Clearly this isn't what she's doing. Obviously it been proven you can lose weight eating nothing but MacDonalds if you're doing it right. But she's A, not hitting the gym, B, peanut butter is known, along with bananas, eggs, steak, bread, as a BULKING FOOD. As in, if you're in a bulking period, it's great to help add quick weight because of the amount calories vs. portion size. This isn't fat logic it's a basic numbers game.