High-protein low-carbohydrate diets: what is the rationale?

Dietary recommendations released by the large majority of international scientific committees and organizations suggest that the diet for the prevention and treatment of the most compelling health problems of our societies (obesity, diabetes, atherosclerosis, cardiovascular diseases and cancer) should be a diet moderately low in caloric content, low in fat content (particularly in saturated fat), poor in total cholesterol and rich in fibre. Despite this uniformity in official recommendations, alternative diets with low carbohydrate and high protein content continue to be extremely popular within consumers and patients. Recently, new studies seem to suggest that high-protein low-carbohydrate diets may have particularly positive effects on reducing body weight and other risk factors for heart disease. Gannon and Nuttall conducted direct comparisons of high-protein low-carbohydrate diets compared with high-carbohydrate low-protein diets in subjects with type 2 diabetes. They found that high-protein low-carbohydrate diets reduced fasting plasma glucose, 24-h glucose area under the curve and haemoglobin A(1c). On the basis of these results, a joint committee of the American Diabetes Association, North American Society for the Study of Obesity and the American Society for Clinical Nutrition suggested that a low-carbohydrate diet may be preferred to a low-fat diet for the induction of weight loss and glycaemic control in subjects with type 2 diabetes. What is the rationale? What mechanisms are involved?