Take your cat into the vet, you need to rule out any physical problems

Also what foods do you feed, ANYTHING in a supermarket is crap, made from cancerous meats,shelter animals,roadkill, and is quite litterly toxic to humans.

I would try Innova EVO, or Orijen or Ziwi peak. Wellnes for me was good/but one of my cats threw up on it.

Once of course the vet rules out a physical issue- Also DO NOT buy food from your vet, this is a terrible idea because most vets haven't a clue on feline nutrition, they go by what the massive companies want, because that's who funds their education in vet school.

Years back, I had a trio of cats. I got them all as kittens within days apart. Two were littermates (Pumpkin and Cecil)from a shelter, followed by Princess who was a beautiful little street urchin someone rescued and gave to me. Pumpkin and Cecil were regurgitators for their entire lives...and which ever one barfed, the other would eat the barf. Lovely. Princess never barfed except for an occasional hairball. They ate the same diet. I remember the vet telling me to feed them seperately (not practical in a small apartment)because that would slow down their eating if they didn't feel threatened by the other cats. I tried it, it didn't work. I also gave them Petromalt regularly to help with hairballs.

I think on another thread on this subject someone mentioned that it may be something physiological that is peculiar to some cats and not others. The experience with my cats would tend to validate that theory.
But I agree with Runsawalkin...feed them high quality canned food. And Mazer is right as well...get them checked out at the vet just in case.

Do they have hair balls?.

I had a cat that would eat heartily, then back away from her bowl and throw everything up. After a visit to the vet, it was determined that she a) wasn't chewing anything and b) had a smaller than "normal" opening into her stomach. She ate high quality ground food (sometimes mixed with water to make it thinner) for the rest of her very long life. No more throwing up her dinner. BUT the key was taking her to the vet for the diagnosis.

There is a huge difference between regurgitation and vomiting in terms of the type of problems that can cause each one.

Regurgitation always indicates a problem with the esophagus. That could be anything from strictures, inflammation, neuromuscular disorder such as myasthenia gravis, foreign body, etc. Regurgitation can occur any time after eating, just like vomiting. It does NOT have any abdominal effort- no stomach contractions- and there is no warning before regurgitation. They just sit there and suddenly BLECK you've got a pile of stuff in front of the cat. It's like they just burped up the food or whatever comes up.

Vomiting can have about a million and one different causes, but it is NOT an esophageal problem. Vomiting is characterized by abdominal retching prior to the spewage- you KNOW it's coming! There is nausea as well, so some animals drool or lick their lips prior to vomiting.

It is important for the vet to know whether or not the cat is vomiting or regurgitating so you don't spend all your money chasing down the wrong problem.

If the cat is regurgitating, it is usually difficult for a general practitioner to get a diagnosis. Sometimes it is because the cat is eating too fast, and adjusting how you feed the cat may solve the problem. However if there is a medical cause for regurgitation, you will probably need specific tests such as endoscopy to look into the esophagus, or fluoroscopy to check for proper emptying of the esophagus, or specific neuromuscular tests. These are not usually available to the general practitioner, so you may need referral to a specialist.

Vomiting can be due to a problem in the GI tract (foreign body, mass, IBD, cancer, parasites) or a problem not within the GI tract such as an endocrine disorder (hyperthyroidism is common in older cats), or an organ problem (liver or kidney disease for example). Sometimes bloodwork can detect organ problems, but primary GI problems are usually found with X-rays or surgical biopsy.

Since the cat is losing weight, it is very important to follow this up with the vet. Make sure s/he understands if your cat is vomiting or regurgitating so you don't waste time or money doing unnecessary tests. You may have luck with symptomatic treatment for either problem as well. Just be prepared to keep following through with the vet if one type of treatment doesn't work. Good luck with everything.