All feeding practices that put a cat at risk must be eliminated. Young , healthy cats that consume excessive amounts of fat run the risk of becoming obese.
A diet of only liver (that your cat will consume with glee) invariably leads to bone and joint disorders as a direct result of the vitamin A overdose (liver is very high in vitamin A). Extreme cases can result in fusion of the vertebrae of the spinal column.
An obese cat whose food intake is suddenly reduced runs the risk of hepatic lipidosis. Frequent changes in food cause digestive problems, including vomiting and diarrhea.