THE high-protein Atkins diet works not for the reasons its inventor claimed, but simply because people eat less.
Several studies have shown that a high-protein, low-carbohydrate diet does result in weight loss, though there are worries about the long-term health effects. Robert Atkins, who invented the diet in the 1970s, claimed it works because digesting protein burns more energy than digesting carbohydrates and because calories are lost in urine through a process called ketosis.
A series of unpublished studies highlighted last year in the BBC TV programme Horizon suggest that neither of these reasons is correct, and that instead people actually choose to eat fewer calories when deprived of carbohydrates. Now Guenther Boden at Temple University School of Medicine in Philadelphia has provided further evidence.
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He put 10 obese volunteers with adult-onset diabetes on a low-carbohydrate diet for two weeks. The study is the first to keep dieters under constant observation and to record calorie intake and energy expenditure.
Boden found the volunteers reduced their intake by an average of 1000 calories a day to around 2100 a day, even though they were allowed to eat as much low-carbohydrate food as they wanted. They chose to eat an amount that, if continued, would maintain them at an ideal weight for their height. Their blood glucose levels and insulin sensitivity also improved dramatically (Annals of Internal Medicine, vol 142, p 403). 鈥淭hey dropped 1000 calories because they didn鈥檛 want to eat more,鈥� Boden says. 鈥淭hey loved the diet. They loved to eat bacon and eggs, and sausages and that sort of thing.鈥�
Eric Westman at Duke University in Durham, North Carolina, says the study helps to show why weight loss occurs, but it is still not clear if the diet is effective in the long term, or what the long-term health effects are.
