Year of Birth a Factor in Obesity, say Researchers

A person's year of birth is related to obesity risk, say researchers. A study done by researchers from Harvard Medical School found that people born before 1942 were less likely to be affected by a gene variant linked to obesity than those born after that year. The risk progressively increases in some with the number of years.

"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 author James Niels Rosenquist from Massachusetts General Hospital (MGH), in a press release. 

Data from the Framingham heart study from 1971 to 2008 was used when the  participants in the study ranged in ages from from 27 to 63. 

The researchers measure the participants' body mass index (BMI) eight times during the study period and the relationship between the FTO gene variants they had inherited.  They found a direct relation between the gene and obesity in people born in the years after the World War.

While there was no correlation between the obesity-risk variant and BMI for those born before 1942, participants born after 1942 were seen to be twice at risk  compared to previous studies. 

Post war technology boom and the availability of high-calorie processed foods  likely contributed to the environmental effects of obesity, the authors noted. 

"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," Rosenquist said. "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."

Obesity rates have tripled in children and adolescents in the last 30 years, according to the Centers for Disease Control and Prevention.
The study appeared in the journal PNAS Early Edition.