Physical Activity May Counteract Effects of Obesity Genes, Study Says

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by Joana Carvalho |

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exercise, obesity

A lifestyle of high physical activity and low sedentary habits may counterbalance the genetic predisposition some individuals have for developing obesity, a study says.

The findings of the study, “Do physical activity, commuting mode, cardiorespiratory fitness and sedentary behaviours modify the genetic predisposition to higher BMI? Findings from a UK Biobank study,” were published in the International Journal of Obesity.

Obesity is a highly variable disorder resulting from a combination of genetic, environmental, and lifestyle factors. About 40%–70% of its variation is believed to be due to individual differences in genetic backgrounds.

The last 30 years has seen a steady increase in the number of individuals affected by obesity, which has been mostly attributed to changes in people’s lifestyle, including ingestion of high-fat foods, low physical activity, and high sedentary behaviours.

In this study, a group of researchers from the University of Glasgow set out to investigate if the relationship between genetic risk factors of obesity and body mass index (BMI) may be affected by the level of physical activity, fitness, and sedentary behaviors.

Their “findings emphasise that, although obesity is partly genetically determined, lifestyle can play a major role,” the researchers stated. “Indeed, our findings suggest that the potential benefits of favourable lifestyle factors may act more strongly in individuals with higher genetic propensity to obesity.”

The researchers analyzed data from a group of 310,652 individuals who were more or less genetically predisposed to develop obesity (based on information from 93 different genetic variations that had been previously associated with the disorder), which had been stored at the U.K. Biobank between April 2007 and December 2010.

BMI, level of physical activity, cardiorespiratory fitness, walking pace, and sedentarism were collected for all study subjects. Statistical analyses were used to examine the relationship between genetic risk factors for obesity and BMI, based on the individuals’ level of physical activity, fitness, and sedentary behavior.

From the 310,652 individuals whose records were analyzed in the cross-sectional study, 66.8% were considered overweight or obese based on their BMIs, and 33.0% had central obesity based on their waist circumferences.

As expected, genetic risk factors for obesity were strongly correlated with BMI.

The researchers found the relationship between genetic risk factors for obesity and BMI was also affected by the individuals’ level of physical activity. For a fixed increase in the genetic risk score for obesity, patients with low levels of physical activity had an increase in their BMI by an average 0.58 kg/m2, while that of those who exercised regularly was 0.33 kg/m2 higher.

Similar findings were observed for:

  • Cardiorespiratory fitness (BMI increase of 0.72 kg/m2 for unfit individuals and 0.36 kg/m2 for fit individuals)
  • Walking pace (BMI increase of 0.91 kg/m2 for slow walkers and 0.38 kg/m2 for fast walkers)
  • Sedentary behavior (BMI increase of 0.64 kg/m2 for high sedentary individuals and 0.48 kg/m2 for low sedentary individuals);
  • Time spent watching TV (BMI increase of 0.62 kg/m2 for long-time TV viewers and 0.47 kg/m2 for short-time TV viewers);
  • Time spent playing videogames (BMI increase of 0.69 kg/m2 for long-time gamers and 0.52 kg/m2 for short-time gamers).

The use of a car or bike, or public transportation did not have a significant impact on the relationship between genetic risk factors of obesity and BMI.

“Our results show that higher levels of [physical activity] and fitness attenuate, while high levels of sedentary behaviors accentuate, the strength of the association between genetic predisposition to obesity with BMI,” the researchers wrote.

“These findings are relevant for public health and suggest that promotion of increased [physical activity] and reduced sedentary behaviors, alongside with other healthy lifestyle behaviors, particularly in those who are genetically susceptible to higher BMI, could be an important strategy for addressing the current obesity epidemic and disease burden,” they added.

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