How much weight could I lose on this plan?

I have a much less complicated plan for you. Cut down your carbs, and if you do eat carbs make sure they are complex carbs such as, brown rice, oatmeal, whole wheat etc. Switch potatoes out for yams. (Yams are better for you anyway, and it saves having to put butter or salt on a baked potato.) Increase your lean protein, fiber, as well as your vegetable intake. You say you are already mostly muscle, so if you are looking to lean out, up your cardio! Running, swimming, kick-boxing, dancing, anything that gets your heart racing for at lease 45 minutes a day. Of course, keep up your lifting/muscle workouts, but increase that cardio! Oh and you should see and feel results within a few days! By the way, cutting your carbs will be hard and you will likely become grouchy (if you cut them out completely) and you will have carb cravings, but after 3 days you'll feel better! Good luck!