A study from the University of Cambridge has uncovered a genetic link between Labrador retrievers and humans that sheds new light on obesity. The research, published in the journal Science, identifies the DENND1B gene as a key player in weight regulation and appetite control, highlighting the shared genetic factors that contribute to obesity in both species.
The study pinpointed DENND1B as the gene associated with obesity in Labradors, a dog breed known for its insatiable appetite. Strikingly, humans also carry this gene, and researchers, after studying 241 Labradors, found that the particular gene plays a similar role in obesity among people. DENND1B affects the leptin melanocortin pathway, a critical brain mechanism that regulates energy balance and appetite. In addition to this key gene, four other genes associated with canine obesity were mapped directly to their human equivalents, further underscoring the genetic similarities between the two species.
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Dogs carrying the DENND1B genetic variant had approximately 8% more body fat than those without it. The researchers then extended it to human studies, examining large population-based datasets and patients with severe, early-onset obesity, where single genetic mutations may be a driving factor in weight gain.
“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,” caution researchers. “But the results emphasize the importance of fundamental brain pathways in controlling appetite and body weight,” explained Alyce McClellan, a joint first author of the report from the University of Cambridge’s Department of Physiology, Development, and Neuroscience.
The research also revealed that dogs at high genetic risk of obesity displayed a greater interest in food. “We found that dogs with a higher genetic risk were more persistent in seeking food from their owners,” said Natalie Wallis, another joint first author of the study. Similarly, humans with a genetic predisposition to obesity tend to experience stronger hunger signals, increasing the likelihood of overeating, particularly in environments with abundant food availability.
However, the study emphasizes that genetics alone do not determine obesity risk but even environmental factors play a crucial role. Dogs whose owners strictly managed their diet and exercise maintained a healthy weight, despite their genetic predisposition. This mirrors human experiences—people at high genetic risk can still avoid obesity through disciplined dietary habits and physical activity.
Obesity rates on rise
Obesity is a growing global crisis both in humans and companion animals. Recent studies estimate that 40-60% of pet dogs are overweight or obese, mirroring trends in human populations. Data from The Lancet reveals that as of 2022, more than 1 billion people worldwide are living with obesity, with projections indicating that by 2050, more than half of all adults and nearly one-third of children and young people will be affected. This equals 3.8 billion adults and 746 million children and adolescents among humans.
The current human obesity epidemic is paralleled by an obesity crisis in pets too. Overweight and obese dogs face a range of health problems, including diabetes, joint issues, and reduced lifespan. Understanding the genetic components of obesity in dogs provides valuable insights into human obesity and potential future interventions.
By analyzing DNA samples from Labrador retrievers and comparing their obesity status, researchers were able to identify the genetic variants linked to excessive weight gain.
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Dr. Eleanor Raffan, the lead researcher of the study, emphasized the importance of these findings. “This work shows how similar dogs are to humans genetically. Studying dogs allowed us to focus on this particular gene, leading to a major advance in understanding how our own brain controls eating behavior and energy use.”
While the latest findings need further research to alter the gene and stem obesity, studies in the last decade have frequently pointed to the singular most effective way to counter obesity — to restrict the intake of carbohydrates, and that the association between “junk food and sport, must end.”