Therapeutic Fasting and Calorie Restriction

Dog fasting looking for food in a piece of furniture

For many of us, choosing to feed our dogs more like their wild ancestors is an easy choice.  Most people see value in choosing fresh, whole foods for their dogs instead of processed and cooked foods.  Only a small minority however, are willing to feed their dogs with the same frequency as their wild ancestors.

The verdict on the health benefits of fasting is out, in both human and canine research so it might be time to consider, at the very least, restricting your dog’s diet a few days per week.

“Fasting is not the same as starvation” says Nancy Scanlan DVM. “With therapeutic fasting, nutrient intake is enough to maintain vital tissues, like heart and muscle. Ideally, there will be an additional supply of co-factors for liver enzymes required to deal with the breakdown of fat and release of toxins that occurs. Starvation occurs when there are no reserves left in the body and insufficient intake of nutrients, so that vital tissues are broken down.”

“Wolves, the dog’s closest living relative, are a window into normal dog physiology (before modification by kibbled dog food, dog sweaters and doggie beds). An ongoing study of wolves reintroduced to Yellowstone National Park confirms that they “are adapted to … feast-or-famine foraging.” When hunting is easy, packs make a kill every two to three days. An elk is consumed in this order: first, organ meats, then major muscle masses, and finally bone and hide. In this case, at the end of the two or three day period, lower caloric value is consumed, and bones are eaten at the same time as hide, including the fur.”

The benefits of fasting include:

  • Fat from the body is metabolized and any waste products stored in that fat are released.
  • The liver is able to fully process the released waste products and excrete them through bile, or release the processed products into the bloodstream for elimination through the kidneys, decreasing toxic load in the body.
  • Mitochondria down-regulate, with fewer free radicals released from them
  • Decrease inflammatory molecules in so many different cell types. Inflammation underlies many degenerative diseases, and fasting or prolonged caloric restrcition have been shown to decrease the incidence of cancer, decrease or reverse arthritis, cognitive decline, type II diabetes, hypertension, dermatitis and liver, kidney and heart disease

Lifetime studies involving calorie restriction to 70 percent of a “normal” diet in Labrador retrievers have shown a decrease in incidence and severity of osteoarthritis of the elbow,1 shoulder,2 stifle3 and coxofermoral4 joints compared to controls, as well as increasing their lifespans by two years. Interestingly, in one study the amount of gross and histopathologic damage in the shoulder joints was greater than radiographic changes,5 so similar studies based on radiographic changes alone are not necessarily as reliable.

You might want to think about either fasting your dog now and again or reducing his amount of food for several days at a stretch.  Alternately, you could give him just a bone to chew on once a week, or even a bowl of fruit.  The health benefits are obvious and in the end, your dog will thank you for it!


1. Huck JL, Biery DN, Lawler DF, Gregor TP, Runge JJ, Evans RH, Kealy RD, Smith GK. A longitudinal study of the influence of lifetime food restriction on development of osteoarthritis in the canine elbow. Vet Surg. 2009 Feb;38(2):192-8.
2. Runge JJ, Biery DN, Lawler DF, Gregor TP, Evans RH, Kealy RD, Szabo SD, Smith GK. The effects of lifetime food restriction on the development of osteoarthritis in the canine shoulder. Vet Surg. 2008 Jan;37(1):102-7.
3. Kealy RD, Lawler DF, Ballam JM, Lust G, Biery DN, Smith GK, Mantz SL. Evaluation of the effect of limited food consumption on radiographic evidence of osteoarthritis in dogs.Am Vet Med Assoc. 2000 Dec 1;217(11):1678-80br />
4. Kealy RD, Lawler DF, Ballam JM, Lust G, Smith GK, Biery DN, Olsson SE. Five-year longitudinal study on limited food consumption and development of osteoarthritis in coxofemoral joints of dogs. J Am Vet Med Assoc. 1997 Jan 15;210(2):222-5.
5. Runge, op cit.

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