Obesity Prevalence, BMI Decreased in US for First Time in a Decade

The year 2023 saw the first decrease in both body mass index (BMI) and the prevalence of obesity in the US in more than a decade, new data show, concurrent with antiobesity medications such as semaglutide becoming more widely available to patients. According to the research letter published in JAMA Health Forum,¹ the biggest decrease was found in the southern US.

The increased prevalence of obesity in the US has been a public health concern as obesity can be a leading cause of other conditions, such as diabetes and cardiovascular disease.² Antiobesity medications, such as semaglutide, have become more easily accessible to patients who are interested, leading to increased demand for these medications. Although the usage of weight-loss drugs has increased, the immediate result of this increase has not been evaluated. This study aimed to assess how obesity and BMI changed in adults 18 years and older between January 1, 2013, and December 31, 2023.

The Optum Market Clarity Data, containing linked medical and insurance claims and electronic health records, were used for the cross-sectional study. All data were deidentified for the purposes of the study. Data were included from US medical groups that contributed continuously to the database between 2013 and 2023. Any adult with electronic health record data was included. The highest measurement of BMI was extracted for all patients along with race, ethnicity, age, and geographic region of outpatient visits.

Calculations per year and by demographic strata were conducted to calculate mean population BMI and the percentage of adults with obesity. The World Health Organization’s measurements and projections for obesity were compared with the obesity estimates for this study.

There were 16,743,822 adults who contributed 47,939,382 measurements of BMI and were included in this study. Most of the participants were women (51.3%) and aged 26 to 75 years (78.4%). The mean (SD) BMI of the included participants rose between 2013 and 2021 (29.65 [1.99] to 30.23 [2.04]). Mean BMI was stable in 2022 without a major increase (30.24 [2.04]) before a slight decrease was found in 2023 (30.21 [1.99]). A sensitivity analysis was also found to corroborate the decline in prevalence of obesity (46.2% in 2021 vs 45.6% in 2023).

Individuals aged 66 to 75 years and women were the subgroups who saw a decrease in obesity prevalence in the South. Despite the decrease, individuals in the South region had the second-highest prevalence of obesity in the country, behind only the Midwest. The South had the highest dispensing of glucagon-like peptide 1 receptor agonist (GLP-1 RA) drugs at 6.0%, compared with 5.1% in the Midwest, 4.4% in the Northeast, and 3.4% in the West.

“However, dispensing does not necessarily mean uptake, and the South also experienced disproportionately high COVID-19 mortality among individuals with obesity,” the authors noted.

There were some limitations to this study. The researchers noted that BMI and obesity are not perfect measures for weight, and future studies should focus on different body types. The potential causes of the shifts in prevalence should also be looked into to determine whether the shift came from increased use of GLP-1 RAs or from changes in behavior or demographics. Selection bias is possible due to BMI being collected during visits to the doctor.

The researchers concluded that the reduction of obesity in 2023 is a positive sign that the prevalence of obesity in the US may be on the decline.

References

1. Rader B, Hazan R, Brownstein JS. Changes in adult obesity trends in the US. JAMA Health Forum. 2024;5(12):e243685. doi:10.1001/jamahealthforum.2024.3685
2. Mayo Clinic Staff. Obesity. Mayo Clinic. July 22, 2023. Accessed December 12, 2024. https://www.mayoclinic.org/diseases-conditions/obesity/symptoms-causes/syc-20375742