Here's Why Your Birth Year May Affect Your Weight

Genetics and dietary habits oftentimes determine how much an individual will weigh. Yet could your birth year also have something to do with it? Recent findings published in the Proceedings of the National Academy of Sciences (PNAS) found that the impact of a variant in the FTO gene that was previously linked to obesity risk largely depends on birth year, with no correlation between gene variant and obesity.

"Looking at participants in the Framingham Heart Study, we found that the correlation between the best known obesity-associated gene variant and body mass index increased significantly as the year of birth of participants increased," said lead study author James Niels Rosenquist, MD, PhD, of the Massachusetts General Hospital (MGH) Department of Psychiatry, in a news release. "These results-to our knowledge the first of their kind-suggest that this and perhaps other correlations between gene variants and physical traits may very significantly depending on when individuals were born, even for those born into the same families."

Researchers at Massachusetts General Hospital analyzed data from participants in the Framingham Offspring Study that followed the children of participants in the original study gathered in 1971. All participants ranged in age from 27 to 63, ending during 2008.

They measured the participants' body mass index (BMI) eight times throughout the study period, examining the relationship between the FTO gene variants that had been inherited. Findings revealed a direction relation between the genes and obesity.
While reserachers were unable to identify environmental differences that may combine with FTO variants to increase the risk of obesity, authors noted that post-World War II factors, such as the increased reliance on technology and easy accessibility to high-calorie foods may be likely contributors to the obesity academic.

"Our results underscore the importance of interpreting any genetic studies with a grain of salt and leave open the possibility that new genetic risk factors may be seen in the future due to different genetically-driven responses to our ever-changing environment," Rosenquist concluded.

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