Are You and Your Labrador Obese? New Research Finds a Surprising Link

Scientists researching Labrador retrievers have identified multiple genes linked to obesity in dogs, with findings that extend to human obesity as well. The study, published in the journal Science, presents a breakthrough in understanding how genetics influence weight gain and appetite regulation across species.

A growing epidemic in dogs and humans

Obesity remains a pressing global health issue, with the World Health Organization estimating that more than 1 billion people worldwide are classified as overweight or obese. This epidemic is mirrored in the canine population, where studies indicate that between 40 and 60 percent of companion dogs are overweight or obese. Excess weight in dogs, much like in humans, increases the risk of serious health conditions, including diabetes, heart disease, and joint disorders.

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As obesity rates continue to climb, researchers have turned to dogs as a model for studying weight gain. Dogs share many environmental factors with their human owners, from diet to lifestyle habits. Moreover, due to their genetic similarity within breeds, dogs offer a more controlled genetic model for studying obesity compared to the diverse human population.

The research team from the University of Cambridge pinpointed DENND1B as the gene most strongly associated with obesity in Labrador retrievers. Humans also carry DENND1B, and the study confirmed its connection to obesity in people as well.

DENND1B influences the brain’s leptin melanocortin pathway, a crucial system for regulating energy balance and appetite. Disruptions in this pathway can lead to increased hunger and a greater likelihood of weight gain. In dogs carrying the genetic variant linked to obesity, body fat levels were approximately 8 percent higher than those without the gene.

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Beyond DENND1B, researchers identified four additional genes linked to canine obesity, all of which have direct human counterparts. These genes, though less influential than DENND1B, collectively contribute to an increased risk of weight gain.

The study found that Labradors with a genetic predisposition to obesity exhibited a greater interest in food.

“We found that dogs at high genetic risk of obesity were more interested in food,” said Natalie Wallis in the University of Cambridge’s Department of Physiology, Development and Neuroscience, and joint first author of the report.

She added: “We measured how much dogs pestered their owners for food and whether they were fussy eaters. Dogs at high genetic risk of obesity showed signs of having higher appetite, as has also been shown for people at high genetic risk of obesity.”

These findings align with human obesity research, where individuals with a genetic predisposition to weight gain often struggle with heightened appetite and difficulty maintaining weight loss.

Weight management: the role of lifestyle control

While genetics play a significant role in obesity risk, they do not dictate destiny. The study found that strict control over a dog’s diet and exercise could prevent obesity even in genetically predisposed individuals.

Similarly, in humans, those with a high genetic risk of obesity can maintain a healthy weight through rigorous dietary management and exercise routines. However, doing so requires significantly more effort than for individuals with a lower genetic risk.

“Studying the dogs showed us something really powerful: owners of slim dogs are not morally superior. The same is true of slim people. If you have a high genetic risk of obesity, then when there’s lots of food available you’re prone to overeating and gaining weight unless you put a huge effort into not doing so,” said Eleanor Raffan, PhD, a researcher in the University of Cambridge’s Department of Physiology, Development and Neuroscience who led the study.

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One of the significant advantages of studying obesity in dogs is the ability to separate appetite from lifestyle influences, something much harder to do in human studies.

“By studying dogs we could measure their desire for food separately to the control owners exerted over their dog’s diet and exercise. In human studies, it’s harder to study how genetically driven appetite requires greater willpower to remain slim, as both are affecting the one person,” Raffan added.

To gather their data, researchers recruited dog owners, measured body fat percentages in participating dogs, and recorded behavioral traits such as food motivation and feeding habits. DNA samples were then analyzed to identify genetic patterns associated with obesity.

Once the canine genetic markers were identified, researchers cross-referenced them with human genetic studies. Their analysis included population-based studies and targeted investigations of individuals with severe, early-onset obesity, where genetic factors are suspected to play a dominant role.

Managing obesity in dogs and humans

The study’s findings offer insight into how pet owners and individuals can better manage weight despite genetic predispositions. Researchers suggest that pet owners with genetically at-risk dogs implement strategies such as using puzzle feeders, spreading out food portions throughout the day, and optimizing nutrient composition for satiety.

“Owners can keep their dogs distracted from constant hunger by spreading out each daily food ration, for example, by using puzzle feeders or scattering the food around the garden so it takes longer to eat, or by choosing a more satisfying nutrient composition for their pets,” the researchers advised.

A plant-based diet has also emerged as a promising tool for weight management in both humans and dogs. Studies suggest that plant-based diets, which emphasize whole foods such as vegetables, legumes, and whole grains, contribute to lower calorie intake and improved satiety. Fiber-rich plant foods slow digestion and enhance feelings of fullness, which can help prevent overeating. In humans, research has linked plant-based eating patterns to lower body mass index (BMI) and a reduced risk of obesity-related conditions such as heart disease and type 2 diabetes.

For dogs, plant-based diets formulated with high-quality protein sources like lentils, peas, and soy have been shown to support lean body composition and reduce the risk of obesity-related ailments. While dogs are omnivores, meaning they can thrive on both plant and animal-based diets, the key to effective weight management is ensuring balanced nutrition with appropriate macronutrient ratios. Veterinarians recommend plant-based diets as a suitable option for dogs with certain health concerns, including obesity and food sensitivities, provided the diet meets essential nutritional requirements.

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The findings reinforce the complexity of obesity as a condition influenced by both genetic and environmental factors. Understanding genetic predispositions can lead to more personalized approaches to weight management in both humans and dogs. While current weight-loss drugs do not target the genes identified in this study, the research underscores the role of fundamental brain pathways in appetite regulation.

“These genes are not immediately obvious targets for weight-loss drugs, because they control other key biological processes in the body that should not be interfered with. But the results emphasize the importance of fundamental brain pathways in controlling appetite and body weight,” said Alyce McClellan, PhD, in the University of Cambridge’s Department of Physiology, Development and Neuroscience, and joint first author of the report.

Raffan emphasized the broader significance of the study, stating: “This work shows how similar dogs are to humans genetically. Studying the dogs meant we had reason to focus on this particular gene, which has led to a big advance in understanding how our own brain controls our eating behavior and energy use.”