..when i said i was gonna party after i turned 21, i wasn't BS'ing, i guess it all caught up right away though
Here's a very effective tip that worked extremely well for me. Remove, as best as you can, sugar and gluten (especially wheat flour) from your diet. Admittedly this can be a bit of a challenge given the state of the average Western diet, but, from personal experience (I'm on the thin side and given to a paunch as well) it delivers incredible, and fast results. Especially when accompanied by an exercise program that emphasizes constantly varied, functional movements and high intensity. I was never one to have a well defined musculature. Now, at an age that many would consider "getting on a bit," I can actually see definition in my abs, chest, shoulders and arms when I'm sticking to my program.Google "Paleo diet". You'll find it a bit extreme at first blush, but even a nominal stab at applying some of the principles will deliver good results. Good luck!
if your brave enough....do P90x...(google it)...try the lean version. You will lose your belly and change your body, and life.