52:45,680 are being impacted far more when you consume food 853 00:52:45,680 --> 00:52:49,240 that's rich in fat and sugar, than consuming either sugar or fat alone. 854 00:52:52,040 --> 00:52:55,880 When you think about it, we all know we need to eat to live. 855 00:52:59,280 --> 00:53:03,040 But what Professor Kenny's discovered is that the combination 856 00:53:03,040 --> 00:53:06,960 of fat and sugar supercharges the brain's reward system, 857 00:53:06,960 --> 00:53:10,800 overpowering its ability to tell us to stop eating. 858 00:53:13,720 --> 00:53:16,400 And it's a manufactured combination, 859 00:53:16,400 --> 00:53:18,720 you can't find it anywhere else in nature. 860 00:53:25,600 --> 00:53:27,960 But here's what's even more remarkable. 861 00:53:29,200 --> 00:53:31,720 He's discovered that his rats didn't just like 862 00:53:31,720 --> 00:53:33,480 a mixture of fat and sugar, 863 00:53:33,480 --> 00:53:38,760 the ratio of fat to sugar was crucial to how much they liked it. 864 00:53:40,560 --> 00:53:43,400 When I looked at the composition of cheesecake and I was surprised. 865 00:53:43,400 --> 00:53:47,560 It had a highest percentage of fat of any food item 866 00:53:47,560 --> 00:53:49,760 that we looked at that wasn't actually pure fat, 867 00:53:49,760 --> 00:53:52,000 and it had remarkably high levels of sugar. So it was 868 00:53:52,000 --> 00:53:55,360 the combination... What's the ratio of fat and sugar in cheesecake? 869 00:53:55,360 --> 00:53:57,200 It's pretty much 50/50. Really? 870 00:53:57,200 --> 00:53:59,520 It's about a half fat and the rest of it sugar 871 00:53:59,520 --> 00:54:02,360 with various other things to keep the whole product together. 872 00:54:02,360 --> 00:54:04,960 OK. So it's basically half fat and half sugar. 873 00:54:04,960 --> 00:54:06,760 Chaps, can I offer you doughnuts? 874 00:54:06,760 --> 00:54:08,560 OK, there you go, go for it. 875 00:54:08,560 --> 00:54:11,640 I like these ones. Tuck in, there's no trick. 876 00:54:13,280 --> 00:54:16,360 Now remember, the most popular doughnut was this one, 877 00:54:16,360 --> 00:54:18,560 the glazed ring, 878 00:54:18,560 --> 00:54:21,200 and there's something really special about this doughnut, 879 00:54:21,200 --> 00:54:25,200 it's got an exactly 50/50 mixture of fat and sugar. 880 00:54:25,200 --> 00:54:28,280 The pink one, that's got extra sugar on the top, 881 00:54:29,880 --> 00:54:32,040 and this one is filled with cream. 882 00:54:33,160 --> 00:54:34,600 So there's no question, 883 00:54:34,600 --> 00:54:38,040 we absolutely love this combination of fat and sugar. 884 00:54:40,840 --> 00:54:43,760 It's no surprise that people liked this doughnut. 885 00:54:43,760 --> 00:54:46,680 It tends to be the bestseller on both sides of the Atlantic. 886 00:54:52,200 --> 00:54:55,680 The fact that the world is getting fatter is a new phenomenon, 887 00:54:55,680 --> 00:54:57,320 and what seems to be driving it, 888 00:54:57,320 --> 00:55:00,760 at least according to Professor Kenny, is processed food, 889 00:55:00,760 --> 00:55:03,840 because that's where you find this deadly combination 890 00:55:03,840 --> 00:55:07,080 of fat and sugar that you don't find anywhere else in nature. 891 00:55:07,080 --> 00:55:11,360 And what this does is it fundamentally interferes 892 00:55:11,360 --> 00:55:14,480 with our mechanisms of self-regulation and reward. 893 00:55:22,360 --> 00:55:25,320 It seems that it's fat and sugar together, 894 00:55:25,320 --> 00:55:28,640 not fat or sugar alone, that's the real problem. 895 00:55:30,680 --> 00:55:35,320 And Chris wanted to find out from Professor Jebb what we could do about it. 896 00:55:36,600 --> 00:55:39,000 When people tell me they crave sugar, 897 00:55:39,000 --> 00:55:41,200 I say, "What, sugar out of the sugar bowl? 898 00:55:41,200 --> 00:55:44,880 "Oh, no, no, no." Or fat, pats of butter? Generally not. 899 00:55:44,880 --> 00:55:48,560 What people really seem to desire, whether that's physiological 900 00:55:48,560 --> 00:55:53,000 or whether it's a learnt behaviour is these fat/sugar combinations. 901 00:55:53,000 --> 00:55:56,440 They are very energy dense, so they pack the calories in, 902 00:55:56,440 --> 00:55:59,880 and they are unbelievably pleasurable and attractive. 903 00:55:59,880 --> 00:56:01,880 Are these temptations for you as well? 904 00:56:01,880 --> 00:56:03,960 Oh, I think they're temptations for most of us. 905 00:56:03,960 --> 00:56:06,040 One of the things that I often say 906 00:56:06,040 --> 00:56:09,160 is it's astonishing that any of us stay slim. 907 00:56:09,160 --> 00:56:12,800 In a world like this where in Britain we are surrounded 908 00:56:12,800 --> 00:56:18,560 by pretty delicious, relatively affordable, palatable foods, 909 00:56:18,560 --> 00:56:23,000 actually you have to exert quite a level of dietary restraint 910 00:56:23,000 --> 00:56:26,120 if you're not going to effectively just sleep-walk into obesity. 911 00:56:26,120 --> 00:56:28,200 So I want your top tip, 912 00:56:28,200 --> 00:56:32,600 a basic rule, like my go to thing when I'm feeling weak. 913 00:56:32,600 --> 00:56:37,120 By making some pretty modest changes, but right across your diet. 914 00:56:37,120 --> 00:56:40,960 Certainly cutting out some of those kind of discretionary 915 00:56:40,960 --> 00:56:44,360 treat type foods which are no longer really treats, 916 00:56:44,360 --> 00:56:46,080 they've become everyday items. Yes. 917 00:56:46,080 --> 00:56:48,880 If you take those out you can cut calories 918 00:56:48,880 --> 00:56:52,280 and you can cut lots of those other nutrients of concern. 919 00:56:52,280 --> 00:56:54,920 So you end up with a healthier diet 920 00:56:54,920 --> 00:56:57,440 and one on which you can also lose some weight. 921 00:56:57,440 --> 00:57:00,040 And I think that really is the secret to developing 922 00:57:00,040 --> 00:57:03,640 a much more holistic attitude to food, 923 00:57:03,640 --> 00:57:08,560 which doesn't sort of believe that any one item is a saviour 924 00:57:08,560 --> 00:57:12,920 or a sinner, it is about the overall balance of the diet. 925 00:57:20,120 --> 00:57:21,960 We've all heard that before 926 00:57:21,960 --> 00:57:25,200 but the difference is that we now know our enemy. 927 00:57:27,440 --> 00:57:28,880 It's not fat. 928 00:57:30,680 --> 00:57:32,120 And it's not sugar. 929 00:57:33,520 --> 00:57:35,600 But the deadly, addictive, 930 00:57:35,600 --> 00:57:39,520 delicious mixture of fat and sugar combined. 931 00:57:42,480 --> 00:57:45,080 What's amazing to me about all this is that 932 00:57:45,080 --> 00:57:47,280 I've been a doctor for ten years, 933 00:57:47,280 --> 00:57:49,000 I've spent six years at medical school, 934 00:57:49,000 --> 00:57:52,680 and I thought I knew a lot of this stuff and I just didn't, 935 00:57:52,680 --> 00:57:54,880 like I was wrong about a lot of stuff. 936 00:57:54,880 --> 00:57:57,000 So basically what I get out of this is 937 00:57:57,000 --> 00:58:00,600 I have to avoid the processed food, the doughnuts, the ice cream, 938 00:58:00,600 --> 00:58:04,600 the cheesecake, that sort of 50/50 fat/sugar mixture 939 00:58:04,600 --> 00:58:07,440 I cannot stop eating, and it's... and that's the problem. 940 00:58:07,440 --> 00:58:09,440 So I'm going to cut those out completely. 941 00:58:09,440 --> 00:58:12,920 So that where I end up is going all faddish diets, 942 00:58:12,920 --> 00:58:15,960 all faddish diets, are wrong and misguided, 943 00:58:15,960 --> 00:58:17,840 all of them. Yeah. 944 00:58:17,840 --> 00:58:20,040 And doing exercise is really important. 945 00:58:20,040 --> 00:58:22,800 You need to keep the muscle because muscle is an endocrine organ 946 00:58:22,800 --> 00:58:25,160 that affects your whole metabolism. 947 00:58:25,160 --> 00:58:28,000 So, in the end, as doctors, we'd love to be able to give 948 00:58:28,000 --> 00:58:30,960 one simple rule or give you a pill that would fix all this, 949 00:58:30,960 --> 00:58:32,880 but in the end we can't. 950 00:58:32,880 --> 00:58:35,000 It's up to you. It's up to YOU. 951 00:58:35,000 --> 00:58:37,400 All right, it's up to... It's up to you too.