the ideal proportion of macronutrients in weight loss diets is currently under debate. there are evidences indicating that a higher proportion of protein during weight loss diets enhances the loss of body weight and fat mass, and reduces the loss of lean body mass. nevertheless, the responsible mechanisms for these effects have not yet been fully elucidated. furthermore, studies that evaluated the possible side effects of these diets on the renal function and on the nutritional state of calcium have shown inconclusive results. therefore, this article has the objective to convey recent information about the effects of high-protein diets in the regulation of the body weight and body composition, besides its involved mechanisms, and its effects on the renal function and on the calcium nutritional status.