What can dogs tell us about genetic causes of obesity in humans?

Experts have long known that obesity and genetics are closely linked. For some of us, a tendency to overeat is quite literally written in our DNA.

A paper from 2023 lists more than 20 genes that can contribute to obesity. If a person has one or more of these genes, it means they're more at risk of developing the disease.

And now, with a little help from 241 Labrador retrievers, scientists have identified another gene that plays a role in hunger, overeating and obesity risk.

It's called 'DENND1B'. Let's put it under the microscope.

What the researchers discovered

Did you know that humans and dogs share around 84% of their DNA?

It's a similar story with other mammals like cats (90%), pigs (98%) and chimpanzees (98.8%). Although these species may appear to be very different, the basic building blocks of life remain remarkably similar across huge swathes of the animal kingdom.

It's one reason scientists often use animals as stand-ins for humans when conducting genetic research. If they want to study a particular gene in humans, they can look at the same gene in mice, rats or dogs instead.

That brings us to the new study. The researchers wanted to learn more about the genetic causes of obesity and how it can be passed down from one generation to the next.

So, they studied the family trees of 241 Labrador retrievers, looking for genetic markers that appear in dogs with obesity and their parents or offspring.

The DENND1B gene, they found, cropped up in many overweight labradors. And when they searched through human genetic databases, they discovered that the same gene appears in people with a tendency to have overweight or obesity.

What does this mean?

Scientists are striving to fully understand the genetic causes of obesity in humans. However, they're not quite there yet. This new study brings us one step closer to that goal.

And just as importantly, it adds weight to the notion that people are not the architects of their own obesity. As experts have long argued, obesity is not caused by laziness or a lack of willpower – some people are simply genetically predisposed to the disease.

As researcher Dr Eleanor Raffan told the BBC, these people are 'prone to gaining weight unless [they] put a huge effort into not doing so'.

'Those with a low genetic risk just don't have to work so hard', she added.

The discovery is also helping us understand the role of the brain in overeating and obesity risk. Dr Raffan and her team learned that the DENND1B gene is linked to neural pathways that regulate appetite.

While they target different pathways, weight loss injections like Wegovy and Mounjaro also work – in part – by influencing how our brains respond to food.

'What we've identified here is a different pathway [from the one targeted by those drugs]', Dr Raffan explained. 'But it all speaks to the same important bit of biology, which is that obesity is not about having low willpower.'

SemaPen is a weight loss clinic specialising in expert-led obesity treatment programmes. Follow our blog for the latest news on Mounjaro, Wegovy and breakthroughs in obesity research.

Sources

1. Masood, B. & Moorthy, M. (2023) "Causes of obesity: a review" Clinical Medicine, 23(4) https://doi.org/10.7861/clinmed.2023-0168

2. Wallis, N.J. et al. (2025) "Canine genome-wide association study identifies DENND1B as an obesity gene in dogs and humans" Science https://doi.org/10.1126/science.ads2145

This article was reviewed and approved on 24 March 2025 by Alice Fletcher, Lead Bariatric Dietician, and Lujain Alhassan, Bariatric Nutritionist.