Why am I vomiting after eating?

There are several possibilities. If he likes the cat food too much, he may be eating more than his stomach can hold, and he must then vomit to relieve the pressure. It is possible that the cat food has been adulterated, particularly if some of its components were made in China. Some cats simply have a chronic irritation of the stomach that causes them to throw up frequently; this last can be treated with an anti-inflammatory. In any event, if the vomiting does not seem to be related to a change in cat food, you should certainly see your vet, as it could be something serious but treatable.