TVScope: The infamous Atkins diet is known to one and all as the "celeb" diet. Not a week passes but we hear of some film star who has lost half their body weight, thanks to the wonder diet devised by Dr Robert Atkins, writes Marion Kerr
The BBC 2 programme, Horizon, looked at the controversial diet and analysed why - though it seems to make no scientific sense - the Atkins diet works. Although it's been around for over 40 years, it has only recently grown in popularity, with the latest edition - The Atkins New Diet Revolution - selling more than 17 million copies worldwide.
But first, a quick update on the origins of this controversial diet. Dr Bob Atkins, cardiologist and one-time-fatty, developed a personal diet which did not restrict the foods he liked. Contrary to scientific and medical advice which promoted low-fat eating, he found that he lost weight by eating fats while cutting out all carbohydrates. And it worked so well for him that he encouraged his overweight patients to follow his advice with good results. The "Atkins diet" was born.
But despite its initial success with the overweight, it was not warmly welcomed by the scientific community. The principal reason was that the diet went against the first law of thermodynamics, which states that energy can neither be created nor destroyed. If you eat more calories than you need, the theory goes, you put on weight. But the Atkins diet seemed to say you could eat all the calories you wish and still lose weight. The question is, where did the extra calories go?
Atkins needed an answer if his diet was to gain credibility. So he came up with the theory of "ketosis". Ketosis is the result of the way fat is broken down in the body. Compared with the breakdown of carbohydrates, which is relatively simple, fats have to go through a much longer, more complicated process in order to be used for energy.
Atkins claimed the body needed extra calories to process the fats consumed. In addition, he theorised that additional calories were excreted from the body through the urine and breath. Which nicely explains why people following the Atkins diet always suffer from halitosis!
Horizon commissioned a study to look at the Atkins explanation, which saw identical twins locked away for two weeks, one on a low- fat diet, the other on the Atkins. Their energy consumption and expenditure were measured over the period and, like the subjects, were found to be identical.
But Horizon didn't leave it there. Still searching for the answer, the programme looked at a recent British weight loss experiment involving 240 participants who were divided into four groups. Three groups followed different low fat-diets. The fourth group followed the Atkins diet. In addition, participants were required to keep a detailed diary of the food consumed and energy expended. Each of the four groups lost weight, but it was only when the diaries were analysed did it become clear how the Atkins group won the battle of the bulge.
Protein, it seems, suppresses the appetite. So, although Atkins dieters are allowed in theory to eat as many calories as they wish, the high-fat protein foods they consume switch off their appetite and they in fact consume less calories than they needed, leading to weight loss. Simple!
The mystery of why Atkins followers lose weight has finally been solved. But doubts remain about the long-term health benefits and risks of the diet. The scientific jury is still out on whether large quantities of meat cause kidney problems; if fat has an impact on breast cancers; and whether protein is bad for the bones.
Will I be joining the ranks of the Atkins devotees? There's only one answer to that... Fat chance!