Not All Forms of Exercise Cut Obesity Risk in Genetically Predisposed People, Data Show
Exercises such as regular jogging, mountain climbing, and walking can reduce the effects of genetic predisposition to obesity, new research suggests. However, the genetic effects on obesity do not seem to be influenced by other exercises, such as cycling, stretching, or swimming.
The data were published in the journal PLOS Genetics in a paper titled, “Performing different kinds of physical exercise differentially attenuates the genetic effects on obesity measures: Evidence from 18,424 Taiwan Biobank participants.”
It’s well-established that both genetic and lifestyle factors can affect how a person puts on weight. Regular exercise is well-supported as a way to reduce body fat, but “exercising” is a broad term that can refer to many different activities. What kinds of exercise are best for reducing the chances of obesity among people who are genetically predisposed to it?
To find out, researchers looked at data for 18,424 unrelated people in the Taiwan Biobank, which collects genetic, lifestyle, and health information from people living in Taiwan. The participants were ages 30–70, with an even mix of men and women.
Using results of previous studies in combination with new analyses of this dataset, the researchers identified a panel of genetic variants linked to higher body mass index (BMI, a measurement of weight in relation to height).
Using this panel, they created a BMI genetic risk score for obesity and used it to stratify patients. They then used statistical models to determine what effect, if any, 18 different kinds of exercise had on genetic predisposition to obesity.
Because BMI isn’t a very clinically useful measurement — it doesn’t take into account factors such as fat distribution or muscle mass, which have significant effects on health — the researchers didn’t just look at the effect of exercise and genetics on BMI. They also examined four other measurements of obesity: body fat percentage (BFP), waist circumference, hip circumference (HC), and waist-to-hip ratio.
Overall, sex was the most powerful predictor of obesity; males had significantly higher average values in all measurements but BFP. For all five metrics, education level was associated with lower measurements, which mirrors findings from previous studies.
Of the participants, 7,652 (41.5%) reported regular exercise of some kind. In general, exercise of any kind had a significant effect on genetics-mediated obesity: For every one standard deviation increase in BMI genetic risk score, people who exercised had an average 0.43 kg/m2 lower BMI and 0.62% lower BFP compared to those who did not exercise.
Put less technically, on average, people with a similarly high genetic risk for obesity were likelier to be less heavy if they exercised.
As far as the different kinds of exercise, jogging, mountain climbing, walking, exercise walking, and international standard (ballroom) dancing were all associated with reducing BMI. Yoga was also linked with reducing BMI, but only among people who performed longer sessions.
Jogging was the only specific exercise with a significant effect on other measurements of body fat; it significantly reduced BFP and HC as well.
The researchers noted that there were relatively few people who reported participating in some of the types of exercise analyzed, namely weight training, badminton, table tennis, basketball, and tennis. As such, it’s unlikely that a statistically significant effect could be detected if it exists, so more research on these particular activities may be required.
Cycling, stretching exercise, qigong, swimming, and playing Dance Dance Revolution — which the researchers described in their paper as “a computer game based on dancing with music videos” — all had at least as many participants as yoga did, but none came close to a statistically significant effect, which suggests that these types of exercise might not be as effective for ameliorating genetic predisposition to obesity.
It’s not completely clear why this would be, though the researchers offered some speculation: for example, swimming in cold water might stimulate appetite, and Dance Dance Revolution is “not as formal as international standard dancing.” Future research may help clarify which types of exercise are truly beneficial for people who are genetically at risk of obesity.