B.M.
Have you talked to his dr? Do they also worry about his weight? Do he has sensory issues with food? Did you know they actually have food therapists? I did not know this until a few years ago! They can be very helpful. I might be hard, but whatever he will eat, let him. My daughter has autism and will only eat crackers and a few other things. It is sooooooooooooo hard to give into this unhealthy eating, but sometimes I find letting her eat what so really wants to gets her to eat more of some better things... Good luck!