In the study published in the scientific journal Science, researchers found that changes in a particular gene altered the chemical signals that tell our brains we’ve had enough to eat.

Scientists found that the dog gene DENND1B, which is strongly associated with obesity in Labradors, is also linked to obesity in people.

"By studying dogs, we've honed in on some interesting new biology here,” lead researcher Dr Eleanor Raffan from the University of Cambridge's department of physiology, development and neuroscience said.

Raffan added that this discovery showed that “owners of slim dogs are not morally superior, and the same is true of slim people.”

"If you have a high genetic risk of obesity, you're prone to gaining weight unless you put a huge effort into not doing so. And those with low genetic risk just don't have to work so hard."

Researchers recruited dog owners. They measured the dogs' body fat, gave them a “greediness” score by measuring how much they pestered their owners for food, and took a saliva sample to test the DNA.

The dogs with DENND1B had 8 per cent more body fat than those without it.

Scientists then looked at whether the gene was relevant to human obesity.

They did this by looking at population-based studies and cohorts of patients with severe, early-onset obesity where single genetic changes are suspected to cause the weight gain.

Dr Raffan said, “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 behaviour and energy use.”

The study also found that owners who strictly controlled their dogs’ diet and exercise managed to prevent even their dogs with higher genetic risk from becoming obese, but much more attention and effort were required.

Researchers said that the same could be said for humans who have a high genetic risk of developing obesity: although they are more prone to weight gain, if they follow a strict diet and exercise regime, they will not necessarily become obese.

No single gene determines whether dogs or humans will be prone to obesity.