How a "fat gene" may influence your weight

Posted: December 31, 2014 at 4:51 am

The year in which you're born might affect the activity of a gene that could raise your odds for obesity, a new study finds.

Members of families who share an obesity-prone mutation of the FTO gene are more likely to carry extra weight if they were born after 1942, the researchers found.

"You could have a family where your father might be born in 1920 and you were born after 1942, and you look exactly like him, and only on the basis of the food and environment around you, you will have a higher BMI than your father," said lead author Dr. James Niels Rosenquist, an instructor at Harvard Medical School and psychiatrist with Massachusetts General Hospital in Boston. BMI (body mass index) is a standard measurement of weight and height.

According to the researchers, prior studies have linked variations in the FTO gene to a propensity toward overweight and obesity. For example, federal researchers earlier this year reported that people with mutated FTO genes are more likely to eat high-calorie or fatty foods as they age, compared to people without the mutations.

While the study couldn't prove cause-and-effect, the findings suggest that changes in American culture may be boosting the obesity threat tied to the FTO gene mutation.

To take a multi-generational look at obesity risk, the researchers relied on the Framingham Heart Study, a decades-old study of more than 10,000 parents, children and even grandchildren hailing from the town of Framingham, Mass.

About two-thirds of the more than 5,100 children born to the original Framingham participants have had their DNA sequenced. This allowed the research team to determine which families carried the obesity-prone versions of the FTO gene.

The researchers compared people's genes to changes in BMI measurements taken over time, and then compared that to the years participants were born.

Rosenquist's team found no link between the FTO gene and obesity for people born prior to 1942. However, they found a very strong link between the gene and obesity in those born after 1942 -- a link twice as strong as reported in previous studies.

Dr. Mitchell Roslin is chief of obesity surgery at Lenox Hill Hospital in New York City. He said that science is beginning to show that genes alone may not determine a person's fate. Instead, genes often appear to respond to outside influences, so there's a combination of environment and genetics at play.

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How a "fat gene" may influence your weight

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