I'm not a doctor, or anything, but my best advice is to worry more about getting healthy than anything. I went to college last year and because I didn't have a car, I walked everywhere and lost weight. So simple things like walking short distances like to a friends house instead of driving and drinking water instead of soda can help a lot. Also, take the stairs instead of the elevator and instead of McDonalds, go to Subway for meals. It's healthier.