Index glycémique, index insulinémique et régulation du poids corporel

It is commonly thought that diets eliciting low blood glucose and insulin responses result in increased satiety, reduced weight gain and/or increased weight loss. These effects have also been ascribed to foods with a low glycemic index (GI) and/or low insulinemic index (II). Evidence is accumulating that low GI foods may be more useful for weight loss than moderate reductions in carbohydrate intake, but the mechanisms for this are not clear. There are many different reasons why a food may have a low GI, such as the presence of fructose or dietary fiber, the nature of the starch, or the particle size; these factors may not influence body weight to the same extent. The results of studies suggesting that low GI foods increase short-term satiety and reduce short-term food intake are inconsistent and often confounded by factors other than differences in blood glucose response. Thus, it is not possible to ascribe the differences in satiety/food intake observed to differences in blood glucose per se. High blood insulin is commonly thought to cause an increase in body weight because it promotes fat storage rather than fat oxidation. However, there is evidence that adults with high blood insulin have lower food intake and gain less weight than those with normal blood insulin levels. Low GI starchy foods may help to regulate body weight because of a reduced rate of starch digestion leading to reduced energy absorption and increased colonic fermentation which, in turn, may have direct and indirect effects on the gut, pancreatic and adipose hormones which regulate energy intake and energy expenditure.