Same thread different title.
Smaller, more frequent meals. Cut back on the alcohol. Workout more.
I lived in the dorms for two years. The first was consumed by WoW, yes I'm a loser

, lack of exercise and poor eating. I gained weight as would be expected. The second I made sure I had healthy snacks in my dorm, peanut butter, canned tuna, milk, etc. Getting a mini-fridge and using it appropriately helps out a lot. I know at our freshman dining hall we were able to do takeout so you can store food for later if you don't want to buy stuff with your own money. I managed to get a pretty decent body back so what I was looking for at that point in time. As for alcohol, I only drink every once in a while, it's not required to have fun at college, or any other part of life, and if you think it is you need to work on your confidence and personality.
It all comes down to priorities, if you want to party all the time and drink then do that. If you want to have the body make the sacrifices in those things that interfere with it.