Our 21 lb cat is on a diet. He swallowed a piece of string two weeks ago. During surgery to remove it the vet did liposuction. No kidding - liposuction on the cat because there was fat in the way. I thought he was joking at first. Now that I know it was done I can see the difference.

Piper gets a specific amount of food each day and seems fairly happy with that. It's not much less than he was getting anyway. We play with him in a more active way now. He isn't an active cat so it's hard to get him to get up and moving. We tie a piece of paper on a string and drag it around. Whatever we can do to get the cat moving is what we can do. My daughter lugs him to the kitchen so that he walks through the house to get back to the couch. If he's on the couch she turns on the can opener to get him to come to the kitchen.

We have Piper's sister. Same mother, apparently different father. He's a 21 lb monster that's brown and has long hair. She's a six pound petite, short black haired cat. They eat the same amount of food. He's lazy and wouldn't go outside to save his soul. She's active and always on the go. Genetics are interesting.

We got a laser pointer, and started exercising the cat with it. She is usually lazy, but when that pointer light is on the floor, she will chase it until she's panting. She's lost weight that way.

You could also switch to a high protein food. There are several "diet" cat foods on the market.

Take the cat to the vet to perform an evaluation and the correct diet, it´s not just a matter of putting him into diet food "just because", weight loosing diets have to be under medical suprevision.

This is for Robin, we also have a 20# male and his sister.
Same mother, obviously different daddies. He's a tri-colored male and very tall and long. His sister is marked like a siamese and very petite. Acts like a siamese with the same meow. Indeed, genetics..what a trip.
Patti

Just took my over weight (but only by a few lbs) to the vet for a check up. Vet said to cut down her cat food b/c it's made mostly of fillers, and start giving her more protein... eggs, chicken, hamburger, etc. He also suggested that I let her outside to hunt a bit. He's a country vet, and we live in the boonies, so she does go outside a bit, but is not real fond of the cold weather.
But his biggest suggestion was to cut down on "cat" food, and replace it w/ protein.

The most important thing when dealing with cats is never to deprive them of food. If a housecat goes too long without eating, their liver can permanently shut down. Cat's livers are not good at processing stored fat, so it builds up and causes malfunction in the liver when their food supply runs low. This condition is called Hepatic Lipodosis and is fatal if untreated. A cat with this problem will be hungry but will refuse to eat, and must be force-fed for at least 10 days to recover. Obese cats are especially at risk for this because of the extra fat they carry, so it's most important for them to have a ready source of both food and water always available. The only safe ways to help a cat lose weight are to slowly supplement their diet with fresh meats (since they are pure carnivores), and to encourage exercise. For cats with problems exercising (due to arthritis or what have you), I have even heard of liposuction being performed, but this is surgery and carries risks.

Oh my goodness! How funny genetics can be is right! My 20 lb long haired Siamese (!!) marked cat is daughter to a teeny tiny gray striped tabby and has skinny black siblings. Instead of the expected Siamese "MEER-OW", very loud, she has a teeny tiny voice like her mama does. LOL Ya gotta love 'em.

Here's what I see happening at my place:

Overweight me is on exercise program, so I walk. Overweight dog, same thing. Dog walks with human for exercise. Normal weight duck follows behind. Overweight cat will gladly follow.
We have sidewalks here now... So, can you see this quad walking down the sidewalk together...? LOL The local tv station would be out here doing a 2 minute segment about "What a Great State" this is! Around here they call it "Frontier Humor". ;-)

Seriously, though. I've learned that extra stored fat is actually treated as a "poison" by the system and can do considerable damage to human and animal or duck alike.

I have a 20+lb Persian alpha male with 4 other cats. He is fairly active and is on a special diet for the Vet. The problem is that he extorts food from the other cats if I don't watch him closely. If I put out dry food he stands over it and decides who gets what and how much. I'm looking for an appetite suppressant for cats or a fat farm for cats.