Soybeans mixed with boiled starch-free rice swimming in glucose gel. That is protein and the most basic of sugars. The "starch-free" rice probably isn't 100% starch free, but it's close. If you can tolerate it, the carbs would be useful.

You probably would need a few dozen multivitamin pills for dessert though. Crushing them up and adding it to the soy and sugar probably would taste kinda bad.

Still, I don't think that would be balanced enough to convince your body it wasn't starving so bulking up probably isn't going to come easy or safely.

You need protein with additional variety, and I think my concoction would probably push you over the edge into protein poisoning with a massive sugar imbalance to boot.

I started off lightly joking at first, but if you crank up the soy in your diet along with simple sugars, you can probably just add that to whatever else you can eat and be OK. Unless, of course, you have a soy allergy as well.

(Sounds like you have some serious gut issues and are incapable of breaking down most proteins and more complex sugars. I am not sure if the soy will help much or if you can get all the amino acids you need if there is a protein digestive issue going on.)