Holy crap, has no one mentioned cardio...
It is difficult to gain size (muscle mass) and lose fat at the same time, but without cardio, fat loss is impossible. Dietary restriction does not reduce fat (in those looking to lose that last 10 pounds), and in more instances then not, makes the body more resistant to fat loss.
The key is eat less calorie dense foods (vegetables). You will have a full plate packed with nutrients etc., feel like you ate a full meal, and more importantly, get the ruffage you need to keep your intestinal tract moving.
As for the gas problem, keep a diary for a week of what you eat, when you crap, when you feel bloated etc. There may be a trend that you are not aware of. Just as lactose intolerance creates havoc, some people have different reactions to different foods. A small change can create a massive improvement.
Also, a change in diet can create problems, but the body is amazing in that it can adapt to changes. Give any dietary changes a couple of weeks (at least) evaluation before scrapping a regiem.
