For my son it is simply sensory. One good example is his adversion to watermelon. You may ask, like I did, what kid doesn't like watermelon. When I asked that, the therapist explained it like this... Imagine that you are oversensitive to everything and you are used to eating crunchy foods and you are used to eating liquid foods; however those foods are always either liquid or crunchy. Then you get a food (imagining this with a childs mind), and bite into it only to find out that crunchy food your were expecting just turned to liquid. Basically its a wtf moment for my son that he can not comprehend. He also has an adversion to white food. Eating mashed potatoes is a challenge for him. It was suggested to me to put food coloring in the food that he is adversed to due to the color.

Thank you all. I didnt consider it a texture issue because she will eat some things that are similar in texture to other things that she wont. I wish she could talk and tell me what she wants for dinner.....it would be so nice. Hoping that day is somewhere in our future. She hasnt liked sweets since day 1 and I never thought it might be related to ASD Thank you all for your responses.

Hi, My son is 16 yrs old now but when he was little, a he nursed till he was 3.5 yrs old and then one day he told me he was hungry! LOL! From then until now, he is the pickiest eater I know, no red, white, pick, meat (none ~ he i a veggie eater for the most part, not by choice) because is it is a texture issue. He likes one or two fruits and 4 or 5 veggies....and loves breads and sweets. (Yes, I have to watch him like a hawk ~ he could go the whole day and be happy eating only candy if you let him! But wouldn't we all! )

Lots of the time it is to do with colour or texture. Tactile reasons. The senses see or feel these foods and deem them extremely unpleasant.
For example a marshmallow 'like an alive worm in the mouth'. With foods the child once ate, hmmm, I'm a bit stumped on that, maybe the more experienced folk on here can step in and help!
Co morbid issues like sore tummy sore head or indeed like my son inflamation could out a child off their food. In autism look for a wider answer ie maybe another issue is responsible like impacted stomach etc just to be fully tuned in to all that it could be.
I hope some other answers appear.