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Nutrition Nuggets is the newest offshoot of petMD's Dog Nutrition Center. Each week Dr. Coates will use her expertise and wisdom to blog about the intricacies of dog nutrition.

Deciphering Diet Pet Foods (Part 1)

April 26, 2013 / (3) comments

Have you ever purchased a so-called “diet” pet food? It may have been labeled as “light,” “lite,” “low calorie,” “reduced calorie,” or something similar, but all of these products infer that by purchasing the food in question, owners can help their pets lose weight.

If you have fed a diet food to your dog or cat per the label instructions but meaningful weight loss remained elusive, you’re in good company. I hear this complaint from clients on an almost daily basis. Why? Once we’ve ruled out caregivers and pets “cheating” on the diet, I am quick to blame the perplexing way these products are labeled.

The Association of American Feed Control Officials (AAFCO) does have standard definitions for some terms. For example, foods labeled as “light,” “lite,” or “low calorie” must not contain more than 3100 kcal/kg for dry dog food and 3250 kcal/kg for dry cat food. On the other hand, foods described as “reduced calorie” don’t have to abide by the same guidelines so long as the label indicates which foods are being compared. Therefore, if the manufacturer uses a food with high caloric density as the baseline, its “reduced calorie” version could still be very fattening.

A study published in 2010 took a look at the variability that exists in “diet” pet foods.

Commercially available diets for cats and dogs that might be purchased for weight loss on the basis of label information were included in the study. Various types of locations were surveyed that reflected common locations at which consumers would be able to obtain diets designed for weight loss of pets, including 2 pet specialty stores, 1 discount mass merchandiser, 1 supermarket, and 1 veterinary hospital. A range of label descriptions implying weight loss was accepted, such as the terms weight loss, weight management, overweight, or calorie reduction and images representative of overweight body condition. Diets were allocated into 2 categories: diets with weight management claims and feeding directions for weight loss and diets with weight management claims on the label but no specific feeding directions for weight loss. Label statements in the second category of diets included obese prone, to maintain healthy weight, avoid unwanted weight gain, lose excess weight, and reduced calorie.

The researchers found the following caloric densities in the foods they examined:


Those are huge ranges, and unfortunately the feeding directions printed on the label weren’t very helpful either. The recommended caloric intake varied between 0.73 to 1.47 times their resting energy requirements (RER) for dogs and 0.67 to 1.55 times RER for cats. A standard recommendation is that dogs needing to lose weight should be fed at their RER and cats at 0.8 times their RER.

It’s no wonder that helping pets lose weight is so frustrating! Pick the wrong food and you may very well be offering more calories than your dog or cat was taking in previously. If you’re interested in some tips on how owners can use these numbers to actually help dogs and cats slim down, check out today’s Nutrition Nuggets for cats.

Dr. Jennifer Coates


Linder DE, Freeman LM. Evaluation of calorie density and feeding directions for commercially available diets designed for weight loss in dogs and cats. J Am Vet Med Assoc. 2010 Jan 1;236(1):74-7. 

Image: WilleeCole / via Shutterstock

Comments  3

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  • Caloric Densities
    04/26/2013 05:56pm

    Interestingly enough I recognize the 235 calorie food in the dry cat food category. We use that as the main grazing food in our house because the cats' health does just fine on 1/2 cup of that, (118 calories per day). We would need more than one can of the canned foods that have reasonable ingredient lists, and no matter what treats we feed in the canned food category, they all have guar gum as the fermentable fiber. Guar gum is supposedly one of the worst fermentable fibers for cats and dogs. The wrong fermentable fiber reduces the animal's ability to absorb nutrients from the gut, so malnutrition happens, AND about 70% of the immune system is supported by good gut health.

    Also, just a note on the feeding instructions accompanying pet foods, I was told by Deb Zoran that those figures are created from tests done with intact male cats. Is that correct? As well, I have some training in nutritional assessment, can work out what should be quoted as being in a specific food, and sometimes when I break it down by nutrients the figures just don't add up. Sometimes we just have to go by whether our pets are maintaining healthy weight when judging how much to feed. In the dietitian's world that is called "portion control."

  • 04/26/2013 07:34pm

    Great question. I don't know whether or not intact male cats are used in feeding trials, but if they are, that would certainly affect recommendations regarding the amount that should be fed. Anybody else out there know?

    And I agree with you, all feeding recommendations need to be balanced by common sense parameters like how the pet is doing on the diet.

  • Marketing!
    04/26/2013 08:49pm

    It's all in the marketing and the word or words the public sees on the package.

    The pet food companies are doing a bang-up job in the marketing department, aren't they?