People born after 1942 are more likely to be affected by a gene that strongly increases the chance of obesity, a new study suggests.
In previous studies, variations in the FTO gene have been linked to a tendency toward obesity. The new study suggests the gene might be activated by environmental and lifestyle factors – including high-calorie, fatty foods as well as bigger portion sizes since World War II – making it more likely that people will be larger and weigh more than their parents and grandparents.
For the current work, researchers at Harvard Medical School and Massachusetts General Hospital in Boston looked at the suspected link between genetic and environmental factors involved in obesity risk by studying participants in the so-called Framingham Heart Study. The ongoing heart study has followed the health of more than 10,000 people from the Massachusetts town of Framingham for several decades.
The research looked at the body mass index (BMI) – a measure of body fat based on height and weight – of parents, their children and grandchildren.
About two-thirds of the more than 5,000 children born to the study's original participants have had their DNA sequenced, which allowed investigators to identify which families carried the genetic variant making them prone toward weight gain.
Comparing each person's BMI to the year they were born, researchers found no connection between the FTO gene and people born before 1942. However, there was a strong link between the gene and obesity in those born after that year.
Experts say research is beginning to show that having a particular obesity gene alone does not automatically mean someone will become overweight. Rather, the combination of the gene with environmental factors – such as diet and a sedentary lifestyle – appears at fault.
The findings were reported December 29 in the journal Proceedings of the National Academy of Sciences.