Reasons Your Cat May Not Be Eating:
Stress - Cats can experience stress from even the simplest of changes around your home. If you recently moved residences, cats can have difficulty adjusting. Introducing a new pet into the home can also be very stressful. Other changes around the home that stress them, and possibly cause them not to eat, are moving furniture in the house, or even moving the food bowl to a new location. Cats love routines, and any changes to those routines cause stress.
Other Cats - Felines are very territorial, and may lose their appetite due to a territorial dispute with another cat. If your cat primarily lives outside, perhaps a new cat moved into his territory, thereby upsetting him. A new cat introduced into your home can upset your indoor feline friend.
Illness - If your cat seems lethargic, hides from you more than usual, and in unusual places, or goes for more than 24 hours without eating, then a trip to the veterinarian is probably in order.
Food Issues - If you have recently changed cat foods, or if the current food changed formulations, your cat could be reacting to the change in diet. If it is an outdoor cat, he may also have found food elsewhere.
There are a number of other food-related issues that could explain why your cat is not eating, and they deserve more explanation...
Cats were initially bred in Egypt, so therefore, they are instinctively desert-dwellers. Since there is little water in the desert, felines depend on getting their liquid nutrition (water) from their food. Sure, cats have been domesticated to where they will drink water from a bowl, but instinctively, they depend on getting it from their food.
Have you ever had a cat that died from kidney problems? I have, and I have learned that it was probably caused by feeding my cats a diet of dry, crunchy brown things. Sure, cats will be fine for a number of years eating dry food exclusively, but it takes a toll in the later years.
Try a variety of canned foods for your cat. They are much more easily processed by the digestive system, and they will help your cat live a longer, happier life.
For more information on feeding your cat, visit PetFoodDude.com