According to a recent study, certain obese individuals may find it difficult to shed those extra pounds due to genetic factors. The study published in ‘Jama Network Open’ suggests that the key to reducing the risk of obesity may lie in tailored physical activity recommendations that incorporate genetic background into account.

      The utilization of activity, clinical, and genetic data from the All of Us Research Program (AoURP) to explore the association of genetic risk of higher body mass index (BMI) with the level of physical activity needed to reduce incident obesity were considered for the study. In this US population–based retrospective cohort study, participants were enrolled in the AoURP between May 1, 2018, and July 1, 2022. Enrollees in the AoURP who were of European ancestry, owned a personal activity tracking device, and did not have obesity up to 6 months into activity tracking were included in the analysis. Physical activity expressed as daily step counts and a polygenic risk score (PRS) for BMI, calculated as weight in kilograms divided by height in meters squared.

      A total of 3124 participants met inclusion criteria. The median age of the 3051 participants for whom data were available was 52.7 (IQR, 36.4-62.8) years, and 2216 (73%) of them were female. After tracking their own activities for a median of 5.4 (IQR, 3.4-7.0) years, the cohort consisting of 3124 individuals walked a median of 8326 (IQR, 6499-10 389) steps/d. Over the study period, the incidence of obesity increased in the lowest and highest PRS quartiles, from 13% (101 of 781) to 43% (335 of 781), respectively (P = 1.0 x 10−20). When comparing the 75th and 25th percentiles, respectively, the BMI PRS showed an 81% rise in obesity risk (P = 3.57 × 10−20) while the mean step count showed a 43% reduction in obesity risk (P = 5.30 × 10−12). To have a comparable risk of obesity, people with a PRS in the 75th percentile would need to walk an additional 2280 (95% CI, 1680-3310) steps per day on average (11,020 total) than people in the 50th percentile. Those at the 75th percentile with a baseline BMI of 22 would need to walk an extra 3460 steps per day; those at the 24th percentile would need to walk an extra 4430 steps per day; those at the 26th percentile would need to walk an extra 5380 steps per day; and those at the 28th percentile would need to walk an extra 6350 steps per day in order to have an obesity risk that is comparable to that of people at the 25th percentile of PRS.

      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 novel and important from this study is that the researchers were able to quantify the amount of activity needed to reduce the risk.