There is a child Psychologist called Tanya Byron and she is brill with kids.
I watched her programme about a wee guy that would not eat and it was the parents who were the problem...as they made a big fuss of washing your hands all the time, cleaning up every time he spilled something, dropped something...so the wee guy decided eating messy foods was not worth all the hassle, so tried to live on biscuits and dry foods.
She made eating fun....made a mess, did not make a big thing of clearing it up...days later, he was eating like any normal child.
I had a problem with my son eating.....I then noticed (some one told me!) it was my problem and if he does not eat...it is his problem as he is the hungry one not me...I had to learn not to make an issue of it.
It was a control issue...he wanted to control the situation, by always leaving some and I was having none of it!
Lesson learned....if he wants to leave some...upto him, but can not complain of being hungry 5 minutes later..