food question

I have always been the kind of person who boasts about how much they can eat and stay skinny, lol cerebral palsy rocks! However, just discovered i'm not actually eating that much, like today, am planning a big meal down the pub or takeaway, but just discovered i've had nothing but three pieces of fruit and a glass of milk all day. On most weekdays I normally have a bowl of fruit and a bagel plus a good glass of milk for breakfast, faily decent evening meal but just just a piece of fruit for lunch... Just discovering this is amazingly little for my standards, but am not feeling particularly bad due to it... Is this a problem?