My girlfriend has a 2.5 year old who eats next to nothing. She is light in weight, doesn't need a lot of sleep and the pead's aren't worried about her as she is happy, talking, playing etc and they think eventually she will eat when she is ready. She literally lives on the smallest amount of food over a week ie 2 weetbix a day. It has been a constant worry for her mum but she has all the energy in the world - must be good air she's breathing!