Find it impossible to stay slim? It could be down to a newly discovered fat gene that makes you 10lbs heavier… and experts say they may already have a cure

Scientists have discovered a genetic defect that makes you more likely to be overweight or obese – but there may be a cure.

Experts from the University of Exeter found that people with a faulty gene called SMIM1 burn less energy when resting, putting them at a huge disadvantage when trying to maintain a healthy weight.

On average, women with the condition are 4.6 kg heavier, and men have 2.4 kg of extra fat.

The defect is found in individuals with the rare blood group Vel negative, which is thought to affect around one in 5,000 people.

People with the condition burn less energy while resting, putting them at a huge disadvantage in maintaining a healthy weight

They are more likely to be obese and overweight, but the researchers think there may be an answer.

It is hoped that an inexpensive and widely available drug for thyroid dysfunction called levothyroxine may help obesity with the SMIM1 gene deficiency.

Professor of cell biology Mattia Frontini, from the University of Exeter Medical School, said: ‘The number of obese people has almost tripled in the last fifty years, and by 2030 more than a billion people worldwide are expected to be obese.

“The associated diseases and complications place significant economic burdens on healthcare systems.

‘Obesity is due to an imbalance between energy intake and expenditure, often a complex interplay of lifestyle, environmental and genetic factors.

‘In a small minority of people, obesity is caused by genetic variants. When this is the case, new treatments can sometimes be found that will benefit these people.

‘We now hope to conduct a clinical trial to find out whether a widely available thyroid replacement drug could be useful in treating people who lack SMIM1.

‘Our findings highlight the need to investigate the genetic cause of obesity, to select the most appropriate and effective treatment, but also to reduce the social stigma associated with it.’

The proportion of Britons who are overweight or obese has grown slowly over time, reaching two-thirds in 2021, the latest available data shows. No data has been recorded for 2020, the year of the Covid pandemic

Obesity affects around a quarter of all adults in Britain and increases the risk of conditions such as type 2 diabetes, stroke and coronary heart disease.

The new research, published in the journal Med, was funded by the National Institute for Health and Care Research and the British Heart Foundation.

The team analyzed the genetic data of nearly 500,000 individuals and identified 104 people with the loss-of-function variant in the SMIM1 gene.

Using blood samples from both Vel-negative and positive individuals, they also found that people with the SMIM1 deficiency often have other conditions associated with obesity.

These include high levels of fat in the blood, signs of adipose tissue dysfunction, elevated liver enzymes and lower levels of thyroid hormones.

The collaboration included researchers from the University of Cambridge, the Sanger Institute, the University of Copenhagen in Denmark and Lund University in Sweden.

Jill Storry from Lund University said: ‘SMIM1 was only discovered ten years ago as a long-sought blood group protein on red blood cells, but its other function has remained unknown until now.

‘It’s very exciting to discover that it plays a more general role in human metabolism.’

Professor Ole Pedersen from the University of Copenhagen, Denmark, said: ‘The whole team is very much looking forward to seeing how this new knowledge can be translated into practical solutions for people with this genetic makeup.’

Dr. Luca Stefanucci from Cambridge said: ‘With the increased availability of genetic data and more information about the SMIM1 mechanism, we would like to see that when individuals without SMIM1 are identified, they are provided with information and support.’