Most cat formulas fit into one of several categories. Choose the type that best suits the needs of your pet, and be sure to check for the AAFCO label no matter what type you buy. This will ensure that the food meets the standards of the American Association of Feed Control Officials, an organization that sets standards for nutrition, testing, and labeling of all domestic animal foods.

• Kitten formulas (also called growth formulas) are foods made for kittens. They contain a higher percentage of protein and fat and a higher mineral content to meet the needs of kittens' growing bodies. Kitten foods are generally recommended for the first year of a cat's life, and also for pregnant or lactating queens.
• Adult formulas (also called maintenance or conditioning diets) contain lower levels of protein, fat, and minerals than do kitten foods. This helps prevent obesity and urinary tract problems.
• Light formulas (sometimes labeled less active or lite cat foods) contain less fat and protein than adult cat foods. Some light foods have more fiber than adult formulas, so your chubby cat will still feel full after a meal. Although the fat and protein levels of light foods vary quite a bit from one brand to another, these foods are generally suitable for adult cats only.
• Senior formulas are relative newcomers to the market. Many manufacturers used to recommend feeding light diets to older cats because slightly lower protein levels are believed to be beneficial to cats that may have decreased kidney function. However, these foods did not always provide adequate calories for older cats that weren't necessarily overweight. Reducing the protein without restricting fat content resulted in formulas more appropriate for senior cats, although the jury is still out on whether cats who show no evidence of kidney problems really need a diet that's lower in protein.