It's pretty much a proven fact that diet alone or excercise alone don't produce weight loss results - you need to combine them! But healthy eating never hurt anyone - and I'm sure it will only help! Try to get in some excercise - even if it's just walking to and from class, always taking the stairs instead of elevators, and lifting free weights if you have them!
When it comes to food choices - like someone says - moderation is key!! Usually, you can eay anything as long as you eat a single portion and not more! It also depends on the type of body you have and how you process food. For example, carbs and I don't get along - if I eat too many I gain weight. People always think fruit is super healthy (and it is - compared to a hot fudge sundae

) but fruits have natural sugars in them and as we all know sugars = carbs. So try not to eat too many fruits - but veggies are fair game! Limit bread/pasta/potatoes to just 3 servings a day. Avoid pop (or soda or "coke" as wierd people in the south like to call it

) and fruit juice - again, lots of carbs! Drink water drink water drink water!! It helps fill you up so youre not as hungry and keeps you hydrated which is so important!
I totally recommend reading Body for Life, the diet is a good one to follow, but I don't do the excercise routine b/c I like my own much better! Good luck