Weight Reducing Diets For Dogs (and Cats)

By T. J. Dunn, Jr., DVM
September 15, 2009

Where Have We Gone Wrong?

Twenty years ago commercial diets appeared on the canine and feline banquet table that were designed to promote weight loss. Great, I thought. And since so many pets were overweight, I jumped into the pool of promoters dispensing pet weight loss diets from my animal hospital.

Pretty soon just about every pet food company produced and promoted their various brands of weight reducing diets in flavors, textures, colors and compositions that were sure to keep our pets' tummies full and appetites satisfied … and yet would result in a slimmer and healthier dog. The problem is that these reduced calorie or weight loss diets seldom worked.

Today, twenty-five years after the weight reducing diets first appeared, it is estimated that over 35 percent of domestic dogs and cats are not only overweight but actually obese!

I began asking myself what happened. I had examined thousands of dog and cat patients that were consuming various brands of "lite" or "reducing" or "senior" diets that target the overweight or less active pet. Essentially all of those reducing diets had added quantities of fiber and reduced percentages of fat and protein compared to maintenance diets, so, in theory, they should have worked.

In total honesty, though, I assert that I have seen less than ten patients actually lose weight on these weight-reducing diets. With equal honesty, I assert that many actually gained weight!

I believed in these diets at first, and I sold lots of them; but eventually I became discouraged with the results I was seeing and so were pet owners. In trying to figure out why these diets failed miserably in otherwise healthy dogs and cats not afflicted with thyroid or other metabolic dysfunctions, I have come to a few conclusions. Keep in mind that I started out a believer. I had no preconceived biases against the concept of feeding weight reducing pet foods to dogs and cats. But I have lost faith.

I was consistently examining patients that were not being given treats and were fed according to the label recommendations and yet were either not losing weight or were actually gaining! I set off on a personal search for the answer to this paradox. After all, I was recommending and selling these weight-reducing diets so I had a personal interest in seeing that whatever I sold or prescribed worked.

(I am reluctant to suggest to the pet owner to feed less than what is suggested on the package label because when one feeds less than indicated for a specific body weight, the minimum daily allowances of vitamins, minerals and essential amino acids and fats may not be met, and the dog will suffer from nutritional deficiencies. I’ve seen it happen.)

Even though no pet food producer guarantees their product will work as advertised, I felt I needed to stand behind whatever I sold or recommended. What I discovered was fairly simple and intuitive, and clearly made sense. It explained to me why so many patients failed to lose weight with the weight reducing diets.

Why They Failed

It is my opinion that a fundamental concept required in a successful attempt to achieve weight loss was being overlooked in favor of key word marketing strategies. We humans have been conditioned to think that fat intake promotes fat storage in the body and consequent gain in body weight. This is true and it makes sense.

So the pet food manufacturers created diets with decreased fat content partly because fat is calorie dense. (Removing a gram of fat from a pet food recipe and substituting something else such as protein or carbohydrate reduces twice as many calories from the recipe as would be reduced if carbos or protein were removed. 1 gram of fat contributes about 9 calories, 1 gram of carbohydrate and 1 gram of protein contribute about 4 calories each.) Manufacturers splashed the evocative key words "reduced fat" or "reduced calories" prominently on pet food labels and capitalized on current human buying trends and perceptions.

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