People with fat cats may want to think about investing in some pet toys and playing with their animal, as this will help them lose weight.
Dr Pete Wedderburn, a vet journalist, said that exercise is important to pet weight loss and as you cannot take a cat for a walk, playing is a good alternative.
"Obviously you don't want to take a cat for a walk, but the kind of thing you can do would be to increase the amount of time you spend playing with your cat," he said.
"Some people don't spend any time playing with their cat - but they should do. You can use a toy, a laser pointer or whatever."
The vet added, however, that the biggest issue with pets being overweight is through overfeeding them pet food or giving them the wrong type of food.
He said that diet is very important as being overweight is bad for the animal's health. Obesity, he said, is down to people not knowing how to feed their pets properly.