One of the limitations of research studies that test macronutrient-limited diets is that they pit one diet against another. A study that tests a fat-limited diet vs. a carb-limited diet is testing only those two diets.The results may show one those two diets to be superior to the other with respect to particular parameters, but it doesn't mean that the superior diet of the test is the best diet of all possible diets. Alternative diets are available that don't rely on limiting a macronutrient such as fats or carbs. They use other approaches, such as maximizing micronutrient density and fullness factor per calorie and offer a greater degree of freedom in selecting foods for optimal micro and macronutrient profile for weight loss (or weight maintenance or weight gain). The calorie density approach: http://www.jeffnovick.com/RD/Articles/Entries/2012/5/20_A_Common_Sense_Approach_To_Sound_Nutrition.html Another example is a diet that attempts to maximize micronutrient and fullness factor per calorie. The website below describes an approach where foods are plotted on a map that shows the micronutrient and fullness factor. The upper right quadrant represents high micronutrient and fullness factor and is the preferred region for those seeking weight loss. The lower right quadrant is nutrient dense and low fullness factor and preferred for those seeking weight gain. http://nutritiondata.self.com/topics/better-choices-diet