The discovery goes some way to explaining why some people find it more difficult to lose weight than others. They are genetically predisposed to be overweight or obese because they expend less energy when at rest.
But if you’re someone who’s found it hard to lose weight in the past, don’t jump too readily at the chance to use this as an excuse. Those with the variant makeup a small proportion of the population, according to the researchers.
Scientists discover a new cause of why certain people are predisposed to be overweight
Researchers led by a team at the University of Exeter have discovered people with a genetic variant that disables the SMIM1 gene have higher body weight.
It’s because they expend less energy when resting. It seems to have an impact on metabolism, which causes the body to burn fewer calories during periods of inactivity.
The initial discovery of the SMIM1 gene took place just 10 years ago. It happened during the search for another gene, known as Vel. People who lack the Vel gene, i.e. who are “Vel-negative,” are about 1 in 5,000. It’s believed that they, too, are more likely to be overweight.
People without the SMIM1 gene tend to have high levels of fat in the blood, signs of fat tissue dysfunction, increased liver enzymes as well as lower levels of thyroid hormones, according to the University of Exeter’s news webpage.
Obesity rates have ballooned in the last 50 years
The study’s lead author, Mattia Frontini, emphasized skyrocketing obesity rates when explaining the importance of the present research.
“Obesity rates have nearly tripled in the past 50 years,” he said. “By 2030, more than 1 billion individuals worldwide are projected to be obese. The associated diseases and complications create significant economic burden on healthcare systems.”
Being severely overweight is the result of a “complex interplay of lifestyle,” i.e., the foods you eat and how much activity you engage in, “environmental, and genetic factors,” he added. And, in a small minority of people, genetic variants are the primary cause.
“Our findings highlight the need to investigate the genetic cause of obesity,” Dr Frontini said, “to select the most appropriate and effective treatment, but also to reduce the social stigma associated to it.”
How many people does the SMIM1 variant affect?
Researchers analyzed the genetics of nearly half a million Brits and identified just over 100 people with the variant that leads to the loss of function of the SMIM1 gene. The gender split was about 50/50.
They also worked in partnership with NHS Blood and Transplant. Expanding on the numbers they found in their study, they estimate that the SMIM1 genetic variant could be a “significant factor” contributing to obesity for about 300,000 people in the world.
Among the people they studied, the variant seems to have accounted for an average extra 10lbs (4.6kg) in females and 5.3lbs (2.4kg) in males.
One of the study’s co-authors said it was “very exciting” to find that the variant has a “more general role in human metabolism” than was previously thought.
