Buffets are the cornerstones of on campus meal plans. Try to avoid these places as much as you can. Once you're in there, self control can only go so far. You'll be flooded with smells of all sorts of goodies and be tempted to eat them all. Instead, try going to a cafeteria that you pay for what you eat. Once you're full, you'll be less likely to eat more.
Step2
If you must go to a buffet, use a big plate for salads (small plate for everything else) and make sure you eat the salad before the main entree. This way, you'll eat more low calories foods and less high calorie ones.
Step3
When you eat, drink water instead of soft drinks. Many people don't know how many calories soft drinks really have. One cup can have more than 130 calories and that's only in 8 ounces. The cups that you'll be using can be around 16-24 ounces. This can save you hundreds if not thousands of calories per week and make a huge difference in the long run.
Step4
Instead of driving or taking the bus to class, walk or ride your bike there. You'll be exercising and getting to class at the same time.
Step5
Exercise might be the most important step in trying to avoid weight gain. If you eat too much, exercise is the only way to burn off those extra calories. You have a free gym at your disposal so you might as well use it.
Tips & Warnings
You can get more help by reading and posting to the diet and exercise forums that are linked below.
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