The following is part of a
transcript from a BBC report examining the results of several scientific studies trying to determine HOW Atkins actually contributes to weight loss.
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NARRATOR: The Atkins camp disputes all these complications. With no long term studies focussed on the diet none can be proven. But beyond all that there was still one serious unanswered question. No one had yet systematically looked at how the Atkins diet actually worked. So late last year Horizon commissioned a scientific investigation in to whether Dr Atkins's theories of how calories are lost on his diet were real or just wishful thinking. The study took place at Kansas University. Somewhere on this sprawling campus a man was locked inside a tiny room. He was there for a whole day and night. His identical twin was subjected to the same treatment. They had both donated their bodies to one of the first attempts to find evidence that you really do lose more calories than normal on the Atkins diet. The team behind this unique study was headed by Joe Donnelly.
Prof JOSEPH DONNELLY: The concept is very interesting, it's very controversial, in science it's very nice to be there. It's nice to do something that isn't boring, there are millions of people interested in Atkins, really right, wrong or indifferent. So we're very interested and eager to see the results.
NARRATOR: For two weeks one of the twins was put on the high fat, high protein Atkins diet. While the other was put on the conventional low fat diet. They were then locked inside this sealed chamber. By measuring how much oxygen they breathed in and out the computers could calculate how quickly their bodies were burning fuel. The hope was that this would begin to answer whether more calories are worked off on the Atkins diet by breaking down fats and proteins. Donnelly also tested Dr Atkins's theory of calories lost as ketones down the toilet. The twins had to donate their bodily fluids for the duration of their internment.
Prof JOSEPH DONNELLY: We've collected a litre and a half of urine at each collection period. They'll be analysed for urinary ketones and then we will know how many calories are lost in the urine. NARRATOR: If Dr Atkins's theories were right the twin on the Atkins diet should be losing significantly more calories than the twin on low fat. In the morning the twins were released and the results were in. To prove you burn off significantly more calories breaking down the Atkins diet researchers expected the twin on Atkins to have lost at least a hundred calories more than the twin on low fat. And the Atkins dieter did lose some more calories this way, but a total of just twenty two.
Prof JOSEPH DONNELLY: Twenty two calories is too small to suggest that there really is anything going on.
NARRATOR: In other words burning fats and proteins appeared to take up hardly any more energy than burning carbohydrates. It seemed Dr Atkins's theory that you lose calories when breaking down his diet might be wrong. Next the researchers looked to see whether any calories were lost as ketones in the urine. The twin on the Atkins diet had lost less than a single calorie more than his brother on low fat.
Prof JOSEPH DONNELLY: This is not enough to suggest that this particular demonstration showed a difference.
NARRATOR: It seemed being in ketosis made barely any difference at all. Again Dr Atkins's theory appeared to be wrong. This came as little surprise to Donnelly.
Prof JOSEPH DONNELLY: I think the results are what we expected. There's no difference between the two diets.
NARRATOR: The research is at a very early stage, and not all studies agree. But in Donnelly's first examination of how the Atkins diet works proof of Dr Atkins's theories remains elusive. This leaves a mystery at the heart of the Atkins debate. People shed weight on this apparently limitless calorie diet. If calories aren't lost through ketosis or breaking down food what is happening to them? Clues to the likely answer came from the world's largest dieting study that took place in Britain last year.
JUDGE: Few have confessed to the charge of being overweight.
NARRATOR: Behind the scenes of a popular television series a groundbreaking study put four famous diets on trial. Only now are the full results of that study emerging. Horizon is the first to reveal this research. Three of the diets were conventional low fat, low calories diets. Weight Watchers, Slim-Fast and Rosemary Conley. The fourth was of course the Atkins diet. One of the most important parts of the study was that the dieters kept detailed diaries of what they ate. Only now have these diaries been examined. Joe Milward is an expert in nutrition and was in charge of analysing the data.
Prof JOE MILWARD: We had four groups with sixty in each, so that's two hundred and forty people. And we had planned to do three diaries. So that's more than six hundred diaries all together.
NARRATOR: All four diets performed similarly when it came to weight loss.
WOMAN BEING WEIGHED: Yes, yes,
WOMAN BEING WEIGHED: Wow.
NARRATOR: There was no mystery why the low fat, low calorie dieters were losing weight.
WOMAN BEING WEIGHED: Yes.
NARRATOR: They were eating fewer calories than normal. The puzzle was why was the Atkins diet just as effective? But when the researchers turned their attention to the Atkins diet diaries something intriguing began to emerge. The diaries showed that even though they could eat as much as they liked they were actually eating as few calories as the low calorie dieters.
Prof JOE MILWARD: They were losing weight because they were eating less calories. In exactly the same way as those going to the slimming clubs on their low fat diets were losing weight because they had reduced their calorie intakes. It was a simple matter of if you eat fewer calories you lose weight.
NARRATOR: So for all the talk of limitless calories the diaries actually showed the Atkins dieters were eating less than they would normally. For scientists this poses a whole new mystery. Why on earth should people who are allowed to eat all the calories they want choose not to? The suggestion is that the Atkins diet must influence one of our most fundamental instincts, appetite.
NARRATOR: This may be the secret to the Atkins diet. It works by controlling appetite. But what is it about the diet that kills hunger? Dr Atkins believed that it was due to cutting carbohydrates, but as yet evidence for this theory is so far inconclusive. There may be another reason. The Atkins diet is famous for its fat. Dr Atkins said you could eat as much of it as you like. Is it possible that fat could be suppressing appetite? To find out Susan Jebb and her team decided to run an experiment. All the meals in the study looked exactly the same, but there was a big difference. Half the food had liberal quantities of fat secretly added to it.
Dr SUSAN JEBB: We used things like spaghetti bolognaise or mousses so that you could because easily disguise the fat content of the food.
NARRATOR: None of the volunteers knew which type of food they were getting. But half of them were eating low fat meals, and half were eating high fat meals.
Dr SUSAN JEBB: What we told them is they could eat as much or as little as they wanted and they simply just had to ask when they wanted more food.
NARRATOR: If fat was the magic ingredient that switches appetite off, then the men eating the high fat food would fewer calories than normal to feel full. After four hundred and eighty six meals the results were clear. The fat was having the exact opposite effect. The men on the high fat food needed more calories to satisfy their appetite. They were actually overeating.
Dr SUSAN JEBB: What we conclude from that is that fat doesn't make people feel full. It doesn't trigger the sense of fullness and satiety that we believe is fundamental to appetite control.
NARRATOR: So fat wasn't the reason for the Atkins diet success. This just added to the mystery. There had to be another to explain why the Atkins diet made people eat less. The answer may have come from Denmark. This supermarket in Copenhagen is like no other in the world. It was built by Arne Astrup, a professor in human nutrition.
Prof ARNE ASTRUP: All the food items have a bar code on it, not for, not for pricing but for all the nutrition information with the calories, protein and carbohydrate.
NARRATOR: In this supermarket the check out assistant's not all she seems. She's a scientist, and everything in the shop is free.
Prof ARNE ASTRUP: When we announced actually in the television our University here was bombarded and the switchboard broke totally down and there were almost a thousand people who wanted to participate.
NARRATOR: Professor Astrup was running a study to discover the secret of appetite control. To do this he chose sixty shoppers and split them in to two groups. One group shopped for high carbohydrate food, the other group shopped for food high in protein, similar to the Atkins diet but low in fat.
Prof ARNE ASTRUP: One group should eat a lot of, of lean meat from shell fish, fish, poultry and lean meat, and dairy products. And the other group should eat a lot of bread, pasta, rice, fruit and vegetables.
NARRATOR: Both groups were told they could eat as much as they wanted. They should eat to satisfy their appetite just as Dr Atkins advised on his diet. The study ran for a whole year and the results were spectacular.
Prof ARNE ASTRUP: One of the groups was losing much more than the other group. I say it was four or five kilo more.
NARRATOR: When they looked more closely it was clear which group had lost so much weight. it was the group eating a diet high in protein. And the shopping lists revealed why.
Prof ARNE ASTRUP: We could see from the data that the reason why the high protein group had lost more weight was because they had actually consumed fewer calories throughout the study, despite the fact that they had just as the same free access to all the foods they really want to, to eat.
NARRATOR: At last the mystery of how the Atkins diet works may have been solved. It might have nothing to do with calories being lost. Probably nothing to do with ketosis. And apparently nothing to do with burning more calories. Neither does it seem to be due to gorging on fats. The secret to the diets success may be down to something completely different. Protein makes you feel full. Increasing the amount of protein in the diet may control appetite and make people eat less than they would normally. If this research goes on to be confirmed it will be a major advance for science.
Dr ERIC WESTMAN: The idea that you can eat certain foods and that it suppresses your appetite is a breakthrough, this is, this is huge.
Dr SUSAN JEBB: What's absolutely true is that people who consume large amounts of protein seem to feel fuller quicker than people who consume similar amounts of calories as fat.