While the findings are counterintuitive, the UK researchers say that it makes sense as the same part of the genetic code makes people less likely to binge on fatty or other types of food.
“We were surprised that the version of the gene associated with eating more sugar is associated with lower body fat,” said the study’s lead, Professor Timothy Frayling, a molecular geneticist at the University of Exeter.
“This goes against the current perception that eating sugar is bad for health.”
But he added this wasn’t unadulterated good news for the sweet-toothed, as even though body fat was lower overall it was more likely stored around the hips and belly, where it could affect the organs and cause high blood pressure.
Around one in five Europeans carry the “A version” of gene FGF21, which has been known about since 2013 as one of the genetic markers that make people more likely to eat high-carbohydrate food.
This section of the DNA is responsible for a particular hormone, a chemical signalling molecule, which acts to suppress or cause cravings and regulate the metabolism of glucose sugars and their storage as fat.
To explore the effects of different types of FGF21 the Exeter team turned to the UK Biobank, a database of more than 500,000 people from the UK including blood, urine and saliva samples and lifestyle information.
They included 450,000 people in the study, published in the journal Cell Reports, 175,000 of which had completed a questionnaire on how frequently they ate different foods.
“Because this study has so many people in it, it gave us enough individuals to be confident in the associations we were seeing,” said Niels Grarup, an associate professor at the University of Copenhagen and one of the paper’s co-authors.
The FGF21 hormone, which is made mostly in the liver, has many functions and acts on the hypothalamus in the brain to suppress sugar and alcohol intake, stimulates glucose uptake by fat cells, and acts as an insulin sensitiser.
However, the analysis found “unequivocal statistical evidence” that FGF21 was linked to increase alcohol intake, along with higher sugar intake.
It was also associated with a very slight increase in blood pressure, and larger hip-to-waist ratio, meaning carriers had more fat around their midriff.
While the NHS warns having a larger stomach and love handles increases the risk of diseases like diabetes and heart disease the analysis found no association with diabetes and carrying the FGF21 gene.