I also recently graduated and I definitely struggled in the college dorms. My advice is this:
-Alter your big meals of the day. Usually dinner is the biggest meal, but I actually found that in our dining hall, there were more healthy options during breakfast. I would get things like scrambled egg whites or a big egg white omelet with veggies, lots of fruit, and whole grain toast with a little peanut butter. Definitely focus on filling foods and make breakfast the biggest meal of the day once in a while. It keeps things exciting, especially when I would tend to get sick of the same things at each meal. Also, it definitely helped me make it through class all day. Sometimes I'd just have a yogurt for lunch and then a healthy dinner. Also, starting the day off healthy puts you in a good mood and can set the tone for the rest of the day.
-Second, avoid empty calories in alcohol. This is definitely a will power thing too, but offering to be the DD can help. If you do drink, stick with low calorie options and avoid sugary drinks that add empty calories.
-Last, keep filling foods around. Sometimes, I'd eat because of temptation, but a lot of times, I would go too long without eating, end up starving, and binge. Keeping things like fresh fruits and veggies, air popped popcorn, and turkey hot dogs with lite whole wheat buns (100 calories for both hot dog and bun) gave me options of something quick and easy to satisfy any food craving (sweet, salty, protein).
Also agree with everyone's advice on water and willpower. Those are definitely things I know we all struggle with (or we wouldn't be here). Good luck and enjoy college!