Hey pal. I think the way you should be going is to adopt a healthy diet first. It sets the foundation for a healthy lifestyle which will support your workout and body changing goals, not to mention being immeasurably good for your overall health.
Find out your calorie needs. Find out how much you do eat (protein, carbs, fat and total calories) and how much you should eat.
A good online resource to use for this is nutritiondata.com. Also, in the beginner’s forum, there is a sticky called “You are a beginner p.2” (or something close to that). It has links to very good articles on the subject of nutrition.
Once you know that, it’s time to put it into a meal plan. This is the difference between knowing what’s right and f’n doing it!
Make meals that you can prepare yourself. Think about what you have access to at home, at the university cafeteria etc. Think about what your culinary skills will allow you to prepare.
I’m not much of a cook so I stick to things like tuna burgers (whole wheat bun, 1 can of tuna, two slices of cheese), raw eggs with milk etc. Does this sound like you? Hey, you can make healthy meals no matter what you cooking skill level happens to be.
Write it out! Writwe out how much protein, fat etc each meal gives you. Total it up. Put it on your fridge. Put it on your bedroom wall. Carry a copy in your jacket pocket. Many people have posted theirs on this site. You could review those, and incorporate them into your own plan (it need not be much work).
When I was your age, I knew nothing of nutrition. I spent years and years trying to bulk up but never knew how to run the diet. Oh if I could turn back time
Really, do youself the favour and put this into action now. You’ll slim down, muscle up and then the girls won’t be able to leave you alone It’s worth it!