Your Year of Birth May Determine Risk of Obesity

We've known about the common causes of obesity for long. Lifestyle, eating habits and another one that is blamed quite often is an individual's genetic disposition. According to science, there is a particular gene that is primarily associated with obesity. A previous study explained that obesity is linked to the impact of a variant in the FTO gene. However, scientists have now discovered that the impact of a gene associated with obesity, largely depends on the birth year of an individual! Scientists are of the opinion that the co-relation between this gene variant and a person's BMI (body mass index) becomes stronger as the year of birth progresses. By this they mean that a person who was born earlier may have a weaker co-relation between the gene variant and BMI. "Looking at the 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 James Niels Rosenquist, of the Massachusetts General Hospital (MGH) Department of Psychiatry, lead author of the report. "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," said Rosenquist. Surprisingly, no correlation was found between the obesity-risk variant and BMI in those who were born before 1942. For others who were born after 1942, the correlation was twice as strong as reported in previous studies. Some of the previous studies of similar nature looked at the interactions between genes and the environment in groups born during a particular span of years. This would have excluded any analysis of changes in the larger environment taking place over time. To overcome this problem, researchers analysed human data from the year 1971 to 2008. The data was accumulated from those who participated in the Framingham Offspring Study - which follows the children of participants in the original study.Who is to blame? The study was not able to identify the environmental differences that combine with the FTO variant to increase the risk of obesity, However, the authors noted that post-World War II factors such as increased reliance on technology, lack of physical labour and the availability of high-calorie processed foods are likely contributors. Over the years these lifestyle changes have come to affect our biological condition and therefore have made us susceptible to many such ailments that were not common in earlier years. "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," said Rosenquist. Inputs from PTI