Since it’s introduction in the middle 1970’s, the Atkins Protein Diet has grown to be one of the most popular methods of weight loss. Low-carbohydrate, high-protein diets have been criticized by major health organizations including the American Heart Association, the American Dietetic Association, and the American Kidney Fund.
An article in this week’s issue of THE LANCET discusses whether the popular Atkins diet really does produce weight loss.
Over 45 million copies of the Atkins diet books have been sold, and the associated food products are also popular. Low-carbohydrate diets have been around since the 1860s, but the Atkins books are the most successful to date. Ad-libitum consumption of butter, fatty meat, and high-fat dairy products are advocated, while carbohydrate intake is restricted to under 30 g a day. Three randomised trials have examined the long-term effects of lowcarbohydrate diets. In the first, severely obese individuals were randomised to either an energy-restricted low-fat diet or an ad-libitum low-carbohydrate diet for 6 months. At the end of this period, individuals on the low-carbohydrate diet had lost more weight, but by 12 months no difference was noted between the two groups. The third study produced similar results, while in the second obese women on the low-carbohydrate diet lost more weight after 6 months than women on a comparative diet.
How does the diet work? Professor Astrup and colleagues state that when carbohydrate intake is severely restricted, glycogen stores and associated bound water are depleted, and so weight loss could mainly be fluid loss. However, X-ray absorptiometry studies did not show an excessive reduction in lean body-mass, suggesting that the weight loss is attributable to fat loss. The Atkins book claims that weight is lost because of increased energy expenditure, while Professor Astrup and colleagues suggest that it is more likely to be attributable to restriction of food choices, and the fact that protein has a stronger satiating effect than fat and carbohydrate.