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Latest health and behavior news and advice from the veterinarians at Tufts University.

Features July 2018 Issue

How Come the Weight-Loss Food Has More Calories than My Dog’s Regular Food?

Just because a label sends the message that a food is good for weight control doesn't always guarantee it's lower in calories than other foods.

You switch your overweight dog from her usual food to one whose label suggests the kibble will help her slim down, yet she doesn’t lose an ounce. Maybe she even gains weight on this new food. How can that be? It’s because calorie levels for weight management foods for dogs are “all over the place,” says board-certified veterinary nutritionist Deborah Linder, DVM, who heads the Tufts Obesity Clinic for Animals.

When she led a study that looked at 44 dog foods with labels that suggested they could help an overweight pet slim down, calorie levels ranged from 217 per cup to 440 — more than a two-fold difference. If your dog was consuming a diet with, say, 375 calories per cup before you made the switch, she may now be eating a food with upwards of 400 calories in every cupful. No wonder the weight-loss diet isn’t working! “It’s very possible to buy a food labeled for weight control that has more calories than the food you’re currently giving,” Dr. Linder points out.

The study was published in the prestigious Journal of the American Veterinary Medical Association a number of years ago, but the problem remains the same today, Dr. Linder says.


Foods labeled “reduced calorie” have to be reduced in calories from the company’s standard food. But if the standard is extremely high in calories, the reduced-calorie formulation might still contain many more calories than could easily fit into a weight management plan.


 

The reason is that while there are regulations for how many calories can be in a weight management food according to the weight of the food itself, it’s common to see foods not following those guidelines, says Dr. Linder. Consider that for dog foods with a designation of “lite,” “light,” or “low-calorie,” the Association of American Feed Control Officials requires that it contain fewer than 1,409 calories per pound of food if it’s dry kibble and fewer than 409 calories per pound of food if it’s canned. (A lot of the weight of canned food comes from water, which contains no calories.)

But all bets are off for a food not labeled lite, light, or low-calorie and instead says “weight loss,” “weight management,” “overweight,” “calorie reduction,” “obese prone,” “to maintain healthy weight,” “avoid unwanted weight gain,” “lose excess weight,” or “reduced calorie” (phrases found by Dr. Linder on dog food labels in supermarkets, pet supply stores, and other outlets). “It’s easier to avoid those calorie limits” with such wording, Dr. Linder says.

What it amounted to in the study was that more than half of the foods whose labels suggested they were weight management products contained more calories per cup than those with the legally regulated terms “lite,” “light,” or “low-calorie.”

Recommended feeding guidelines differ along with the calorie levels in the food

If very different calorie levels in weight management foods don’t make matters difficult enough for someone trying to get their pet to a healthy weight — or keep her at one — daily calorie intake recommendations also vary considerably from label to label, as evidenced by feeding recommendations. Based on the number of daily cups of food that should be fed to a dog as advised on packages, your pet could be taking in twice as many calories eating some products versus others.

“I totally understand why people have trouble getting their dogs to lose weight,” Dr. Linder says. “There’s a lot of confusing information out there.”

What’s the owner of an overweight dog to do?

Two main rules of thumb

In the face of a lack of regulation about many terms on dog food labels meant to suggest that they can help with weight management, along with the lack of standards on feeding recommendations posted on labels for how many calories a dog should be fed daily to reach or maintain ideal body weight, Dr Linder offers two very pragmatic rules of thumb.

The first regards how many calories should be in a cup of the food. Calories per cup is now required by law on all dog food labels, although it wasn’t when Dr. Linder conducted her study, so there has been progress, and it is now easier to make choices.

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Willee Cole | Bigstock

It can be hard to keep an overweight dog from tipping the scale if the “diet” food doesn’t have fewer calories than your pet’s regular food.

“I tend to tell people generally speaking that if their dog needs to lose weight, they should pick a product that has 300 calories per cup or less. It’s just a general guideline, not evidence-based. But it’s often a reasonable starting point.”

2 Dr. Linder’s second rule of thumb kicks in if the weight management food you’ve chosen doesn’t do the trick unless you start going well below the recommended serving size listed on the package. It’s then time to speak to your veterinarian about getting a food by prescription from the veterinarian — a therapeutic food — that has fewer calories per cup than the over-the-counter food you’ve chosen.

When a pet food manufacturer recommends a certain amount of food per day, Dr. Linder says, it is taking into consideration all the vitamins, minerals, and other nutrients in the food, including protein. If you begin feeding much less than what the package advises, you are cutting not only calories but also essential nutrients a dog needs to stay healthy.

Weight management foods available only by prescription from a veterinarian tend to be significantly lower in calories than over-the-counter “diet” foods — often closer to 200 calories per cup than 300 or 400, “but they are formulated to pack in a lot of nutrients for every calorie, so when you cut the calories with these foods, the dog is still getting enough nutrients,” Dr. Linder says.

When to go it alone, when to involve your dog’s general vet, and when to see a veterinary nutritionist

If a dog is, say, just 10 percent overweight, maybe a 6 on the Body Condition scoring system that ranges from 1 to 9 (a 4 to 5 is ideal weight — your vet can tell you where your dog scores during a routine office visit), you may very well be able to get her to ideal weight on your own, just by switching from her current food to one that is lower in calories. It’s easy enough to check calorie levels on bags and cans of dog food.


For guidelines on determining whether your dog is overweight, go to vetnutrition.tufts.edu, click on the “Petfoodology” tab,” and type “how do I know if my pet is overweight” in the search bar on the lower right. That will be one of the items that comes up.


 

But if your dog is at least 20 to 30 percent over ideal weight, you’re going to want to work with her doctor to determine what food can best meet her needs for calories and for essential nutrients. It’s in those cases that the calorie levels on over-the-counter diet foods are probably just not going to be at a low enough level to allow her to make much headway with slimming down — unless you start feeding much less than is recommended.

A veterinarian will also help you determine whether your dog needs enough nutrients to cover her requirements at the weight she’s at or the weight you want to achieve. There’s some nutrient-hungry muscle added when a dog gains weight, not just fat, Dr. Linder says. And if a dog has severe calorie restriction needs, the veterinarian can determine whether calories should be restricted gradually rather than all at once to ensure that there’s no risk for nutrition deficiencies as the pet diets down.

Should you be referred to a board-certified veterinary nutritionist as well? Not in every case, Dr. Linder says. “A veterinary nutritionist should come on board for the challenging cases — those in which switching to lower-calorie food doesn’t work; if the overweight dog has other diseases that makes selecting the right diet more complicated or restricted; or if there are unique situations such as other pets in the household whose food has to be kept away from the dieting dog in question. Not every overweight dog has to see a specialist.”

Beyond choosing the kibble

There’s more to trimming down an overweight dog than just giving her a lower-calorie food. In fact, Dr. Linder says, “I would be very remiss if I did not make this point: almost every dog that is referred to me — their owner thinks that if they just switch the food, it will magically change things. But it’s not just the dog food. It’s the total diet. If you’re still feeding 500 calories a day in treats, bones, and chews, unless you change that, it’s not going to do anything. In fact, if you lower the calories in your dog’s food by switching her to one for weight control but don’t limit her snacks, a larger proportion of your pet’s calories are coming from foods that are not balanced in terms of nutrition — snacks are not formulated with nutrient needs in mind — and your pet could end up with nutritional problems.

“You also have to carefully measure how much of the weight management food you are providing,” Dr. Linder says. “People will come to me and say, ‘we free feed the weight management food.’ That won’t work.” Indeed, research has suggested that 30 to 40 percent of dogs will overeat and become overweight or even obese if provided food ad libitum. The same can be presumed about weight loss; it will not happen if the dog is allowed to eat at will.

It’s important to bear in mind, too, that with many dogs who lose weight, the lower-calorie diet you’ve chosen for them may be for life. This is especially true for dogs who happen to be “easy keepers” and simply don’t need a lot of calories to sustain themselves. “We all have that friend who can eat a lot of calories because her metabolism is high and she will burn it all off,” Dr. Linder says. And then the next person can barely look at food without gaining weight. It’s true for dogs as well, she says, and owners of those who don’t need a lot of calories often like to keep their pet on lower-calorie weight-management food so they can feed more of it rather than relegate the dog to eating minuscule portions of food not formulated for weight management.

“It’s trial and error,” Dr. Linder says. Once your pet arrives at her ideal body condition, you need to experiment. If she starts gaining weight back, it’s clear that the weight-loss plan should also be the weight maintenance plan.

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