To address more directly the original point of the thread.
EAT!! eat big to grow. Eat mainly healthy foods, and get the amounts of protein, fat, and carbs that you need. Don't be afraid to eat so called junk when you really need the cals, and your trying to build.
There are plenty of times that I have a whey shake with some fish oil, and some dessicated liver, and then have some pizza to go with it. This is especially true after a heavy deads or squats day.
When it comes time for me to lose some weight, then the stroy will change. At that point I will become a bit more OCD about what goes in. However, with proper planning and the right choices it will not have to be drastic, and require that I starve.