Buy your own low-fat salad dressing and take it to dining room with you. Ask the server to not add the sauce onto the entree, and ask for no cheese on the sandwich. You may just have to work around the food offered. If you can, take fresh fruit and cereals back to your room for healthy snacking. If you have a refrigerator in your room and maybe a microwave available, stock your room with healthier convenience foods.
Next semester sign up for a lower number of meals per week.
It is still important to eat with your friends in the dining hall, but you may have a healthier breakfast and lunch in your room. Buy baby carrots, yogurt, apples, grapes, oranges, etc. for the fridge. Start a movement. Put ideas in the suggestion box. Talk to the food service director about you and your fellow students' concerns.