My best guess since you're living in a dorm and sharing space in the fridge would be to stock up on fruits and veggies that can be contained OUTSIDE the fridge or pantry. Processed foods (though cheaper and longer kept) are really not your best friend. Natural foods are. Not discounting the necessity for a granola bar or protein bar here and there when you're in the hurry (they're certainly better than not eating at all), but planning to eat sensibly will work wonders for you and shouldn't be too difficult for you to maintain.
Fruits- fruits are naturally packaged in their own skin, peel, etc. so if you've got a market nearby, try and make two trips a week to pick up some fresh fruits like small oranges (mandarin oranges are incredibly small so they're fewer calories but peel incredibly easy and make a perfect snack), apples, bananas, etc. Berries are fantastic and portable as well. The trick to keeping them longer? Don't rinse them until you're actually ready to eat them. They'll last longer outside the fridge that way.
Veggies- probably my most difficult thing to master, but that is my own issue. Cucumbers take 20 seconds to slice, carrots can be cut up or bought in those little baby size cuts...shoot, I used to just wash a whole cucumber and just start eating it whole when I was in college! Currently, I, too, cut/dice/chop my veggies when I first get them home and then throw them in the fridge for later use during the week. I love red, yellow, orange and green peppers for a crunchy and hydrating snack. They'll either become a cold snack food for the week or end up in a stir fry. I know you can't cook for yourself too much, but I've started grating asian green pumpkin, mushrooms, carrots, zucchini, etc into my meatloafs or lasagnas to add veggies in so I don't have to worry about veggies while we're enjoying the meal. Plus, my toddler has no clue tee hee...
As far as carbs, whole wheat options are the best and just watch portion size (literally- don't make a plate of pasta, eat it as a side dish and try to make veggies the largest portion of your meal). My doc told me that a healthy cereal and piece of fruit is best for breakfast, but I always like some sort of protein to help keep me satisfied as well (glass of milk or slice of cheese).
For proteins, you'll have to get creative since you're not in the best position to cook chicken, meat or fish for yourself. You could always boil a few eggs to have as a snack, salad topper or to mix with light mayo for egg salad sandwiches, but by 'creative', I mean that canned options such as tuna, albacore tuna, and salmon are your best options for college life (although the trade off is higher sodium content- keep an eye on that). There is also canned chicken which you can make into a chicken salad and as a topper for your salads. Another fantastic protein source that comes form a can would be a bean salad: really, any beans besides baked beans. I take a can of each black, red kidney and diced tomatoes, 1/2 can of chick peas (these are high in fat, good fat, but high in fat nonetheless, so increase or decrease as you'd like)and mix them together with a splash of olive oil, 1/2 cup of diced red onion, 1 cup diced peppers--red, green, orange, and/or yellow-- and any dried spices you'd like. I used parsley, thyme, and basil or whatever I have in the house that seems tasty. This is so easy and doesn't need to be refrigerated until after you put it together. It's a fantastic snack and quick eat, and you can make a few days worth at a time. The fact that there is a good mix of protein, fiber, fat and carbs in this will really help you feel satisfied and energized.
In terms of dieting for weight loss, calorie intake should be monitored, but if you're eating balanced, whole foods and getting plenty of fruits and veggies, then you'll find that is is more a matter of portion size than calorie counting (at least until you get closer to your goal weight :-/).
Good luck and hope I have helped.
