50% of calories should come from complex carbohydrates (whole grains, fruits, and vegetables) <35% should come from fat (with no more than 10% coming from saturated fat). 20% should come from protein.
protein is the most filling, but you shouldn't go over board with it. Your body needs carbohydrates in order to function correctly. When you start an adkins like diet, your bod begins to use ketones instead of glucose as an energy fuel. This makes your blood more acidic and will make you hazy in the head. You may notice discoloration of your skin, a sweet smelling scent to your breath, and some mild hair loss.... increasing some protein for weight training isn't bad, just don't cut out your carbs.
If you are truly concerned about your diet, talk with a dietitian, that's what they are there for. Make sure they are a registered dietitian (they have a 4yr degree at a min from a university), a nutritionist may or may not be a dietitian so be careful. Often, nutritionists have no education in nutrition at all, or maybe they took a semester long course, but they won't be of any use. Unless your physical trainer is also a dietitian, be careful with their recommendations. Technically, all they can recommend doing is what is listed on the mypyramid.gov website, but they often ignore that rule...
No dietitian will recommend that you cut dairy out of your diet. For many it's a good source of vitamin A, D, and calcium. There are other sources, but dairy is one of the easiest to obtain the recommended amounts. People under the age of 30 really should try to get the RDA of calcium because this is when you are going to be reaching the max amount of bone calcium, after that you begin to depleat it. The protein in the milk will also help keep you full, so a serving of milk will help reduce hunger pangs as the morning goes on. Just make sure it is 1% or skim, no one over the age of 2 needs whole milk, and no one really needs 2%
like other people said, increase the amount of fruits and vegetables you eat. Not only is it good for you, it's going to reduce the risk of cancer and cardiovascular disease as you age. I keep baggies of carrots in the fridge with cellery. I'm also one to slice up peppers. If you want to, slice up a couple of apples, mix them with some oranges so the vit C will prevent the apple from browning (this seems to disgust people for some reason) and just munch off of that for the day or so. I also like to slice kiwi up and keep them in snack bags along with portioned out grapes. When money is tight, I buy frozen mixed berries and portion them out in baggies. The night before I put them in the fridge to defrost. They aren't as firm, but they still taste good.
Also be careful about limiting the amount of calories you consume. At one point when I was tryig to lose weight, I was burning about 800 calories in cardio at the gym and was limiting myself to about 1800 kcal a day, this actually sent my body into starvation mode and I quit losing weight. I ended up eating a little more and toning down my cardio some and started to lose weight again a little while later.
Meet with a dietitian and they can help plan a diet for you... or visit mypyramid.gov and they can help calculate kcal and help with keeping a good diet in correlation to your physical activity
oh and to give help w/ cardio during the winter. Climb stairs in the building. I know the lab building on my campus has areas where the stairs are rarely used. I am sure you can find someplace on campus that you can climb stairs. If anything walk around the university center, I'm sure it's large, or if anything see if there are any cheap gyms around your campus. I go to all american gym and it's like $19 a month... not every place has something like this, but you can at least see.
