The South showed the most significant decrease alongside high GLP-1RA dispensing rates, though uptake and other health factors remain complex

In a recent article published in JAMA Health Forum, researchers assessed trends in obesity and body mass index (BMI) across American adults between 2013 and 2023.

Their findings indicate that BMI and the prevalence of obesity in the United States decreased for the first time in 10 years in 2023, particularly in southern states.

Background

Obesity prevalence across the United States has been rising steadily for decades, a trend that persisted even during the coronavirus disease 2019 (COVID-19) pandemic. While certain long-term projections suggest that this upward trend will continue unabated, other forecasts predict it may level off.

However, as the nation moves beyond the pandemic and adapts to new health conditions, the situation becomes more complex.

The increasing availability and use of weight loss medications, such as semaglutide, a glucagon-like peptide-1 receptor agonist (GLP-1RA), add another layer of uncertainty to predictions about obesity rates in the near future.

GLP-1 is a hormone produced in the gut that plays a critical role in regulating appetite and blood sugar levels. GLP-1RAs are a class of medications that mimic the action of this hormone and have been used to treat type 2 diabetes and obesity, helping lower blood sugar by stimulating the secretion of insulin, slowing gastric emptying, and reducing appetite.

These factors underscore the need for close monitoring and further research to understand better the potential impacts of post-pandemic lifestyle changes and medical interventions on obesity prevalence.

About the study

Researchers analyzed deidentified data linking insurance and medical claims with electronic health records. They included data from all groups in the United States that contributed continuously to the database from 2013 to 2023.

The analysis focused on American adults regardless of their claims data or insurance status. For non-pregnant adults, the highest BMI was recorded each year, along with demographic details such as geographic region, age, and ethnicity or race (White, Hispanic, Black, Asian, or other).

Annual average BMI and obesity prevalence (defined as a BMI greater than or equal to 30) were estimated overall and by different demographic groups. These measures were adjusted to align with the 2020 US census demographics.

Researchers compared the results with data from the World Health Organization (WHO) from 2013 to 2015 and projections for the period 2016 to 2022. Sensitivity analyses were conducted using unweighted data.

Findings

The study included 16,743,822 unique individuals over 18, 78.4% of whom were aged 26 to 75 years, and 51.3% of whom were female, contributing 47,939,382 BMI measurements. On average, the population BMI increased each year from 29.65 in 2013 to 30.23 in 2021, leveled off in 2022 at 30.24, and slightly decreased in 2023 to 30.21.

A similar trend was observed in the percentage of adults with a BMI greater than or equal to 30, with obesity trends in the study data closely matching WHO data until 2021.

In 2023, obesity prevalence declined in certain groups, including individuals in the South, those aged between 66 and 75, and females. Sensitivity analysis with unweighted data also showed a decrease in obesity prevalence (46.2% in 2021, 46.0% in 2022, and 45.6% in 2023).

Among 10,625,745 adults with insurance claims in 2023, regional differences in GLP-1RA provision were noted, with the highest use (6%) in the South and the lowest (3.4%) in the West.

Conclusions

Researchers found indications that for the first time in over a decade, obesity prevalence and BMI in the United States declined in 2023. This reduction was particularly pronounced in the South; this region also had the highest per capita dispensing rate of GLP-1RAs.

However, it is important to note that high dispensing rates do not necessarily equate to widespread usage. The South also faced disproportionately high mortality rates during the COVID-19 pandemic among obese individuals.

While BMI and obesity prevalence are widely used indicators, they are imperfect measures of body fat (adiposity). Future research should explore more accurate body composition metrics and investigate potential factors driving these changes. These factors could include the increased availability of GLP-1RAs (such as through uninsured purchases) and shifts in demographics or behaviors influenced by the pandemic.

This study has limitations, including potential selection bias and changes in the study population. For example, BMI measurements taken during medical visits might not fully represent the general population. They could be a reason for a slightly higher prevalence of obesity observed in the dataset. However, the study’s trends are closely aligned with authoritative data from the WHO, lending credibility to the findings.

Despite its limitations, the observed decrease in the prevalence of obesity represents a promising shift, marking a potential reversal of the long-standing upward trend in obesity—a persistent public health challenge.