Even if you aren't hungry, you should try to eat something light, such as a yogurt, some cottage cheese, fruit, etc. You don't need to eat a lot, but you should have something.
If you have to skip a meal, it should be dinner.... I eat a good breakfast and lunch, but at dinner, all I have is an apple with peanut butter, a yogurt, protein shake, etc.
Every meal should contain protein, complex carb and fat.