Epistane will help you gain lean mass on it's own, but only while eating the proper amount, most likely allot, of clean food with the right macros. As you gain more muscle by eating more clean food, your body will by default use more calories and burn more fat. Once you start gainig lean muscle you will need to reevaluate your nutrition/caloric needs and readjust so that you can continue to gain even more lean mass and loose more fat. Taking the Slim X along with the Epi will just smash your appetite therefore making it harder to gain mass and loose fat.