FGF21, or fibroblast growth factor 21, is a hormone secreted by the liver. It suppresses sugar and alcohol intake, stimulates the uptake of glucose by fat cells, and acts as an insulin sensitizer.

At least one variant of the FGF21 gene, rs838133, is associated with higher consumption of sugar and alcohol and lower consumption of fat and protein.

Approximately 20% of Europeans are homozygous for the rs838133 variant, and they consume more sugar and alcohol as a result. But, to what effect? A study published in Cell Reports investigates.

Study Pool

The researchers used data from 451,099 participants in the UK Biobank — all had Caucasian European ancestry.

The UK Biobank houses data on 500,000 people between 37 and 73 years. Biobank data was collected between 2006 and 2010 using surveys, interviews, anthropometric measurements, blood pressure readings, blood, urine, and saliva samples.

Sweet Tooth Gene and Body Fat

The good news for those with the "sweet tooth" gene is that the gene is associated with lower levels of body fat. The researchers of the abovementioned study reported lower levels of body fat "equivalent to 20g in a 100 kg person with 40% fat."

The bad news is — the rs838133 variant is associated with a higher waist-to-hip ratio, meaning individuals with the "sweet tooth" gene are more likely to have an apple shape — a shape typically associated with adverse health effects.

Sweet Tooth Gene and Diabetes, Blood Pressure, and Heart Disease

The "sweet tooth" gene was associated with high blood pressure. Yet, there was no association between the minor allele variant and Type 2 diabetes. There was also no association between the variant and heart disease.

Sweet Tooth Gene, Circadian Rhythms and Physical Activity

In a separate analysis, the researchers conducted a "phenome-wide association study," looking at the associations present between the FGF21 variant and 82 traits in the UK Biobank. The variant was associated with an evening chronotype and lower physical activity levels.

Don't Go Hog Wild on Sweets Just Yet

What do the results of this study mean? Here’s a breakdown:

Having intense cravings for sweets doesn't necessarily mean you have the "sweet tooth" gene. That said, if you do consume more sugar than the average person, there may be a genetic explanation for that behavior.

Although individuals with the FGF21 variant consume more sugar and alcohol, they don't appear to have an increased risk for heart disease or diabetes, and while they may have a lower body fat percentage, they also tend to have a higher waist-to-hip ratio.

These findings are interesting because, typically, the apple body shape is associated with an increased risk for heart disease and diabetes.

The results of the study don't permit us to eat as much sugar as we want. There's still plenty of evidence to suggest that a diet low in added sugar and high in fruits and vegetables is best.

Furthermore, the difference in body fat between those with the gene variant and those without wasn’t huge. You can't expect to eat lots of excess sugar and stay thin.

There is, however, reason for FGF21 to be further assessed as a gene-based therapy for specific health conditions.