I'm going into my third semester at college and I haven't worked out since my first (save for running to catch the shuttle every once and a while).  Guess what? I'm still 5'4" and 109 freedom units.  When I noticed that I gained enough weight (was my goal, I was severely underweight at the beginning of college) I cut back.  I switched to diet cola, and cut the amount of desserts I was eating.  It wasn't hard.