Researchers from the University of Exeter in England analyzed the data of 120,000 participants aged 40 to 70 years and evaluated their sleep and exercise habits. The researchers gathered information on the subjects' total physical activity, sleep duration, and sleep efficiency. Then, they calculated a genetic risk score for every individual derived from 76 common variants recognized to be linked with a high risk of obesity, evaluated in the context of the data and the individuals' body mass indices (BMIs).
“We wanted to find out if obesity-related genes and activity level have an interactive effect on obesity,” said Andrew Wood, one of the authors of the study.
The findings showed the greatest evidence to date of a modest gene-activity interaction.
Results revealed that those who had poor quality of sleep – waking up often or sleeping restlessly – had higher BMIs than those who had good sleep quality. (Related: Obesity and Insomnia: Sleep Loss is Linked to Weight Gain.)
For a person with an average height of 5.6 feet or 1.73 m and also has 10 genetic variants related to obesity, that genetic risk is responsible for a 7.9 lbs or 3.6 kg increase in weight among those who exercised less, while those who were more physically active accounted for 6.2 lbs or 2.8 kg increase in weight.
Wood likened the effect of being at genetic risk and physically inactive at the same time to a “double whammy” effect.
The findings of the study support previous studies that have suggested that low levels of physical activity and sleep heightened the genetic risk of obesity, according to the researchers. Compared to past studies, the study used objective measures to conduct the study. Frayling said that physical activity and sleep patterns could not be measured accurately until recently. He also warned that previous research often relied subjective data which were based on diaries or self-report.
“But our results emphasize the importance of using objective measures and negative control phenotypes to test the specificity of gene-activity interactions,” Timothy Frayling said.
“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.” he added.
Frayling also said that in future research, they may have the “scope to personalize obesity interventions.” Future investigation will focus on whether this interaction between genetics and physical activity are different between men and women. Moreover, it will analyze the influence of patterns of activity, such as if the effect of a consistent level of moderate activity is different or not.
The study was presented at the American Society of Human Genetics annual meeting in Orlando, Florida.
Fast facts on obesity
The number of obese people globally has almost tripled since 1975. Records from the World Health Organization (WHO) show that at least 1.9 billion adults were overweight in 2016, and more than 650 million of these were obese.
In the U.S., over one-third or 36.6 percent of Americans are obese, according to the Centers for Disease Control and Prevention.
One of the common causes of obesity worldwide is the excessive intake of energy-dense foods that contain a lot of fat. Another cause is the increase of physical inactivity because of the growing trend of sedentary lifestyle in people, because of work, changing modes of transportation, and developing urbanization.
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