Some folks struggling with obesity appear to be hampered by their own genes when it comes to working off those extra pounds, a new study finds.

People with a higher genetic risk of obesity have to exercise more to avoid becoming unhealthily heavy, researchers discovered.

“Genetic background contributes to the amount of physical activity needed to mitigate obesity. The higher the genetic risk, the more steps needed per day,” said senior researcher Douglas Ruderfer, director of the Center for Digital Genomic Medicine at Vanderbilt University Medical Center in Nashville, Tenn.

Because of that, physical activity guidelines might not be so helpful when it comes to maintaining a healthy weight, since individual genetic differences drive how much exercise each person requires, Ruderfer noted.

People instead need to be “active enough to account for their genetic background, or their genetic risk for obesity, regardless of how high that risk might be,” Ruderfer said in a Vanderbilt news release.

For the study, researchers tracked more than 3,100 middle-aged people who weren’t obese and who walked an average 8,300 steps a day for more than five years.

Obesity increased 43% among people with the highest genetic risk scores for obesity, but only by 13% among those with the lowest risk, researchers found.

Results showed those with the highest genetic risk for obesity had to walk an average of 2,280 more steps per day than those with average risk to avoid packing on pounds.

Further, people with high genetic risk and BMIs between 22 and 28 needed to walk an additional 3,460 to 6,350 steps per day to have a risk comparable to folks with the least genetic predisposition to obesity.

Healthy weight BMI runs from 18.5 to 24.9, while overweight runs from 25 to 29.9.

“I think it is intuitive that individuals who have a higher genetic risk of obesity might need to have more physical activity to reduce that risk, but what is new and important from this study is that we were able to put a number on the amount of activity needed to reduce the risk,” said lead researcher Dr. Evan Brittain, an associate professor of cardiovascular medicine at Vanderbilt.

The new study was published March 27 in the journal JAMA Network Open.

Doctors next want to see if people armed with knowledge of their genetic risk can achieve better health and less obesity.

“We would like to test whether knowledge of one’s genetic risk for obesity actually has an impact on their behavior,” Brittain said. “I think these findings could be empowering for patients because the current physical activity guidelines take a one-size-fits-all approach, and what we learned is that depending on your genetic risk, the guidelines may underestimate the amount of activity needed to reduce your risk of obesity.”

One day, doctors might be able to issue specific prescriptions for exercise based on each patient’s genetic profile, Brittain said.

“You can imagine a future in which that data could be integrated with someone’s electronic health record and could form the basis of an individual’s physical activity recommendation from their doctor,” Brittain said. “Most importantly, I would like for patients to know that your genetic risk doesn’t determine your overall risk of obesity, and you can actually overcome that risk by being more active.”

More information

The Harvard T.H. Chan School of Public Health has more on exercise to control weight.

SOURCE: Vanderbilt University, news release, March 27, 2024

Source: HealthDay