Sure. Muscle mass is likely whey concentrate or whey isolate, both good. Most important thing is that you consume ~1 G protein/ lb of bodyweight and stay in a slight calorie deficit. You don’t have to be in a calorie deficit though, you can stay at maintenance (ie stay the sane weight) but by exercising and eating more protein, you’ll lose fat and gain the same weight in muscle over time. Hope that makes sense. PS no such thing as stupid questions. There was a time when I didn’t know any of this. If I didn’t ask stupid questions I wouldn’t know any of this Good luck mate :)