One out of two companion animals is obese. This article explores how obesity, diabetes, and other chronic diseases intersect, and why they are on the rise in cats, dogs — and people.
Obesity and obesity-related diseases such as diabetes run rampant in our society. In 2017 and 2018, 42.4% of Americans were considered obese, a staggering increase from the 30.5% of two decades earlier. During the same time frame, severe obesity rose from 4.7% to 9.2% of the population.1 The numbers are even worse for cats and dogs. As of 2018, according to the Association for Pet Obesity Prevention (APOP), an estimated 56 million cats (58.9%) and 50 million dogs (53.9%) were considered overweight or obese.2 By effectively dealing with obesity in our animal patients, we can help prevent them from developing diabetes and a host of other weight-related problems.
High protein vs. high carbohydrate diets
High protein diets utilize protein for the continual maintenance of body tissues. When there’s more than necessary, the amino acids are used to produce glucose via gluconeogenesis. Gluconeogenesis is an energy-consuming process. Six moles of ATP are required to synthesize one mole of glucose from pyruvate or lactate.7 The additional ATP is needed to dispose of the nitrogen as urea. Cats, as obligate carnivores, are the superstars of gluconeogenesis. This process provides them with a steady low level of glucose.
Carbohydrates and companion animals
High carbohydrate diets utilize glucose for energy needs. But when cats consume excess carbohydrates, an unnatural cascade of events occurs. Cats have minimal glucokinase activity, which leads to prolonged hyperglycemia following a high carbohydrate meal, and prolonged hyperglycemia culminates in hyperinsulinemia.9 Eventually, insulin receptor resistance occurs as well.10 The scenario repeats with the next meal. This repeated glucose intolerance leads to obesity and inevitably Type 2 diabetes.11,12 High carbohydrate diets truly represent ultimate nutritional abuse for cats.
Canine pancreatitis is a common condition seen by the practicing veterinarian, and can be attributed to long term, high carbohydrate diets. The average dry dog food contains 41% carbohydrate. These high carbohydrate meals over-stimulate the pancreas to produce immense amounts of amylase. In fact, the amylase activity in the duodenum of a dog fed dry food was 8.5 times higher than in a dog fed a raw meat and lung diet.13 Chronic pancreatic over-stimulation of amylase activity takes its toll.
Reducing those numbers on the scale
Obesity can be addressed in one of four ways, though some of these methods are more effective than others.
1. Decrease energy per meal and increase activity
This absolutely works to reduce body weight. But pets hate it. And then their owners hate it even more, eventually giving in to the dog or cat’s begging. Plus, diets with reduced energy content may provide suboptimal levels of much-needed nutrients, especially protein.
2. Decrease energy per meal by increasing fiber levels
The literature features mixed reviews about the concept of bulk-induced satiety in pets. And unfortunately, most of these diets are still high in soluble carbohydrates, leading to the abnormal cascade of hormonal events. Even diets with reduced energy content due to fiber dilution may not provide all the needed nutrients, especially protein.14
3. Change the macronutrient proportions
Adjust the diet’s proportions from commercial dry pet food with its low protein, moderate-to-high carbohydrate content, to meals that are high in protein and low in carbohydrates.
Much of this research focuses on the effects on postprandial glucose and insulin levels, as well as the sensitivity of insulin receptors. After a high protein/low carbohydrate meal, both blood glucose and insulin levels stabilize throughout the day. Though weight loss is more gradual, there is also a recovery of insulin receptor sensitivity with fewer spikes in glycemia.15
Weight loss diets with high protein/low carbohydrate content have also been shown to preserve muscle mass during weight loss. The amount of fat reserves is diminished as muscle mass is conserved.16
Further, an increase in postprandial thermogenesis occurs with high protein/low carbohydrate meals. This effect is most likely due to the energy-consuming process of gluconeogenesis. The increased thermogenesis is also associated with weight loss.
The roles of leptin and adiponectin
Leptin and adiponectin also play essential roles in obesity-related inflammation.
- Leptins are satiety hormones that communicate how much fat is stored in the body and signal the dog’s brain to stop eating. Higher levels indicate the body has adequate fat stored; lower levels signify the need to eat.
- Adiponectin exerts anti-inflammatory properties on cells lining blood vessels; higher numbers are beneficial. Low levels of adiponectin (as found in obesity) are associated with inflammation, lipid abnormalities, insulin resistance, and increased risk of diabetes in humans.
In a recent study evaluating high protein diets in obese dogs, the leptin and adiponectin levels showed that these diets are associated with low postprandial peak leptin concentrations and the smallest decrease in adiponectin release.17 This research suggests that a higher protein diet may improve immune metabolic health and satiety in overweight dogs.
Glycemic index of carbohydrates
There is a strong association between low glycemic index foods and weight loss in humans, dogs, and cats.18 The highest glycemic food is sugar; rated at 100, sugar causes the highest rise in blood sugar two hours after eating. Potato and brown rice are high glycemic foods; corn and sweet potato are moderate glycemic foods; and grains such as sorghum and barley are low glycemic foods.The low glycemic foods provide a level of satiety by minimizing postprandial insulin rise and preserving the sensitivity of insulin receptors.19,20
Interestingly, according to APOP, of the 1,156 pet owners and 574 veterinary professionals surveyed, only 28% of pet owners and 20% of veterinary professionals felt that a low glycemic diet is healthier for dogs. Conversely, 62% of pet owners and 41% of veterinary professionals “did not know” whether it was healthier.
Whether dog, cat, or human, obesity and obesity-related chronic diseases are on the rise, and bordering on epidemic levels. Abundant research in dogs and cats supports that hormonal imbalance is associated with chronic high-carbohydrate consumption.21,22 The content of calories is important (see sidebar above), and without also evaluating the hormonal regulation of catabolism, thermogenesis, and macronutrient balance in the diet, we aren’t adequately serving the companion animals in our care. Feeding high protein/low glycemic index carbohydrate diets can promote and maintain weight loss, control obesity, and curb their preventable related diseases.
1“Obesity is a Common, Serious, and Costly Disease”. Centers for Disease Control and Prevention. https://www.cdc.gov/obesity/data/adult.html. Published 2020. Accessed May 14, 2020.
2Association for Pet Obesity Prevention. https://petobesityprevention.org/. Published 2020. Accessed May 14, 2020.
3Camacho Salvador, Ruppel Andreas. “Is the Calorie Concept a real solution to the obesity epidemic?”
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5Benjamin E, Muntner P, Alonso A, et al. “AHA 2019 Heart Disease and Stroke Statistics — American College of Cardiology”. https://www.acc.org/latest-in-cardiology/ten-points-to-remember/2019/02/15/14/39/aha-2019-heart-disease-and-stroke-statistics.Published 2020. Accessed May 14, 2020.
6“Obesity and Cancer Fact Sheet”. National Cancer Institute. https://www.cancer.gov/about-cancer/causes-prevention/risk/obesity/obesity-fact-sheet. Published 2020. Accessed May 14, 2020.
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13National Research Council, et al. Nutrient Requirements of Dogs and Cats. National Academies Press, 2006, p. 57.
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16Bierer T, Bui L. “High-Protein Low-Carbohydrate Diets Enhance Weight Loss in Dogs”. J Nutr. 2004;134(8):2087S-2089S.
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22Brunetto MA, Sá FC, Nogueira SP, et al. “The intravenous glucose tolerance and postprandial glucose tests may present different responses in the evaluation of obese dogs”. Br J Nutr. 2011;106 Suppl 1:S194‐S197.