Research has shown that people who don’t get enough sleep can disrupt the activity of their genes, and are at a higher risk of developing certain diseases. It’s also well known that a lack of physical activity can cause obesity. New work has confirmed that low amounts of exercise and inefficient sleep can amplify genetic factors that increase the risk of obesity. An extensive study by researchers who investigate body mass index and type 2 diabetes has been presented at this year’s annual meeting of the American Society of Human Genetics (ASHG).
Timothy Frayling, a Professor at the University of Exeter Medical School, and postdoctoral researcher Andrew Wood performed the work. Frayling explained that in the past it was challenging to measure the influence of genetic risk factors, aspects of a person’s environment and their lifestyle in systematic ways. "Until recently, physical activity and sleep patterns could not be measured with as much precision as genetic variants, and we relied on diaries or self-report, which can be very subjective," Dr. Frayling noted.
This new work, however, has used a sizeable genetic dataset comprised of about 85,000 UK Biobank participants from 40 to 70 years of age, and information obtained from wrist accelerometers, making it quantifiable and more objective.
"We wanted to find out if obesity-related genes and activity level have an interactive effect on obesity risk - if there is a 'double whammy' effect of being both at genetic risk and physically inactive, beyond the additive effect of these factors," said Dr. Wood. For each participant, a genetic risk score was calculated based on 76 common variants that have been linked to an elevated risk of obesity. The researchers then analyzed the participant’s scores in the context of their BMI and accelerometer data.
The investigators have now established strong evidence of interactions between gene variants and physical activity. If people of average height carry ten genetic variants that have been associated with obesity, the genetic risk translates to a 3.8-kilogram weight increase in people that are not physically active and a 2.8-kilogram increase in more active people.
Sleep patterns had a similar influence. In those with a genetic risk for obesity, when sleep was more disrupted (whether by waking frequently or sleeping restlessly), BMI was higher compared to those who slept well.
Next, the scientists want to know whether the association between genetic factors and physical activity is different in women and men. They are also assessing how patterns influence activity. For example, a consistent amount of moderate activity might have different effects than low levels of activity interspersed with short periods of vigorous work.
"We hope these findings will inform clinicians who help people lose or maintain their weight and contribute to the understanding that obesity is complex and its prevention may look different for different people," said Dr. Frayling. "Ultimately, with further research, we may have the scope to personalize obesity interventions," he concluded.
There is still debate about how much genes contribute to obesity. Learn a little more from the short video above from the University of Michigan.
Sources: AAAS/Eurekalert! Via ASHG