My brother, who started out a bit chunky but in no way fat, lost 30 lbs in 2 months when he started having issues with his gallbladder. Between time of diagnosis and then removal, there were very few foods he could keep down. He is a super health food freak so he tried to pack as much nutrition as he could in the foods he could eat. He lost a ton of weight.
Not that anyone wants to get sick or need surgery but if you have to have symptoms,heck...why not make it one that actually works in your favor??
Hang in there, find the foods you can eat and eat the healthiest version you can find of it and make sure you stay hydrated! I'm sorry you are not feeling well, hope you get through this quickly!!