> When one has a sedentary lifestyle, and turns to consistent sport activity, it's very typical to quickly lose fat and gain muscles for some time I've lived t

> When one has a sedentary lifestyle, and turns to consistent sport activity, it's very typical to quickly lose fat and gain muscles for some time I've lived this experience. Exercise without diet will make you gain weight because muscles grow, and they're heavy, so your fat percent changes. This doesn't mean less fat, just a change in the ratio of muscle against fat. Stored fat is a vast energy reserve, and exercise alone will not deplete it. Even if your metabolism increases because of your added muscle, it will eventually reach a new equilibrium. Exercise burns energy at a much, much lower rate than food can add it.