I dont why bro i just cant hold food in it comes right up. It was hard to gain all the wieght but to do so i had to stop working out. If i lifted and did cardio a few times a week then would liquid foods do the trick.
When you say it comes right up, I am assuming you mean you puke after you eat, correct? I think I know what you're talking about as I've had a similar issue over the past year or so. I'm no doctor, but having dealt with a similar issue, I've done tons of research on it and seen the doctor about it as well.
In my personal experience with it, it just started out of no where. I couldn't connect it with anything physically or mentally. I just started having an issue with throwing up at random times. I wasn't sick, didn't feel sick. Just gagged and threw up at random. It had a huge impact on my appetite. At it's worst, I could go days without eating. I actually had to start drinking "ensure plus" because solid food would simply come back up, but I could hold liquid down.
After seeing a doctor about it, he assumed I had acid reflux and prescribed Nexium. In my case, this didn't help at all. But it might help you. The way he explained it to me, your stomach acids are coming up into your esophagus and your body reacts by throwing up. My dad has the exact same problem and the Nexium did help him. It stopped him from throwing up after eating almost immediately. You may want to give it a try. Throwing up can do a lot of damage to your insides and you can end up with a bigger problem if you dont get it treated. You can tear a hole in your esophagus.
In my case, after the Nexium didn't help at all, I finally found something that does work. Musinex. I take it twice a day and i no longer puke and am able to eat just fine now. I had a lot of mucus building up in the back of my throat which was making me gag and throw up, and the stress it caused was impacting my appetite.
Either way, you should definitely see a doctor. You should be able to eat and hold down food. If you can't, something is wrong and you need to get checked out.
Also, there is a pill called Periactin that is a great appetite stimulant. They prescribe it to a lot of kids that take Adderall and it's pretty easy to find and cheap. It works great for increasing appetite. It takes a few days to kick in, but if you take it every day, you'll find yourself getting up in the middle of the night murdering the fridge!
Good luck!