Doctors attack 'benefits' of low-carb diets

John McDougall, an advisory board member of Physicians Committee for Responsible Medicine (PCRM), explains in his letter to this month's Mayo Clinic Proceedings​ (vol 79, no 3, p431) that low-carb diets can result in a metabolic state called ketosis that also occurs during severe illness, resembling the common side effects of cancer chemotherapy such as fatigue, nausea, and loss of appetite.

People on low-carb diets who become ill enough to experience loss of appetite are taking in less fat and cholesterol, since they are consuming less food overall. It is this same mechanism that results in cholesterol levels falling in cancer patients, he suggests.

The low-carb Atkins diet has seen a strong following in the UK over recent months, with an estimated 3 million people changing to the regime to lose weight. Although some suspect it is merely a fad, the diet has stolen sales from other weight management products in North America, including the leading brand SlimFast.

There is rapid development of 'low-carb' brands in the US, with some of these making recent entries to the UK.

However nutritionists and medical experts continue to debate the health aspects of the diet, with many citing evidence to show that high-fat, low-carbohydrate dieters risk clogged arteries, heart attack, colon cancer, and kidney failure. Studies also show that even one fatty meal can increase the risk of a cardiac event immediately following the meal, says Dr McDougall.

"A better approach is to encourage people to eat foods that promote both ideal body weight and health--those from a high-complex carbohydrate, low-fat diet,"​ he said.

"For example, people living mostly on high-carbohydrate rice and vegetable dishes in Asia are trim throughout their lives with almost no risk of heart disease, diabetes or our common cancers."​