How can weight gain increase my appetite?

An increase in muscle mass can lead to both weight gained on the scale as well as a larger appetite. Muscle tissue is metabolically active and requires additional calories to sustain it. This is why it is helpful to weight train and build muscle when you want to lose body fat. Your metabolism will speed up and your body will burn more calories, even when you are not active. This will allow you to eat more and still lose fat. Your body knows that it needs more calories to fuel the additional muscle and will stimulate your appetite so you can adequately supply it with what it needs.