I'm trying to lose fat and gain muscle (but mainly lose fat and just tone up overall), so I got some 100% whey protein powder. This powder is 80 calories per serving, with 20 grams protein, 1 gram carbs, and zero grams fat. So why not use this for weight reduction? Isn't this as filling a breakfast or snack you can get for that amount of calories (since its so high in protein and almost no carbs/fat)? If I use this product, will I gain weight?