The holidays are over, and we’re all feeling the weight gain. Even our pets. January aside, the Centers for Disease Control has found that obesity in all of us has skyrocketed over the past 20 years.

Studies have shown that our animal companions are not immune to this trend. Anyone who has gone to a vet and stood by mutely watching as their dog or cat was weighed knows this is true. We’re overweight as a population, and our pets are too. In fact, according to the American Veterinary Medical Association, obesity is reported to be the most common nutritional disorder in dogs, with an estimated prevalence of nearly 25 percent.

Weight charts have been created showing “ideal” weights for pets. These “shape” charts show dogs and cats from two angles: a side view and a bird’s eye view. If your pet looks more like a pear, or frankly, any fruit at all, he or she is probably overweight.

So what can we do? First of all, controlling the weight of a dog is very different from controlling the weight of a cat. While humans may identify with one or the other, in point of fact, we gain weight like dogs, but lose weight like cats.

Like people, dogs are true omnivores. They can eat anything. And they often do. For them, weight loss is achieved the old-fashioned way: consume fewer calories and increase exercise. It’s essentially the Weight Watchers approach.

Not so easy though. Most dog food is very palatable, meaning it’s high in calories and fat. And “light” foods aren’t a lot better. If your dog is really overweight, talk to your vet because there are about a dozen “prescription” foods for weight loss. These shouldn’t be used permanently and I’ve had many a client whose dog has been on a prescription diet for years, hasn’t lost any weight, but stays on the “diet” nonetheless. Not a good idea. While nutritionally complete, these foods are not intended to be long-term diets. Rather, they are designed to get the weight off usually within six months to a year. Then get the pet on a “maintenance” or light diet to keep it off.

It takes very little food to plump up your dog – especially our sedentary city types, in spite of some rigorous play at Lincoln Park. It’s all about limiting those calories. We’ve all heard it – fill those food bowls a little less and feed twice a day. And remember to watch the snacks. Those between-meal treats and training rewards are like little candy bars in terms of fat and calories. And table food can put the weight on quickly. So break those treats in half or, better yet, grab an apple or some vegetables.

Along with cutting calories, exercise is key. Feed a proper diet and add an additional walk a day (probably not a bad idea for our end of the leash either), and you should start to see results.

One last word of hope: latest studies show that dogs may metabolize fats differently than people. Like us, there appear to be "good fats" and "bad fats," but these may behave differently in dogs. We’re not sure what all of this means yet, but many pet food companies are working rigorously to develop new, better weight loss diets for our overweight companions.

Cats, on the other hand, are not dogs. They are strict carnivores, rarely eat indiscriminately, and need very little food to put on weight. If dogs lose weight on Weight Watchers, cats do better on the Atkins or South Beach Diets. Twenty years ago, we advocated the same low calorie diets for cats we were using for dogs. More recently, it seems that restricting carbohydrates is the best way to go for cats. Foods like Hill’s Prescription Diet M/D or Purina’s Prescription Diet OM, among others, work like our own low-carb diets and may be most effective for cats.

Cats fed free-choice dry food are much more likely to gain weight than those who eat two meals a day. And use canned food – it is generally better for cats than dry food.

A note of caution: Cats have the strictest nutritional needs of any mammal. If they don’t get precise levels of certain amino acids, the consequences can be fatal. So make sure you use a high-quality cat food that provides everything your cat needs.

Again, exercise is key. This is not as easily accomplished as with dogs, since most of our cats live indoors where they are healthier and safer. But regular play sessions with your cat can help him shed weight. Try a laser light toy; if nothing else, it gets him off the couch.

Now, there are a few – and only a few – medical reasons your pet may be inexplicably gaining weight. With dogs, it may be a thyroid or other metabolic disorder. Usually, there are other signs that go along with these, such as chronic skin rashes or lethargy, so discuss your concerns with your vet. For cats, very few medical disorders lead to weight gain. In fact, most cats lose weight when they’re sick, not the other way around.

Like people, weight loss for either species is hard. And dogs and cats can’t join a gym. But the benefits of slimming down are tangible. Losing weight may help with – or even eliminate – lameness, prevent diabetes, clear up skin, resolve breathing problems and generally lead to a healthier, happier animal.

So why not make it part of our new year’s resolutions to be healthier, eat better and exercise more … with our pets? At least they don’t smoke.