Indigestion is frequently observed in cats, and a common problem of home prepared diets, which often discourages care givers from maintaining their cats on a fresh food regiment. That said, commercial foods can cause indigestion as well, but the reason it occurs more commonly with home made diets is a lack of understanding of feline physiology and the nature of the cat as true carnivore by the person formulating the meals.
Being an obligate or true carnivore does not merely mean that the cat must eat meat to survive, but also that she should not ingest plant matter; and if so, only in small quantities and well processed, eg. digested or cooked, because she lacks the ability to produce enzymes necessary to break down these plant driven foods. Wild cats are rarely observed eating plant foods. Lions and Cheetahs will occasionally eat gourds, probably as a source of water. In times of extreme famine African wild cats (Felis Silvestris Libyca) have been observed eating olives, and only the Margay (Leopardus wiedi), a small spotted cat of South America, is said to include fruit in her diet. Many domestic cats also show a fancy for some fruit, especially cantaloupe. Such foods are best fed as treats and not combined with other foods, especially meat, to prevent indigestion.
The cat is best adapted to ingest small, whole, raw prey. Anything that differs from this meal-plan can present a challenge to digest. If food is not digested properly, it can ferment in the intestine, producing hydrogen and carbon dioxide. Fermentation can also occur in the stomach if foods are combined and eaten in one meal, of which one ingredient is highly digestible and the other is not; or both may be highly digestible, but differ in time it takes to digest them.
Symptoms of indigestion are: passing gas, or burping of an offensive gas shortly after ingestion of the meal; the food may be regurgitated up to 12 hours later seemingly undigested, but with an offensive cheese-like odour.
The common mistake made in home preparing meals for cats which cause indigestion is the expectation that foods good for humans are good for cats as well, resulting in very uncomfortable consequences for the cat with none of the well meant benefits. Indigestion is not to be taken lightly!

Sensitivity to indigestion varies greatly amongst cats. Many cats are completely unaffected by any of the above mentioned points, but equally many are.
The symptoms of indigestion may also have a medical condition as the underlying cause, such as an intestinal obstruction, peptic ulcer, or a disorder of the pancreas, liver, or gallbladder, and a veterinarian should be consulted in addition to re-evaluating the cat's diet. A possible allergy to a certain food should also be taken in consideration.