Healthy Weight for Your Cat

WebMD veterinary experts answer commonly asked questions about cats' weight, diet, exercise, and more.

By Sandy Eckstein
WebMD Pet Health Feature

Reviewed by Audrey Cook, BVM&S

According to a 2008 study by the Association for Pet Obesity Prevention, 57% of U.S. cats are overweight or obese. That's 51 million fat cats. So how can you tell if your tabby is tubby? And what can you do to help your plus-sized Persian shave off a few pounds? We asked Tony Buffington, a nationally known expert in feline health and nutrition, who has researched how to keep indoor cats happy and healthy, for some advice.

Q: How can I tell if my cat is too fat?

A: You do a body condition score. Look down at your cat. You should be able to see a waist when you look down on it from the top, or when you run your hands from its ribs to its hips. Run your hand along its abdomen from its ribs to its pelvis and it should be indented.

If you put your hands on the side of its chest, you should be able to feel its ribs without a thick layer of fat over them. There are charts that show this. You can find them online - all the pet food sites have body condition scoring charts. Or ask at your veterinarian's office and they can show you the chart and help you evaluate where your cat falls.

Q: Are some breeds more prone to weight gain?

A: A couple of studies have looked at this, and surprisingly, they found that mixed breed cats are about twice as likely to be overweight than purebred cats.

Q: Why should I care if my cat is fat? He looks happy to me.

A: It depends on why your cat is overweight. If he's overweight because he eats too much, or you feed him too much, then there are the common beliefs that obesity can lead to shorter life spans, diabetes, or joint and skin problems.

But often, cats are overweight because of environmental causes. So first we need to figure out why your cat is overweight. Is he not moving enough because he's terrified in your house? Do the dog or the kids attack him every time he comes out of hiding? Or, is he bored because there's nothing to do in the house so he just sits around and eats? If that's the case, then changing his diet or the amount of food he eats won't help his weight problem. He's not a happy fat cat. He's just fat. So the issue then is making your home a happier place for your cat. If he's happier and more active, then he'll probably lose weight.

That's why, when I work with fat cats, I look at the environment as well as the food intake.

Q: Will spaying or neutering a cat make it gain weight?

A: Studies that have been done on this topic suggest that spaying or neutering a cat can cause a change in the cat's body weight of zero to 25%. Removal of the hormones will change its metabolism a little bit and it will change its activity level a little bit. So my advice to owners is to be careful and pay attention. This is the time to keep checking that body condition score we previously talked about. Or, if you have a scale, weigh your cat regularly. And if he starts gaining weight, we might need to cut back his food intake, or switch his diet.

Q: What kind of diet should my cat be on to lose weight?

A: If we want a cat to lose weight, we have to do two things. We have to think about what we feed him and we have to figure out how to make him more active. One easy way to do both is to feed out of a foraging device. These are small plastic containers with holes that we put the cat's food in. The cat then has to play with the device to get the food to fall out. Cats will work for food, which a lot of owners don't realize.

But remember, we never want to change an animal's diet without asking their permission. And the way we ask permission is offer the new food or new feeding device alongside the old dish or food.

Owners also need to know that the food intake recommendations on pet food packaging labels are generally well above what most pets need to consume. Those recommendations were developed for intact, active animals, while most of the animals I see are sedentary, spayed or neutered pets.

Q: I tried putting my cat on a diet and he howled for days. Are some cats just too old or set in their ways to change?

A: When trying to change a pet's food, never take away the old food completely. For many cats, the old dish and food are actually a safety signal. Cats like familiarity. They don't like a lot of change. So if you need to offer a new food, offer it alongside the old food. Give your cat a choice. Usually, when it's done that way, the cat will at least try the other food eventually, and if he likes it, he'll eat it.

Q: My cat is an indoor only cat. Can he get enough exercise inside to lose weight?

A: Of course he can get enough exercise if you're providing him an enriched environment. So give your cat climbing structures because cats love to be elevated. They need windows they can look out. Use foraging balls to encourage exercise. And they need to feel comfortable enough to come out. If they're afraid of half the things in your house, they won't come out to exercise.

And that includes people. Remember, you should never use punishment as a teaching tool. If you slap a cat, he thinks you're trying to kill him. He can become immobilized with fear. But cats respond marvelously to praise and treats.

Q: Does my cat need to see a vet before starting an exercise plan or a diet?

A: It's a good idea just to be sure there's not something else going on. There are probably a dozen different causes of obesity in cats, ranging from overeating and overfeeding to inadequate activity, seasonal obesity, and even some drugs and diseases can cause weight gain.

I'd also like the vet to do an environmental history to make sure the cat isn't fat just because it's afraid to move - the dog is bothering it or the kids are pulling its tail every time it comes out. That's actually fairly common. Owners need to know if their cat hides a lot, that's not normal cat behavior. So we need to help them find a way to structure the home life so the cat is moving around and interacting with its environment.

Q: Should I cook for my cat?

A: You can, but I don't recommend it. It takes a lot of time and you have to include supplements. If you want to do this, you really should talk to your veterinarian to be sure you're doing it correctly. There are places that will sell you the supplements and then you can just add in the protein and carbohydrates, if you have the time and the interest.

Q: Are there any diet pills for cats?

A: No. They have one for dogs, but that medication is dangerous for cats.