The reasons why this happens are as follows: 1. The cat is in an unfamiliar environment, without its owner around, and is nervous and resistant to the environment. It will stop eating and lose energy; 2. The cat eats the wrong food. Gastrointestinal discomfort, there will be short-term physical discomfort and no desire to eat; 3. It may be that the cat wants to vomit the hair balls in the body, causing a loss of appetite.