Both Frazier and Pitcairn report dramatic improvements in the dispositions of dogs and cats who were withdrawn, irritable, or just plain mean. In addition, animals may eat less overall with a new diet. This is probably because they have been overeating their processed food in an effort to get enough essential nutrients. When they have the nutrients they need, their well-functioning bodies will not respond with increased and unnecessary appetite. The transition to the new food may be difficult.
Many animals turn up their noses at any deviation from their usual diets.
Often, their packaged food of choice contains sugar, salt, or artificial flavor, and they have become addicted to it. If you are serious about changing your pet's diet, there are ways around this, too. One is to let your pet fast. Fasting is good for most animals, but do not fast a cat with diabetes, hyperthyroidism, or cancer. Be sure to have plenty of water available.