Whether you’re talking about a dog, a human, or just about any other living thing, obesity occurs when too many calories are ingested and not enough are burned off by exercise. The food a dog eats is stored as energy, and if he eats too much, the excess will be stored as fat.
There are a lot of factors that can lead to obesity in dogs, including a high-fat diet, too many table scraps, and not enough exercise. You might be giving your dog a healthy type of food, but if you give him too much, you’re not going to do him any good. Age can play a role, as can heredity, breed, and even gender.
If your dog doesn’t get enough exercise, he might become obese, even if you’re careful about how much food he gets. Older dogs, as well as dogs that have been neutered or spayed, tend to be less active and at a higher risk of gaining weight. Beagles, Shetland Sheepdogs, Cocker Spaniels, and Labrador Retrievers are a few of the breeds that tend to become overweight as they get older.1
And as odd as it may sound, dogs with overweight owners tend to become obese as well.