The answer may surprise you. A must read for parents of young children, to ease your mind and stress at meals. ^^^ This has an eating "cheat sheet" which wonderful breaks down different general portion sizes and really makes me feel better.
If I could get my toddler to eat anything besides chicken nuggets, hot dogs & PB&J. Toddler Lunches: Going Beyond Chicken Nuggets, Hot Dogs, and PBJ Sandwiches. A good "go to" list when you are too tired to be creative:)