A lack of exercise and a poor night’s sleep are a ‘double whammy’ to those prone to piling on the pounds, a study suggests.
In what is believed to be the strongest evidence to date, scientists discovered that both intensify the effects of genetic risk factors for obesity.
Not exercising enough equates to weight gain of 1.7lbs (800g) for adults deemed at risk. Similar results were recorded for those who had restless sleep.
The findings, derived from assessing 120,000 adults, ’emphasise the importance’ of keeping active in those genetically predisposed to becoming obese.
In what is believed to be the strongest evidence to date, scientists discovered that both intensify the effects of genetic risk factors for obesity
University of Exeter researchers believe their findings may offer hope of personalised obesity interventions.
‘Double whammy’ effect
Dr Andrew Wood, involved in the study, said: ‘We wanted to find out if obesity-related genes and activity level have an interactive effect on obesity risk.
He described this as like a ‘double whammy’ effect of being both at genetic risk and physically inactive, beyond the additive effect of these factors’.
Professor Timothy Frayling, also involved in the study, said until recently, physical activity and sleep patterns could not be measured accurately.
He warned that they often relied on diaries and self-reports, which don’t always paint the most accurate results.
How was the study carried out?
Using data of 120,000 individuals between the ages of 40 and 70, they tested their sleep and exercise hypothesis.
Data measuring their total physical activity, bouted activity, sleep duration and sleep efficiency was collected.
They computed a genetic risk score for each participant based on 76 common variants known to be associated with elevated risk of obesity.
This was analysed in the context of the data and the participants’ BMIs. Results found the strongest evidence to date of a modest gene-activity interaction.
What did they find?
For example, for a person of average height (5ft 6in or 1.73m) with 10 genetic variants associated with obesity, that genetic risk accounted for a 7.9lbs (3.6kg) increase in weight among those who were less physically active but just 6.2lbs (2.8kg) among those who were more active.
Results were similar in analyses of sleep patterns; among participants with some genetic risk of obesity.
Those who woke up frequently or slept more restlessly had higher BMIs than those who slept more efficiently.
Professor Frayling said: ‘Our results are consistent with previous studies suggesting that low levels of physical activity and sleep accentuate the genetic risk of obesity.
‘But our results emphasise the importance of using objective measures and negative control phenotypes to test the specificity of gene-activity interactions.
‘We hope these findings will inform clinicians who help people lose or maintain their weight.
‘Ultimately, with further research, we may have the scope to personalise obesity interventions.’
Further research required
He added that the findings could ‘contribute to the understanding that obesity is complex and its prevention may look different for different people’.
Future research will investigate whether this interaction between genetics and physical activity differs between men and women.
It will also study the effects of patterns of activity – for example, whether a consistent level of moderate activity has a different effect.
The results were presented at the American Society of Human Genetics annual meeting in Orlando, Florida.