Obesity is an important disease with a growing incidence in the companion animal population. In the past decade, petfood companies have been formulating diets that are low-carb, high fiber, all protein, lean protein or calorie conscious, in hopes of wooing pet parents struggling to help their pets shed those extra pounds. But what does the latest research in dog and cat obesity have to say? Are diets such as the Green Bean Diet and the Catkins Diet fads like their human food predecessors, or real solutions for overweight pets? What are the benefits of helping your animal lose weight—could exercising with a pet actually improve both the owner and the animal's health? Let's investigate.
The results of a recent study in the Vet Journal (A.J. German et al.) indicate demonstrable improvement in health-related quality of life for obese dogs that successfully lose weight. Obesity has been thought to affect quality of life in companion animals, but limited objective data existed prior to this study to support this idea. This particular study used a questionnaire to determine health-related quality of life (HRQOL) before and after weight loss in 50 obese client-owned dogs representing a variety of breeds and genders.
Prior to weight loss, owners were asked to complete a validated standardized questionnaire to determine HRQOL. Thirty dogs successfully completed their weight loss program; owners then completed a follow-up questionnaire. The responses were transformed to scores corresponding to each of four factors (vitality, emotional disturbance, anxiety and pain) and scored on a scale of 0–6. Dogs that failed to complete their weight loss program had lower vitality and higher emotional disturbance scores than those successfully losing weight. In the 30 dogs that completed, weight loss led to an increased vitality score and decreased scores for both emotional disturbance and pain. However, there was no change in anxiety. The change in vitality score was positively associated with percentage weight loss and percentage body fat loss. These results indicate demonstrable improvement in HRQOL for obese dogs that successfully lose weight.
And animals of the four-legged variety aren't the only ones who benefit from weight loss. According to the Human Animal Bond Research Initiative Foundation (HABRI), pet parents who regularly exercise with their pets experience improved physical, emotional and mental health. HABRI plans to identify and fund new research topics, establish an education center, foster government relations and create a support network for pet parents in the future.
Another recent study investigated the influence of dietary supplementation with L-carnitine on metabolic rate, fatty acid oxidation, weight loss and lean body mass (LBM) in overweight cats undergoing rapid weight reduction (S.A. Center et al., AVJR 2012). Thirty-two healthy, neutered, colony-housed cats were fed an energy-dense diet unrestricted for six months, then randomly assigned to four groups and fed a weight-reduction diet supplemented with 0 (control), 50, 100 or 150 μg of carnitine/g of diet. Following weight loss, cats were allowed unrestricted feeding of the energy-dense diet to investigate weight gain after test diet cessation.
Median weekly weight loss in all groups was 1.3%, with no difference among groups in overall or cumulative percentage weight loss. During restricted feeding, the resting energy expenditure-to-LBM ratio was significantly higher in cats that received L-carnitine than in those that ate the control diet. Respiratory quotient was significantly lower in cats that received L-carnitine on day 42, compared with pre-diet, and in all cats that received L-carnitine compared with the control group. A significant increase in palmitate flux rate in cats fed the diet with 150 μg of carnitine/g relative to the control group on day 42 corresponded to significantly increased stoichiometric fat oxidation in the L-carnitine group (over 62% vs. 14% for the control group). Weight gain (as high as 28%) was evident within 35 days after unrestricted feeding was reintroduced. Dietary L-carnitine supplementation appeared to have a metabolic effect in overweight cats undergoing rapid weight loss that facilitated fatty acid oxidation, the study concluded.
Overweight and obesity are linked to insulin sensitivity and, subsequently in older cats, to an increased risk of developing diabetes mellitus (Häring et al., 2012). According to some, the Catkin's Diet is the ideal diet to combat this dual problem in felines. Starch and fiber in diets stimulate the formation of struvite crystals. The Catkin's Diet attests that reducing dietary carbohydrate is desirable to prevent struvite urolith formation. In addition, a net loss of body calcium, phosphorus and magnesium during feeding of the fiber diet suggests that dietary inclusion of insoluble fiber could increase macromineral requirements of cats. The diet consists of high protein and low carbohydrates and recommends no dry food and only canned, wet food or a raw diet. The ideal canned cat food should have less than 10% carbohydrates to meet the Catkin's Diet. According to the Catkin's theory, a diet that has low carbohydrates and high protein creates a better chance for your diabetic cat to go into remission, while also losing weight.
Another buzzworthy diet, this time directed at dogs, is the Green Bean Diet, which first appeared on petMD.com. According to Dr. Ken Tudor, in its simplest form, pet owners supplement 10% of the volume of their pets' regular canned or dry meal with canned green beans. The green bean content of the meal is increased in 10% increments every two to three days until all meals consist of 50% regular food and 50% green beans. This final mixture is fed until the pet's target weight is reached. The pet is then slowly weaned from the beans and back to all regular food. Studies in humans, cats and dogs have all substantiated positive weight loss results when adding fiber to calorie-restricted programs, according to Dr. Tudor. Human subjects report a greater sense of satiation or "fullness" with the fiber addition and tend to eat less if given free access to food. The same response in cat and dog subjects suggests that fiber has the same satiation effect.
But Dr. Tudor also warns that a 50% reduction in calories could be too severe. "Putting an animal on such a program without veterinary supervision or preliminary lab work could result in serious medical problems for any age group and especially those with undiagnosed medical conditions (liver problems, kidney problems, heart problems, diabetes, hypothyroidism, etc.)," he says. Adding green beans to a regular food diet could result in significant nutrient deficiencies, especially if the dieting was prolonged. This malnutrition is exacerbated by the fact that high dietary fiber interferes with the digestion and absorption of some essential fats, calcium, zinc and iron. Dr. Tudor says diets like Catkins and the Green Bean Diet can be helpful, but pet owners need to consult with their veterinarian. Petfood companies should also take a cue and provide their own nutrition information regarding such diets.
