Q: How do I keep the freshman 15 off? 

I don't think there's one way to do this/one method that works for everyone. I will say that one thing that I wish I would have done differently my Freshman year of college was establish a routine early on. I should have been more firm about waking up and getting my workout in before having a full day, going to sleep at a reasonable hour, and not late night snacking!! I think these are the things that will get you!! Also, maybe check out my "Feel Good Plan" as a good guideline? For some people, it really helps!! I hope this was helpful! :)