File this under strange science discoveries of the day: a gene associated with eating more sugar and drinking more alcohol has now also been linked with lower body fat, a finding that surprised even the researchers who discovered it.
At the same time though, variations in this particular FGF21 gene were also shown to lead to higher blood pressure, increased waist size, and a higher risk of type 2 diabetes.
All of which means that new treatments targeting the hormone produced by the FGF21 gene could offer a number health benefits.
The research could also change thinking on how our genetic makeup affects what we eat ,and what we crave in our diets.
"We were surprised that the version of the gene associated with eating more sugar is associated with lower body fat," says one of the team, molecular geneticist Timothy Frayling from the University of Exeter in the UK.
"This goes against the current perception that eating sugar is bad for health. It may reduce body fat because the same allele also results in a lower consumption of protein and fat in the diet."
The researchers tapped into a UK database of 500,000 individuals called the UK Biobank, combining recorded health information with urine, blood, and saliva samples. A total of 451,099 records were analysed for the purposes of this study.
"Because this study has so many people in it, it gave us enough individuals to be confident in the associations we were seeing," says one of the researchers, Niels Grarup from the University of Copenhagen in Denmark.
The team looked at relationships in the data between various versions of the FGF21 gene and diet, body composition, and blood pressure, revealing the link between lower levels of body fat and FGF21 alleles.
In particular, the "A version" of the FGF21 gene – around 20 percent of Europeans have the maximum two copies of it – was linked to higher sugar intake, higher alcohol intake... and lower body fat levels.
"Whilst this version of the gene lowers body fat, it also redistributes fat to the upper body, where it's more likely to cause harm, including higher blood pressure," says Frayling, though the blood pressure differences weren't substantial ones.
There's no one simple message here - just lots more valuable data for scientists to use in their studies of the FGF21 gene.
Researchers have been investigating the gene for several years, examining its possible links to obesity and how increasing the hormone it produces could help reduce the risk of obesity and associated conditions.
Now we know that FGF21 gene variations produce some surprising results in body fat levels – something that hasn't been considered before. The next stage is to work out exactly why that's happening, which could in turn aid drug development.
"Our studies could refocus those efforts by revealing potential benefits and unintended side effects of manipulating this hormone," says Frayling.
The research has been published in Cell Reports.