Cat Food 101: What You Need to Know About Feeding Your Cat

View the Things You Didn't Know About Your Pet Slideshow Pictures

Cat Food 101: What You Need to Know About Feeding Your Cat

We answer frequently asked questions from cat owners about cat food and feeding.

By Annie Stuart
WebMD Pet Health Feature

Reviewed by Mark J. Stickney, DVM

You want to keep your feline healthy and frisky and you know that good nutrition is essential. But what makes a healthy cat food? What type of cat food is best for your pet? And do you need to know anything special about storing it? Here's an introduction to cat food, where we answer frequently asked questions from cat owners about cat food and feeding.

What is cat food made of?

In general, cat food consists of water, proteins, fats, carbohydrates, vitamins, and minerals. But how close your cat's diet comes to that of its feral cousins depends on what formula the cat food manufacturer uses.

Proteins are the basic building blocks for cells, tissues, and organs. They can be either animal-based or plant-based, and either type may show up in cat food. Soy, vegetables, and cereals are examples of plant-based proteins. Chicken, lamb, turkey, and fish are examples of animal-based proteins. In addition, cat food often contains byproducts of animals or plants, the parts that people don't normally eat.

Cats are meat eaters. That means they require two to three times the protein that omnivores, such as dogs or humans, do. As strict carnivores, they rely mainly on nutrients found in animals -- high protein, moderate fat, and minimal carbohydrates -- to meet their nutritional needs. For one thing, cats' bodies are adapted for metabolizing animal protein and fats. In addition, animal-based proteins also contain complete amino acids, such as taurine, arginine, cysteine, and methionine. These are essential for cats whose bodies don't synthesize them in adequate amounts.

Although carbohydrates provide energy, cats use them less efficiently as an energy source. Their bodies are designed for a steady release of glucose from protein. The most concentrated form of energy, fats in cat food help with absorption of fat-soluble vitamins and provide essential fatty acids that a cat also can't synthesize well. These include omega-6 and omega-3 fatty acids. For good nutrition, cats also need vitamins, such as A, B, D, E, and K, as well as minerals, such as calcium and phosphorus.

Which is better, dry cat food or canned?

Controversy surrounds cat nutrition, just as it does human nutrition. And few topics garner more attention than the canned vs. dry food debate. Jennifer Larsen, DVM, PhD, is a nutritional consultant and assistant professor of clinical nutrition at the Veterinary Medical Teaching Hospital at the University of California, Davis. She says that a high-quality brand of cat food -- either wet or dry -- can be nutritionally complete. But she also tells WebMD, “Some cats benefit from the higher moisture content of wet food, which makes their urine more dilute. But most cats do fine on dry. It's an issue of personal preference.”

Other veterinarians draw a line in the sand on this subject. Among them is Lisa A. Pierson, DVM, a practicing veterinarian in Lomita, Calif. Pierson has three concerns about dry food -- moisture, carbohydrates, and type of protein. “By and large, the canned food is going to have more meat, more protein from animals,” Pierson says. “In the dry food, a lot is often coming from plants.”

Mindy Bough, CVT, says you should avoid foods with very high percentages of carbohydrates. Bough is senior director of client services for the Midwest Office of the American Society for the Prevention of Cruelty to Animals (ASPCA). She tells WebMD that foods with high percentages of carbohydrates may lack necessary fats and proteins.

According to Pierson, no more than 10% of the calories in a cat's diet should come from carbohydrates. She also believes the high-starch, energy-dense nature of dry foods may contribute to obesity in cats. “The worst culprit is free feeding dry food,” Pierson says. “It's like setting out a bowl of Doritos for your child to chomp on all day.”

And, no surprise here: dry cat foods are a little dry. Pierson tells WebMD that dry cat foods typically contain between 5% and 10% water, while canned foods are about 78% water. Water is a critical nutrient that helps with digestion, circulation, and other bodily processes. So why not just keep the water bowl filled up? Although there isn't 100% agreement on this, some studies show that cats are less sensitive to thirst and dehydration. Cats fed a diet of dry food may ultimately consume about half the water that cats eating wet food do. This can contribute to concentration of minerals in urine leading to serious problems with the urinary tract.

What ingredients should I look for in my cat's food?

“Animals require nutrients, not ingredients,” Larsen says. It's important to keep in mind that ingredients will have different levels of nutrients. How well those nutrients can be absorbed may also differ, she says. “Unfortunately, this makes it difficult to judge quality by the label, especially because the way a diet is constructed is proprietary information.”

You can glean some information from the label, but because ingredients are listed in descending order by weight. “Out of all of the important nutrients, protein should top the list,” says Bough.

Pierson feeds the cats in her care a grain-free, meat-based diet. “Many high-quality foods have ingredients like carrots, blueberries, peas, and apples to appeal to people, although those are not necessary ingredients in cat food,” she says. However, in small amounts, they are not harmful.

So how can you make cat food comparisons or evaluate cat food brands? Although it's a bit like “pulling teeth,” Pierson says, you can ask food manufacturers the percentages of calories that come from different types of nutrients. Or there are web sites, such as “Janet & Binky's Cat Food Nutritional Information Page,” that provide information about the nutritional content of cat food.

“The manufacturer's reputation and experience are really important,” Larsen says. “And, I strongly prefer foods that have been through AAFCO feeding tests.” The Association of American Feed Control Officials or AAFCO is a group of state and federal officials who regulate pet food to ensure that nutrients exist in correct amounts and ratios.

You can look for the AAFCO seal of approval on your cat's food label. But it's important to keep in mind that the feeding trials approved by AAFCO leave much room for improvement, Pierson tells WebMD. In particular, Pierson criticizes the size, parameters, and length of these trials.

What is natural or “holistic” cat food? Is it worth the extra expense?

Does a cat food have to be natural or “holistic” to be a healthy cat food? The USDA says a product can carry a “natural” claim if it has been minimally processed and contains no:

  • artificial flavor
  • coloring ingredients
  • chemical preservatives
  • other artificial or synthetic ingredients

Are there certain chemicals and preservatives you should avoid in your cat's food? Not necessarily. Preservatives in pet food help to slow the breakdown of food and to maintain its nutritional value longer. “Preservatives such as ethoxyquin, BHT, and BHA are important antioxidants in pet food,” Bough says. “These products have been used in pet food for more than 25 years, and when used in specified amounts, have not been found to cause harm to pets. In addition, there are natural preservatives, such as Vitamin E, that help preserve pet food.”

No regulatory definition exists for “holistic” cat food. “It's used as a marketing term,” Larsen says, “and every company has a different definition for it, so it's not particularly useful.”

If you're looking into cat foods with these kinds of claims, a talk with your veterinarian may be useful, Bough says. It's helpful to keep in mind that high-quality, more expensive brands -- whether natural or not -- are sometimes a better deal in the long run. That's because, with more nutrients readily absorbed, she says, pets may not have to eat as much food per serving.

How much should I feed my cat and how many times a day?

Larsen recommends feeding cats one or two times a day. “Two times is better than one,” she says, “because you can otherwise get some undesirable begging.” With obesity affecting one in five cats in industrialized countries, many people also wonder how much to feed.

“It's best for owners to learn how to evaluate their own cats,” Larsen says. That's because cats are individuals just like people. Their energy requirements will vary depending upon climate and activity levels, among other things. The main problem is people are feeding palatable, energy-dense foods in uncontrolled amounts. “They feed the bowl, not the cat.”

Pierson agrees and says to keep it simple. Too fat? Feed less. Too thin? Feed more, as long as you're feeding a high-quality diet.

How do I change my cat's diet when I want to switch types of cat food?

If you decide to change your cat's diet, make the transition to the new food slowly, over a period of five to seven days, Bough suggests. “Begin by adding 25% new food to your pet's 75% old food. Then gradually increase amounts of the new food until you've made the complete transition. A slow transition allows your cat time to adjust to a new food and also decreases the chances of digestive upset.

How do I store cat food?

Some ingredients, such as fish oils, are fragile, Larsen says. For this reason, it's better to buy only enough food to last four to six weeks. Don't store food in a hot garage or carry it around in a car. To prevent spoilage from mold, store dry food in the bag or other container in a cool, dry place, Bough says. Refrigerate unused wet cat food for no more than 24 to 48 hours.


Zoran DL. Journal of the American Veterinary Medical Association, Dec. 1, 2002; vol 221, no 11: pp 1559-1567.

ASPCA: “Nutrition Library.”

Jennifer Larsen, DVM, PhD, nutritional consultant and assistant professor of clinical nutrition, William R. Pritchard Veterinary Medical Teaching Hospital, UC, Davis.

Lisa Pierson, DVM, Lomita, California.

Mindy Bough, senior director of client services for the ASPCA Midwest Office.

Subscribe to MedicineNet's General Health Newsletter

By clicking Submit, I agree to the MedicineNet's Terms & Conditions & Privacy Policy and understand that I may opt out of MedicineNet's subscriptions at any time.

Reviewed on 12/3/2009 11:29:41 AM

Health Solutions From Our Sponsors