And some people think that it's as simple as calories-in vs. calories-out and completely ignore the effect of hormones on our hunger and energy levels and the root cause of why we tend to be sedentary and overeat. The main culprit is insuline, we've known this for decades. If you can keep your insulin levels under control by restricting carbohydrate intake, and increasing natural dietary fat intake and eating moderate protein your body will naturally tend to suppress your appetite and you'll eat less and become leaner until you get close to your ideal weight.