Weight Reducing Diets... Where Have We Gone Wrong?
--Written by: T.J. Dunn Jr, DVD
  Twenty years ago commercial diets appeared on the canine banquet table that were designed to promote weight loss. "Great," I thought. Lots of dogs were overweight so I jumped into the pool of promoters dispensing weight loss diets. 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 dogs' tummies full and appetites satisfied... and yet would result in a slimmer and healthier dog. Today, twenty years later, it is estimated that 35 percent of domestic dogs are not only overweight but actually obese.
  About ten years ago I began asking myself what happened. I had examined hundreds and hundreds of canine patients that were consuming various brands of "lite" or "reducing" or "senior" diets that target the overweight or less active dog. 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 firs; but eventually became discouraged with the results I was seeing and so were the dog's owners. In trying to figure out why these diets failed miserably in healthy dogs without 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 meals to dogs. But I have lost faith.
  I was consistently examining dogs being fed according to the label recommendations (and not being given treats) that 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 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. 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 link in the chain to weight loss was being overlooked in favor of key word marketing. We humans have been conditioned to think that fat intake promotes fat storage 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. Also the evocative key words "reduced fat" or "reduced calories" were splashed prominently on pet food labels and piggybacked on human nutritional concepts and perceptions.
  Almost all pet weight loss diets have a reduced protein and fat content; therefore, something else needs to take up the space in the ingredient recipe. So the pet food manufacturers added fiber to bulk up the diet so the dog would "feel full" on a lower calorie diet. The dog's meal was now less "calorie dense". Not a good idea, as it turns out, for a meat-eating animal such as a canine. Case, Carey and Hirakawa in their book CANINE AND FELINE NUTRITION, published by Mosby and Sons, 1995, state "Diets that contain increased levels of indigestible fiber and reduced levels of protein are not recommended for weight loss or for long-term weight maintenance of sedentary dogs and cats. If a diet is simultaneously high in indigestible fiber and low in fat and/or other nutrients, it is possible that long term feeding may result in nutrient deficiencies in some animals". Those last two sentences explained why I was seeing so many canine patients eating reducing diets that were developing dry, itchy, flaky skin and coats that were coarse and greasy and lacked luster.
  An ounce of fat has twice the calories as an ounce of protein or carbohydrate. Weight reducing diets contain increased amounts of carbohydrate from corn, barley, wheat and rice in place of the calorie rich fat. And since dogs convert protein to energy much more efficiently than humans, many weight loss diets for dogs also had reduced protein levels... and the protein calories were replaced with even more carbohydrate. An added bonus for the manufacturer is that carbohydrate ingredient sources are generally less expensive than sources of at and protein. So, intuitively, it seemed to make sense that canine weight loss diets should have less fat and protein and more carbohydrate. And over the last twenty years that is precisely how weight loss diets for dogs and cats have been constructed. The conclusion that came to me is this: Weight loss diets are carbohydrate based, and that's precisely why they're not working.
  CARBOHYDRATES
  Biology rules! I believe carbohydrate is the dominant nutrient driving the success or failure of a weight loss diet formulation for canines. Here's why: Ingested carbohydrate stimulates insulin secretion from the dog's pancreas every time the dog consumes such substances as corn, wheat, barley, rice, potatoes, fruits, vegetables or pasta. That's important, too because insulin is natural and necessary for life. But insulin, just like other chemicals in the body, does exactly what it is supposed to do. And one of those tasks is to promote the conversion and deposition of extra dietary carbohydrates (those not needed immediately for the day's energy consuming activities) into reservoirs of energy in the muscles and liver. Once those reservoirs are full, extra carbohydrate is directed by insulin chemistry to be modified a bit and deposited into the major energy reservoir called adipose tissue...fat. To simply, it can be stated that continuous exposure to excess carbohydrate results in conversion of the carbohydrate energy into fat. The same statement is not entirely true regarding excess protein in the dog's diet.
  PROTEIN
  An interesting and important fact of protein metabolism is that if the dog consumes more protein on a daily basis than needed for metabolic processes, energy needs, and tissue building and repair, the extra protein is excreted by the kidneys and not stored in the energy reservoir as fat. Unlike extra carbohydrate calories that are stored as fat, protein surplus is essentially eliminated.
  FAT
  Decreasing the fact content of weight-reducing diets to achieve a less calorie dense product may not be wise. It has been unbiased observation that a large percentage of dogs consuming these diets end up with dry, flaky and itchy skin, coarse and greasy coats, and even cracked nails and pads. Add some high quality fats and protein to the diet and these undesirable conditions disappear within three weeks. Not very scientific, I admit, but neither is increasing the carbohydrate content of a diet in place of high quality protein and fat in an effort to reduce the dog's fat reservoir!
  THE SOLUTION
  Weight management in dogs involves more than dietary considerations. Domestic dogs don't have to chase down their meals these days so they inherently experience less exercise and acquire more food than their wild predecessors. Human and canine behavior modification is an absolute necessity if a dog owner is to successfully reduce the dog's body weight to an optimum level. As David Kronfeld, DVM, PhD., a specialist in veterinary nutrition at Virginia Tech, University of Blacksburg, VA, relates, "In my experience the only worthwhile weight loss programs are lifestyle oriented--more exercise and less food, that is, a lower intake of a diet of the highest quality".
 

Gerry Nash, President and Founder of Animal Food Services in Green Bay, WI, has been producing and distributing meat based diets (high protein, moderately high fat and moderately low in carbohydrate) for nearly thirty years. Nash states, "In the wild, canines dine on raw meat diets they catch themselves and obesity is noticeably absent. Our company creates the same natural balance of nutrition in our raw meat diets. We have served these diets to an array of meat eating animals for nearly three decades and never experienced weight problems of any kind."
  Twenty years ago I was a proponent of cereal based, low fat, reducing-diets for body weight management in dogs. When I observed that in a substantial majority of cases these diets simply did not do what they were intended to do, and in some cases actually resulted in the opposite of what was expected, I rethought what made sense from a natural and biological standpoint. For dog owners whose dogs are overweight but portions of a diet composed of high quality protein sources, moderate percentages of high quality fat and low carbohydrate. Add exercise to the recipe and the weight reducing results are excellent and predictable.

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