Obesity and BMI decrease in the US for the first time in a decade

For the first time in over 10 years, the United States has seen a slight decline in obesity prevalence and average body mass index (BMI). Researchers, in a study published in JAMA Health Forum, tracked trends from 2013 to 2023 and observed a modest reduction in both metrics in 2023, with the most significant changes occurring in the South.

Obesity in the US has been a steadily rising concern for decades, even exacerbated during the COVID-19 pandemic. While some forecasts suggest this trend may level off, others anticipate it could continue unabated. The landscape has become more complex with post-pandemic shifts in lifestyle and the growing use of weight-loss medications, such as GLP-1 receptor agonists (GLP-1RAs), which mimic a natural hormone to regulate appetite and blood sugar levels.

Medications like semaglutide have shown promise in managing obesity and type 2 diabetes, adding a new layer of potential influence on national obesity rates. The study analysed data from over 16 million individuals between 2013 and 2023, focusing on annual BMI measurements and demographic variables such as age, region, and race. On average, BMI increased each year from 2013 to 2021, peaking at 30.24 before stabilizing in 2022 and slightly decreasing to 30.21 in 2023. Obesity prevalence followed a similar trend, with the percentage of adults with a BMI of 30 or greater falling from 46.2 per cent in 2021 to 45.6 per cent in 2023.

Notably, the South, where GLP-1RA dispensing rates were the highest, experienced the most pronounced declines. However, the correlation between high medication availability and obesity reduction is not straightforward, as these medications may not be widely accessible to all populations. The South also bore the brunt of pandemic-related mortality among obese individuals, complicating the interpretation of the results.

The study highlights limitations, including selection bias and the reliance on BMI as a primary metric for obesity. BMI does not fully capture body fat composition, and data derived from medical visits may not reflect the general population. Still, the observed trends align closely with World Health Organization (WHO) data, adding weight to the findings.

Researchers caution that the decline in obesity prevalence should be viewed as a preliminary shift rather than a definitive reversal of decades-long trends. Future studies will need to explore more precise measures of body composition and investigate factors such as medication accessibility, demographic changes, and post-pandemic behavior shifts.

While the reasons behind the decline remain multifaceted, this development represents a hopeful signal in the ongoing battle against obesity, a pervasive public health issue in the US.