I graduated just a couple years ago, but still act like a college student sometimes
I like the water bottle idea mentioned above. It especially helps because it keeps something in your hand and gives you something to do instead of grabbing snacks. The best thing to do it plan, plan, plan. If you know you're going out then plan to eat lower calorie meals throughout the day. Plan what you'll have for lunch before you go. I have to avoid bags of things because I will eat until the whole bag, or can is gone. Portion things out. If you go to a friends room look at the calories on the munchie before you eat it- that usually helps deter you. It helps you think about- would you rather have these cookies, or an entire meal later? And know that there will be other people that tell you to just eat whatever bad snacks or food they are having and stop worrying about it or will try to deter you but you have to be strong in your decision to eat healthy and be proud of it. Other people sometimes try to make themselves feel better by not being the only one eating something "naughty." Stick to your guns! You can do it!