Genes Only Partly To Blame For Obesity

3D DNA strand illustrationIf you have trouble keeping slim, don’t put all the blame on your DNA.

People carrying so-called “obesity” genes tend to gain more weight if they don’t work out or don’t get enough sleep, said Timothy Frayling, a professor with the University of Exeter Medical School in England.

“You can’t change your genes — but they only explain part of your weight,” Frayling said. This means that even people genetically inclined to pile on pounds can curb it by eating right and exercising.

Frayling and his fellow researchers tracked physical activity and sleep patterns for about 85,000 people in England, aged 40 to 70. The participants wore accelerometers that allowed researchers to estimate their amount of exercise and quality of sleep.

The team also computed a genetic risk score for each person based on 76 common variants known to be associated with increased risk for obesity.

Genetics accounted for some, but not all, of a person’s obesity risk, the researchers concluded.

For example, a person of average height who had 10 genetic risk factors for obesity gained an average of 8 pounds during the course of their life if they tended to be couch potatoes, but only about 6 pounds if they were more physically active, the study authors said.

The results were similar regarding sleeplessness. People with some genetic risk for obesity tended to have a higher body mass index (BMI) if they woke frequently or slept more restlessly, the study findings showed. BMI is a measurement of body fat based on height and weight.

“For public health and diet and exercise interventions, our study suggests there will be ‘bigger bang for the buck’ by focusing limited resources on people who are most susceptible due to their genes and their lifestyles,” Frayling said.

Obesity experts said the study results make sense, given what’s known about the factors that contribute to excess weight.