Limiting carbs and limiting calories is the real secret of weight loss. You have to limit carbohydrates to limit fat storage. The more carbohydrate in your diet, the easier it is for you body to store fat. You have to limit carbohydrates to limit hunger. The less carbohydrate you eat, the less hungry you are. Carbohydrates release insulin, the hormone in your body primarily responsible for hunger and fat storage. But you also have to limit the number of calories you eat. You absolutely, positively cannot freely feed on protein and fat, and expect to lose weight. If you want to lose weight quickly enough, to stay motivated enough to stay on your diet, you probably can’t eat much more than 1500 calories a day. 1000 calories a day is better. 500 calories a day is tough to stay on, as it’s hardly any food.