As every gym goer knows, gaining weight can be a good thing as long as the added pounds are in the form of bigger muscles and not a bigger belly. Whether you’re a skinny guy trying to pack on muscle or a not-so-skinny guy working to convert your body mass into muscle, bulking up isn’t as easy as it sounds. The trick is to feed your muscles and body by adding clean calories and nutrients so it can add muscle, not fat. This doesn’t mean you can binge on Domino’s pizza or stuff your face with a burger and fries without any guilt. While they may provide you with an extra dose of calories, the empty, fat-filled calories will show themselves in the form of love handles and a gut, not slabs of new muscle.