Atkins-style diets cancel out benefits of weight loss

Following an Atkins-style diet may make you thinner but it won’t make you healthier, research suggests.

A study found that when women lost excess weight by eating a high-protein, low-carbohydrate diet they appeared to forgo some of the usual health benefits, including those linked to diabetes and heart disease.

Bettina Mittendorfer, a professor of medicine, who led the research at the Washington University School of Medicine in St. Louis, said: “It’s not that the metabolic benefits of weight loss were diminished - they were completely abolished in women who consumed high-protein diets, even though they lost the same, substantial amounts of weight as women who ate the diet that was lower in protein.”

Swapping bread and potatoes for steaks and chicken breasts - as promoted by diets like the Atkins, Dukan and Paleo diets - is supposed to help people lose weight because protein-rich foods are believed to make you feel fuller quicker.

The idea that a high-protein diet encourages fat loss rather than muscle loss has also entered dieting folklore - although the latest study suggests that it does not make much difference to this.

“When you lose weight, about two-thirds of it tends to be fat tissue, and the other third is lean tissue,” Mittendorfer said. “The women who ate more protein did tend to lose a little bit less lean tissue, but the total difference was only about a pound. We question whether there’s a significant clinical benefit to such a small difference.”

The study, published on Tuesday in the journal Cell Reports, involved 34 women with obesity who were aged 50 to 65 years. Although all of the women had body mass indices (BMI) of at least 30 (30 or more indicates significant obesity) none had diabetes.

The women were divided into three groups: a control group, who were asked to maintain their weight, a second group who followed a weight-loss diet with recommended daily protein intake (0.8 grams per kilogram of body weight) and a third group who ate a high protein weight-loss diet with 50% extra protein. By the end of the 28-week study all the women had lost roughly 10% of their body weight.

“We found that women who lost weight eating a high-protein diet didn’t experience any improvements in insulin sensitivity,” said Mittendorfer.

Insulin sensitivity is an important health measure because in many people who are overweight insulin becomes less effective at controlling blood-sugar levels, which can ultimately lead to type 2 diabetes.

The women who ate the recommended amount of protein saw big benefits in metabolism, led by a 25 to 30% improvement in their insulin sensitivity. Such improvements lower the risk of diabetes and cardiovascular disease.

The scientists said it was not clear why insulin sensitivity didn’t improve in the high-protein group, but suggested that it could be linked to the body essentially having to flush out “excess fuel”.

The scientists also said it was possible that the high protein group did improve on other health measures that they had not studied, such as joint pain.

Mittendorfer said she was concerned about an increasing number of foods being marketed as high in protein. “We push protein into foods that are not traditionally high protein ... like cereals,” she said. “Potentially this could be harmful.”

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