NEW YORK – Regular exercise, particularly jogging, can dial down obesity risk in individuals who are genetically prone to the condition, according to a new study of Han Chinese adults that was published online today in PLOS Genetics.
"The genetic effects on obesity measures can be decreased to various extents by performing different kinds of exercise," senior and co-corresponding author Po-Hsiu Kuo, a researcher at the College of Public Health at National Taiwan University, and her co-authors wrote, emphasizing that "benefits of regular physical exercise, especially jogging, are more impactful in subjects who are more predisposed to obesity."
Kuo and her team tapped into the Taiwan Biobank, using SNP profiles for more than 18,400 Han Chinese individuals to come up with genetic risk scores (GRS) for five measures of obesity: body mass index (BMI), body fat percentage, waist circumference, hip circumference, and waist-to-hip ratio. From there, they attempted to tease out interactions between the GRS and self-reported participation in up to 18 kinds of exercise — from weight training or walking to playing badminton or boogying down to the computer game Dance Dance Revolution.
While several exercises did not seem to mitigate genetic susceptibility to any of the obesity measures considered, the investigators saw modifying effects for half a dozen types of exercise. Physical activities such as yoga, walking, and mountain climbing could amend genetic susceptibility to at least one obesity measurement. But it was jogging that dimmed genetic risk for most of the obesity measurements, even when done about as often as other forms of exercise, and for similar stretches of time.
The work followed from past research, which had suggested regular workouts can dull the effects of obesity-related genetic factors. To dig into the specific kinds of exercise that might modify genetic predisposition to obesity, the researchers dialed into Taiwan Biobank data for 18,424 Han Chinese adults genotyped at almost 647,000 SNPs with Affymetrix SNP arrays.
Along with participants' height and weight, the Biobank provided insights into physical activity. More than 7,650 individuals said they exercised regularly and provided information on how often they worked out, as well as their favored exercise types. Almost 10,800 individuals said they did not exercise regularly.
Using genetic imputation and clues from 97 SNPs implicated in BMI in other populations, the team estimated the proportion of variation in each obesity measurement that these polymorphisms could explain in Taiwan Biobank participants before developing population-specific, internally weighted GRSs.
"Because there have been no large genome-wide association studies on obesity for Han Chinese," the authors explained, "we used the [Taiwan Biobank] internal weights to construct genetic risk scores for each obesity measure, and then [tested] the significance of GRS-by-exercise interactions."
Generally speaking, the researchers' analyses suggested regular physical activity could attenuate genetic susceptibility to all but one of the obesity measurements considered, waist-to-hip ratio. Even so, they concluded, the specific GRS-exercise interactions did vary somewhat depending on the type of exercise analyzed.
While exercises such as mountain climbing, exercise walking, yoga, or international standard dance seemed to mitigate the genetic effects of at least one obesity measurement, for example, the team concluded that jogging had the most pronounced and widespread influence over the obesity-related GRSs.
"Across all [five] obesity measures, jogging consistently presented the most significant interactions with GRSs," the authors explained, noting that "the effects of GRSs on [BMI, body fat percentage, waist circumference, and hip circumference] were smaller in joggers than in non-joggers."