What Your Birth Year Says About the Risks of Becoming Obese

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How influential is our year of birth in terms of determining the direction of our health? Is there such a thing as "pre-destined health" based on the time and year in which we were born?

For obesity risk, a new study found that year of birth may indeed influence one's chances of becoming obese. The research has shown a link between a variant in the FTO gene and its impact on obesity risk based on year of birth. The FTO gene variant is associated with obesity risk, according to a previous study.  

The study conducted by researchers from the Massachusetts General Hospital (MGH) Department of Psychiatry found that those born after 1942 are more likely to have higher obesity risk as the FTO gene variant is more likely to have an effect on post-1942 people. The findings revealed that obesity risk increases as the year of birth advances.

The researchers used data from the Framingham Offspring Study following the children of participants from a long-term study that collected data from 1971-2008. Participants' age ranged from 27 to 63 during those times. The researchers looked at the participants' body mass index (BMI), which was measured eight times during the study period, and their FTO gene variants.

The study saw no correlation between the FTO gene variant and BMI for people born before 1942. However, a stronger correlation was seen in people born after 1942.

The study's lead author Dr. James Niels Rosenquist of the MGH Department of Psychiatry said, "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. These results - to our knowledge the first of their kind - suggest that this and perhaps other correlations between gene variants and physical traits may vary significantly depending on when individuals were born, even for those born into the same families."

The research did not identify the environmental differences that might have had an impact in the observed change in association. The researchers theorized the latter generations' reliance on technology as a contributor to the increased obesity risk as less physical labor is caused by some technological advancement. Another contributor, as hypothesized by the researchers, is the availability of high-calorie processed foods.  

"We know that environment plays a huge role in the expression of genes, and the fact that our effect can be seen even among siblings born during different years implies that global environmental factors such as trends in food products and workplace activity, not just those found within families, may impact genetic traits," according to Rosenquist.

The findings of the research were published in the Proceedings of the National Academy of Sciences.