Carbohydrates as macronutrients in relation to protein and fat for body weight control

Abstract

There is a need to explore how to increase the satiating power of the diet, so that people feel full with less energy, and by this means reduce their spontaneous energy intake. A reduction of dietary fat from typically 37–27% of total calories will produce a weight loss of 3–5 kg over 6 months, depending on the amount and source of carbohydrate and protein in the diet. The weight loss is sustained as long as the diet composition is adhered to, and evidence from the large Women's Health Initiative dietary intervention trial showed that those who complied with the fat reduction without any energy restriction maintained a lower body weight over 9 years than those on a normal fat diet. The predominant mechanism for the weight loss effect is the lower energy density of the fat-reduced diet, so that this diet provides more food volume and weight for less energy, and hence greater satiating effect than a higher-fat diet. It is likely that the diet also provides a metabolic advantage in individuals susceptible to obesity by a genetically determined impaired ability to rapidly adjust fat oxidation in response to increasing the dietary fat content. The carbohydrate source is also important for the diet's effect on body weight, that is, whereas sugars in solid foods seem to have the same satiating effect than starch, sugar in drinks seems to exert a low inhibition of subsequent food intake. Newer research indicates that increasing the protein content at the expense of fat and carbohydrate might offer a way to increase the satiating and thermogenic effect of ad lib diets, and facilitate weight loss and maintenance.