If It Is Not Fried or Sugared or Cheesy....

http://www.autism-diet.com/

You don't say much about his behavior just his eating habits. If you look at the page about the Autisim diet you will see that all that dairy and gluten foods will cause him to have meltdowns. My granddaughter is Autistic and my daughter found out that Autistic children will crave yorgert and it makes them violent. If he really is Autistic you need to radically change his diet and start him on therapy. Contact Headstart for a real diagnosis and some ideas. The Easter Seal organization has helpful advice as does autisimspeaks.org

Try not to buy or give in with the junk food. Your child won't starve in a few days. Have all the healthy stuff on hand and offer it often. Pizza isn't bad. Mac and cheese too. Lots of kids avoid veggies. I'd suggest a good multivitamin and possible meal shakes that taste pretty much like chocolate milk. As your child grows he will broaden his horizons. I wouldn't over worry it.

If you would like links to some good vitamins and meal shakes send me a msg.

Was your son misdiagnosed with Autism Spectrum Disorder? I can tell you that this doesn't just go away. My nephew has it and your son sounds similar just by his eating habits.
Stop buying junk food so it is not there to give. Also check with a therapist about his disorder. Kids with sensory issues will not eat certain foods and I remember my nephew only wanting sweets and foods that become sugar in your system and refusing others because of the texture. Please find a good ped and/or doctors that will listen to you so he can get proper diagnoses and/or find out what’s going on.
Believe me if a child is hungry they will eat what they are given. He will not starve to death or become malnourished within a few days. If you only offer healthy foods he will eventually eat them. He is still very young and some kids just get picky around this age.

added: I know nothing about autism and would check with the doctor first my answers only regarding what I did with my daughter
Sounds like M. when I was little and my niece. Honestly its not a choice for my daughter if she eats her vegtables and fruits its a must. I'm not insanely strict some days she has cake for breakfast or today she took peporoni cheese and crackers to school for her one snack, but most of the time its fruit and veggies. When she was little I convinced her she was actually shrinking if she didnt eat good foods and then she J. developed a taste for them. Also I would tell her the broccli were trees and she was a heravioure dino and she had to eat them. Also she learned from M...id eat salad and she natarually wanted to eat anything i was so even though I could tell at first she ate it J. because it was mine eventually she began to love it. If I have junk in the house obviously shes going to beg for it, so the easy thing to do is get rid of all of the junk and eventually he'll get hungry enough to eat the healthy stuff. Make it fancy at first give him toothpicks with umbrellas on the end to pick the fruit up with...cut the veggies and put them around a wine glass with ranch inside and make him feel like a king for eating it. IDK I always made it a must that she eat her veggies and fruits..I never got the whole I'd rather them eat something approach...they wont starve themselves. I can tell you that the amt of times my daughter ate chicken nuggets at home I can count on one hand...not to say she doesnt love mcdonalds if i let her go...but she wouldnt know its A. option for home...
I do have to say since xmas weve had wayyy to much cnady and she'll scarf down 3 plates of veggies J. to get the option to eat candy and then tis constant begging...this week bugs are gonna come and eat all of the candy again...ooops I shouldve cleaned better=)

Well you are definitely encouraging this. Since 3 year olds cannot go to the store, they cannot eat donuts and chicken nuggets and macaroni and cheese unless you feed it to him. I would get all the junk out of the house and only offer him foods that are healthy. We fed my son exactly what we were eating (minus honey and choking hazards) from the point he started eating solid foods. When he saw us eating broccoli and salmon and artichokes, he wanted to try them. Of course he has likes and dislikes - everyone does. But if you facilitate him eating highly processed easily palatable foods, he will never learn to eat well.

There is good evidence that children need to try a new food at least 10-16 times before they will reliably accept it. That is WAY more times than most parents offer a new food. There is also good evidence that hiding vegetables in their food does NOT increase their acceptance of vegetables.

Other tidbits - rewarding a child for eating a new food increases their liking for the reward and decreases their liking for the food they were rewarded for trying. Children become lifelong adventurous (or picky) eaters as toddlers (all anecdotal 'my kid turned out fine' stories aside) - what you feed them now counts. What is 'child friendly' is culturally - not biologically - determined.

Good luck - what you feed him now really does matter.

There is no evidence that a restrictive diet is beneficial for children with autism. While I understand wanting very much for diet to help - the research says it does not. http://www.mayoclinic.com/health/autism-treatment/AN01519

Speaking and potty training do not negate a diagnosis of autism. Regardless of his diagnosis, I highly recommend taking your son to see a nutritionist and A. occupational therapist. The pediatrician is not the person who has the expertise regarding your current concerns. The nutritionist can help you assess whether or not your son is getting proper nutrition, and develop a meal plan to meet his needs. The OT can help your son diversify his diet by helping with the texture and other issues. Also, OT can help with fine motor skills, which will help your son with using utensils (my 7 yr old still prefers to use his fingers because the effort it takes him to use utensils). Good luck!

I have a friend whose son is currently in the diagnosis stage for autism. He's 6 or 7. He NEVER ate. It didn't matter how long junk food was withheld, or how many times he had to option to eat better food, he refused to eat. He did starve, in a way.

While you think the diagnosis was wrong or he "outgrew" it, it would be beneficial for both you and your son to get him to a doctor that specializes in autism to identify the real issue. It could be sensory, it could be something else. It might not have anything to do with his autism diagnosis, but it might - and if it does, I don't think you can fix this on your own. And while 99.99% of kids will eventually eat what's placed in front of them if they're hungry enough, it doesn't mean yours will.

Get him medical attention before this goes on much longer.

Well, I can tell you that it is not unusual and not just related to some disorder. My had his first pizza at 10 yrs old. Because pizza is made with tomato sauce! If we made pizza at home, then he would eat it if only made with cheese. And pasta could not have tomato sauce. If I made baked spaghetti or other, I had to keep plain on the side for him. He has grown out of most of his food things--like only chicken nuggets. Our ped also was not too concerned. You might be able to get him to eat more veggies by having something of a healthy sugary snack for after he at least tries something. If he gets that snack fist he won' t bother and is in charge. I usually bought granola bars with lower sugar or something I made myself that I could control the sugar.
Oh, and my son LOVED pumpkin bread. You can sneak in quite a few goodies in bread recipes. I once added pureed cauliflower-which he still does not like-to banana bread. Never noticed. I even added a baby food prunes or carrots. I also added a half cup of chocolate chips for a little sweetness.

Some things to make eating fruit more appealing -- leave apples, bananas, and oranges out in a bowl on the table every day. The food we see is the food we crave! To make veggies more appealing -- ask your kid to help cut up veggies for dinner. Do the big cutting so he has just thin slices to cut up with a knife. (It's OK to make his cutting board veggies germy as he wants -- they don't actually have to make it into the dinner). Also see if there is any gardening you can do -- it's almost time for planting snap peas which are great fun to pick right off the plant, and they can be grown in a small pot with a trellis. Carrots are super easy to plant from seed after the last spring frost. If you don't have a yard, you might be surprised how easy it is to grow alfalfa sprouts or mung bean sprouts -- just put seeds between wet paper towels and wait overnight or so. Bean sprouts are super yummy when fresh! If you want practice with utensils, you can also try children's chopsticks (we have these really great ones with dinosaurs on the tops), or even let him try to eat with just one chopstick. The point is, if you do gardening, let him do the planting, if you do cutting up of veggies, let him do the cutting. Also, DO get rid of the sweets in the house. He sure does know that he can have sweeter stuff if he doesn't eat his dinner. Aim for NO dessert, but of course he will have some when visiting with grandparents, etc. Also, when you make a meal, try to make at least 2 piles of food on his plate - one he loves, and one he hasn't tried or doesn't like. Give a small portion of the one he likes -- if he wants more, he has to try the other pile. Also don't forget the power of psychology -- one trick I did with my daughter who doesn't like much meat was to pretend to try to stab the small chicken pieces with a fork, but fail miserably. When I asked for help, she would stab the chicken and put it in her mouth without thinking!