What do studies say about FTO Check?

Studies on the FTO gene variant rs9939609, often included in 'FTO Check' tests, show a consistent but small association with body mass index (BMI). Each copy of the risk (A) allele increases BMI by approximately 0.3–0.5 kg/m². This effect is derived from large genome-wide association studies (GWAS) and observational data, primarily in European populations. However, the overall variance in weight explained by this single variant is minimal. Polygenic risk scores that include FTO and many other variants still account for only a small fraction of obesity risk. Lifestyle factors such as diet, physical activity, and sleep have a much larger impact on body weight. Therefore, while the FTO variant is a real genetic factor, it is not deterministic. DTC companies may overemphasize its importance. Consumers should not blame their genes for weight issues but rather focus on modifiable behaviors. The evidence is based on human observational and GWAS data, with moderate strength. Caveats include ancestry-specific effects and the need for replication in diverse populations. In summary, the FTO check provides some insight but is not a definitive predictor of obesity.