Certain genes are associated with weight gain, making some people more susceptible to obesity. New research finds that for these individuals, abnormal sleep patterns can exacerbate the problem.
The study found that people genetically predisposed to obesity whose sleep duration was too long or too short weighed more than those who slept for the recommended 7-9 hours each night.
Daytime napping and shift work were also linked to a heavier weight for those at high genetic risk for obesity.
The research findings were recently published in the American Journal of Clinical Nutrition.
Obesity is now a major public health concern in the United States, affecting more than 1 in 3 adults and 1 in 6 children and adolescents.
Studies have shown that obesity can run in families, and researchers have uncovered numerous genes that can increase a person's susceptibility to weight gain.
For this latest research, study co-author Dr. Jason Gill - from the Institute of Cardiovascular and Medical Sciences at the University of Glasgow in the United Kingdom - and colleagues assessed the effect of poor sleep habits on the weight of individuals at high genetic risk for obesity.
Excess weight more likely with poor sleep habits
The team analyzed the data of 119,859 adults aged between 37 and 73 who were a part of UK Biobank - a national health resource that holds the health data of around 500,000 adults from the U.K.
Specifically, the researchers looked at participants' genetic risk for obesity, as well as self-reported data on average sleep duration, daytime napping, and whether their employment involved shift work.
The body mass index (BMI) and waist circumference of each participant were also assessed.
Among adults who had high genetic risk of obesity, researchers found that those who slept for under 7 hours each night were around 2 kilograms heavier than those who slept for 7-9 hours, while adults who slept for more than 9 hours per night were around 4 kilograms heavier.
Adults who worked shifts or took naps during the day were also more likely to carry excess weight if they had a high genetic obesity risk, compared with those who did not work shifts or take daytime naps.
However, among people with a low genetic risk for obesity, abnormal sleep patterns did not appear have a significant impact on weight. "[...] these people appear to be able to 'get away' with poorer sleep habits to some extent," says Dr. Gill.
The team's findings remained after accounting for diet, sociodemographic factors, and health problems.
Overall, the researchers believe that their findings highlight the importance of maintaining a healthy lifestyle, particularly for those who are genetically predisposed for weight gain.
"It appears that people with high genetic risk for obesity need to take more care about lifestyle factors to maintain a healthy bodyweight. Our data suggest that sleep is another factor which needs to be considered, alongside diet and physical activity."
Study co-author Dr. Carlos Celis-Morales, BHF Cardiovascular Research Centre at Glasgow