The "freshman 15," like any weight gain, can be avoided by following simple dietary rules. The simplest is this: If you consume more calories than you expend, you'll add weight. So the first rule of thumb is to remain active, which guarantees that you continue to burn calories. Moderate exercise between classes and meals will work wonders. Even an activity as pedestrian as walking will not only keep your metabolism humming along, but it will also help relieve school-related stress (which can lead to ill-advised eating habits, both during and between meals). Just don't make a habit of walking directly to the cafeteria.
Eating is also central to other quintessential college experiences, such as creating new social networks and/or dealing with stress. Social circles are often formed around the act of eating, whether during meals at the dining hall or munching in the dorm rooms (what college student hasn't enjoyed a late-night pepperoni pizza with friends?). The stress of academics -- or missing home, or social setbacks -- can also lead to nervous snacking. If you have a mini-fridge in your room, find a study hall or library to do your schoolwork, and avoid the temptation altogether. If you keep munchies in your room, make sure they have some nutritional value.
When you eat is also important. Snacking after sundown (or gorging, if you've been out partying) is going to saddle your body with excess calories just before you go to bed. That's a sure-fire recipe for love handles. Instead, adhere to the time-honored maxim (generally attributed to American nutritionist Adelle Davis): "Eat breakfast like a king, lunch like a prince and dinner like a pauper." The concept is well-founded -- foods that you eat early in the day fuel your metabolism throughout the day. Those consumed late in the day, or at night, are more likely to be wasted and settle into fat stores.
If you do snack, keep an eye on portions. Moderation, again, has always been important component to eating -- and "grazing." In fact, snacks or "mini-meals" every three or four hours or so can actually help curb your appetite and over-eating at mealtime, says Diekman. "The challenge is really learning how to incorporate healthy eating and exercise into a schedule that is very demanding," says Diekman [source: Mann]. Foods rich in protein, such as string cheese or nuts, can ward off hunger between meals.
Diekman also suggests that college students avoid eating alone, as isolation can lead to eating disorders, such as anorexia and bulimia, which are the dark flipside to the freshman 15. Most institutions of higher learning have ample information on proper nutrition and smart eating habits. Avail yourself of these resources. After all, you're in college now. Be smart.