The roles of different macronutrients in regulation of appetite, energy intake and adiposity

Abstract Over-consumption of calories rather than decreased expenditure is the most likely cause of the obesity epidemic. The reasons for this remain disputed with all the main macro-nutrients (fat, protein and carbohydrate) being implicated by different authors. Stimulated intake by declining dietary protein (protein leverage) may be important. The carbohydrate insulin model pins the blame for the epidemic on intake of refined carbohydrates. Yet others blame the high energy density of fat. In mice (and probably humans) a combination of around 50-60% fat, 10-30% carbohydrates and 10-20% protein (by energy) seems to maximally stimulate food intake and results in the greatest levels of adiposity. Humans find this combination most rewarding. Any diet which moves away from this combination are likely to promote weight loss. Why this combination stimulates intake so much is unclear because it does not correlate to any ancestral adult human diet, but it is similar to human milk.