It’s well known that some people seem to be naturally skinny.
While some agonize over calorie counting and exercise to maintain their figures, others hardly have to pay attention to their diets to stay slim, all while staving off chronic disease.
Now scientists say it’s not just luck, but could actually be down to a single ‘skinny gene’ that may help thousands of Americans keep excess weight off, even without dieting or GLP-1 drugs.
In a new study, researchers looked at Folliculin Interacting Protein 1, or FNIP1. Normally this gene regulates cellular energy and metabolism, controlling how cells burn or store fuel.
But one in 7,000 people, or one million worldwide, carry a broken copy of this gene that means the body burns calories more easily.
The team, from Regeneron Genetics Center in New York, analyzed genetic data from more than one million people across three continents, finding 150 participants with an FNIP1 mutation.
Researchers found those participants had lower blood sugar, decreased cholesterol, less fat around their livers and about a 60 percent lower risk of metabolic conditions like obesity and diabetes.
This had nothing to do with classic weight loss measures like diet and exercise. Instead, they were simply burning more calories due to the mutation.
A rare gene mutation has been shown to help burn more calories, aiding weight loss and reducing the risk of heart and other metabolic diseases
‘These individuals consume, store and utilize energy more efficiently than individuals without those mutations, and that’s the protective factor,’ Luca Lotta, study co-senior author and geneticist at Regeneron Pharmaceuticals, told Scientific American.
‘Nowadays, we are living in a very calorie-rich environment, and historically there’s no precedent for this,’ he said.
‘These incredibly rare mutations, which might have been unfavorable for many millennia, are now favorable to the body.’
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The only way to conclusively determine that you have the gene is to get genetic sequencing blood tests, which can cost anywhere from $1,000 to $2,000 out of pocket depending on insurance.
About 48,000 Americans have the mutation, researchers estimate.
The team say their work could help with the development of new weight loss drugs that mimic the effect of shots like GLP-1s.
In the new study, published in the journal Nature, scientists performed DNA sequencing on just over one million participants from major research cohorts, including the UK biobank database, in North America, Europe and Asia.
They also measured levels of blood lipids such as cholesterol and triglycerides, blood sugar, blood pressure and C-reactive protein, which measures inflammation levels in the liver.
Additionally, they measured differences in participants’ body fat, muscle mass and history of liver, kidney and heart disease.
The team found that people with one faulty copy of the FNIP1 gene had lower cholesterol, triglycerides, liver fat, blood sugar and body fat than non-carriers.
They also had less liver and overall body fat, as well as a healthier distribution of fat.
People with the mutation also had a 60 percent lower risk of developing cardiometabolic diseases, which include coronary artery disease, type 2 diabetes, metabolic dysfunction-associated steatotic liver disease (MASLD) and liver cirrhosis.
The researchers then tested if silencing FNIP1 in liver cells could turn on fat-burning genes. In mice fed a fatty, sugary diet, altering the gene curbed weight gain, reduced fat and improved insulin sensitivity. Over 30 weeks, it prevented liver scarring.
Notably, however, inheriting two broken copies of FNIP1 instead of just one did not have protective effects. Instead, it had the opposite outcome, increasing vulnerability to heart disease and immune deficiency.
‘If you were to therapeutically inhibit the gene everywhere in the body at 100 percent, that could have a negative impact on health,’ Lotta said.
He notes that targeting the gene in the liver may help mitigate those risks but cautions that any ‘therapy is many years away.’
