There’s no denying obesity is a major canine health issue. Obesity contributes to arthritis, heart and liver disease, diabetes, respiratory difficulties, heat stroke, some cancers and more. And somewhere between 40 and 50 percent of domestic cats and dogs in the United States are overweight, according to several estimates. As we do in our personal battles of the bulge, we turn to reduced calorie diets for help. Unfortunately, these may not be the straightforward solution they appear to be.
Earlier this year, a study of so-called light or low-calorie dog and cat foods  performed at the Cummings School of Veterinary Medicine at Tufts University revealed a confusing variation in calorie density and feeding recommendations among brands. Researchers found dry dog foods making weight management claims ranged in calorie density from 217 to 440 kilocalories per cup (kcal/cup), and that the recommended intake ranged from 0.73 to 1.47 times the dog’s resting energy requirement.
What this means is that well-meaning dog owners following manufacturer guidelines might not see promised weight loss in their chubby pups—in fact, they might see weigh gain—leading to frustration for people and ill health for dogs.
Knowing and counting calories is a priority for weight management, according to veterinary nutritionist Edward Moser, MS, VMD, DACVN, with whom we talked about the Tufts study and canine weight management. Dr. Moser is an adjunct assistant professor of nutrition at the University of Pennsylvania School of Veterinary Medicine. In addition, he serves on the National Organic Standards Board Pet Food Task Force and as consultant to Wellness .
“It’s incumbent on the pet owner to know what calories are in the food and the energy their dog needs,” Dr. Moser says. While weight and age are a good starting point for calculating what your dog requires maintain or lose weight, there are other important multipliers to take into consideration, such as whether your dog is spayed or neutered, and the intensity and duration of their daily activity. Also, pregnant or nursing dogs and puppies need more energy (aka calories).
A good way to set a calorie baseline is with a visit to your veterinarian. Since only about 17 percent of owners think their dogs are overweight, according to one study, the first step is breaking through denial. Your vet can help. There are several ways to set a daily calorie count, such as aiming for a one percent of total weight loss each week, or 75 percent of the calories required to maintain a goal weight, etc., Dr. Moser says.
The important thing is to be consistent and engaged. Once you cut back on calories, weigh your dog about every ten days, Dr. Moser says, to see when they plateau. Also, he recommends something called “body condition scoring .” The Ohio State University College of Veterinary Medicine website provides an illustrated chart that shows dogs and cats from emaciated to obese. Look at the pictures and ask: Where does my dog fit? You should be able to feel your dog’s ribs but your fingers shouldn’t fit between them.
Why diet food? Why not just feed your dog less of his or her regular food? “What makes a diet food different is we’re essentially diluting calories,” Dr. Moser says. There are only a couple ways you can do that including reducing fat content, which decreases calorie density and palatability, or adding fiber or even air, in the case of kibble. The calories in canned food can be diluted with water. “We are making dogs think they are full when they’ve really only eaten 75 percent of the calories,” Dr. Moser says. “The other stuff is just helping you feed more so the dog doesn’t beg.”
One reason Dr. Moser says people aren’t successful with low calorie food is because they leave it out for free-choice feeding. (Imagine a sort of bottomless bowl." “Because even low calorie foods have calories,” he says. He agrees with the study recommendation that free-choice feeding is not a good option—in part because food today is extremely palatable and so it’s easy for dogs to overeat. The better option is a measured quantity of food a couple times a day, he says.
If you don’t see calories listed on your label that’s because calorie counts are only required on dog food that claims to be lite, light, less calorie or low calorie. (The Academy of Canine Veterinary Nutrition, to which study co-author Dr. Lisa Freeman and Dr. Moser belong, is advocating for requiring calorie information on all pet food labels.) Foods with a light, lite, or low-calorie designation must also adhere to a maximum kilocalorie per kilogram restriction. However, Dr. Freeman pointed out that more than half of the foods evaluated in her study exceeded this maximum.
Why does it matter if your pup’s a little plump? Dr. Moser points to research that shows keeping dogs thin can extend their lives by as much as one and half years—that should motivate us to study labels and get out our measuring cups.