I had the same issue he was basically on a liquid diet but he was four so I was very worried. His appetite increased and he began adding foods when we put him on Risperdal which is a drug used for autism. One of the side effects is an increase in appetite which can be problematic if they are in their teens but in this case it was beneficial for my son and he began eating more and adding new foods to his diet.

AUtism is Sensory Overload.
Pediasure is full of everything he needs, so I wouldn't get too upset of his eating habits. Just keep trying.

At least I know there is hope.

Thank you I just worry he won't ever eat or get off the bottle