Questions about food!
Hey man, good to see you taking an interest in the dietary side of bodybuilding/fitness training. For starters, how much do you weigh, what is your goal, and are you trying to build mass, build muscle, or lose weight?
Im 5'8, 160 and on a 1200 calorie intake a day. I had gone to the dr to determine my intake and body mass etc. Its different for everyone.
So, for slimming down most of what you're going to need to do is cut unhealthy foods out of your diet, such as sodas and fast food. Sweets too. Fast food is almost always extremely unhealthy, high in saturated fat and trans fat, very calorie-dense, and should thus be avoided by everyone. Soda is extremely calorie-dense, has no nutritional value, and for various reasons, you shouldn't be dumping massive amounts of simple sugars into your system. There is debate over if diet soda is neutral or still bad for you; my suggestion is to limit it, too.
As for building muscle, a large part is protein but you will also need regulated amounts of carbs, fats and etc. Depriving your body of any one thing is not good, just be sure not to over-indulge.