Escalating health concerns demand urgent action to combat rising obesity rates.
Study: National-level and state-level prevalence of overweight and obesity among children, adolescents, and adults in the USA, 1990–2021, and forecasts up to 2050. Image Credit: Cynthia A Jackson/Shutterstock.com
In a recent study published in The Lancet, a group of researchers estimated and forecast overweight and obesity trends in the United States of America (USA) (1990-2050) across all ages, guiding health policy and interventions.
Background
The USA faces a severe obesity epidemic, with rising trends causing significant health, economic, and environmental burdens. Obesity contributes to 335,000 deaths and 11.6 million disability-adjusted life-years annually, with direct healthcare costs exceeding $260 billion.
Childhood obesity is particularly alarming, affecting nearly 20% of youth and driving early-onset diseases like diabetes and cardiovascular conditions. Geographical, socioeconomic, and racial disparities exacerbate the issue, influenced by factors like food deserts, lack of recreational spaces, and genetic predispositions.
Monitoring and forecasting obesity trends are critical for effective prevention and tailored interventions. Further research is needed to address disparities and improve policy responses.
About the study
The present study estimated the prevalence of overweight and obesity among children, adolescents, and adults in the USA from 1990 to 2021, with projections to 2050. Overweight and obesity were defined using body mass index (BMI) thresholds, with classifications for children and adolescents based on International Obesity Task Force criteria.
Data were systematically collected from 134 sources, including major US national surveys like the National Health and Nutrition Examination Survey (NHANES) and Behavioral Risk Factor Surveillance System (BRFSS), encompassing self-reported and directly measured heights and weights.
Rigorous quality checks ensured consistency, and bias adjustments were applied to self-reported data using statistical models tailored to age, sex, and time period.
The prevalence estimates were generated using spatiotemporal Gaussian process regression models, incorporating covariates like urbanization, education, and agricultural employment to capture socioeconomic influences.
For projections, a generalized ensemble modeling approach integrated multiple submodels, leveraging historical trends and socioeconomic indices to forecast overweight and obesity rates at national and state levels. Age-cohort analyses were also conducted to explore shifts in age patterns and onset over time.
Uncertainty was addressed through probabilistic modeling, providing robust 95% uncertainty intervals for all estimates. These analyses were performed using R and Python.
Study results
In 2021, the prevalence of overweight and obesity in the USA was strikingly high across all age groups. Among children aged 5-14 years, approximately 15.1 million (95% UI 13.5-16.8) were affected, with an age-standardized prevalence of 36.2% in males and 37.2% in females.
For adolescents aged 15-24 years, 21.4 million (20.2-22.6) were overweight or obese, with a higher prevalence observed in females (50.8%) compared to males (46.7%). Notably, obesity affected 28.8% of adolescent females and 22.7% of males.
Among adults aged 25 years and older, 172 million (169-174) were overweight or obese, with 75.9% of males and 72.6% of females affected. Obesity was more prevalent in adult females (45.6%) than males (41.5%).
State-level analyses revealed significant geographic disparities. Mississippi exhibited the highest prevalence of overweight and obesity among female adolescents (63.0%), while Texas led among males (52.4%).
Obesity prevalence among adolescents exceeded 20% in all states, surpassing 30% in several, with Mississippi again at the forefront. Among adults, the prevalence of obesity varied significantly, ranging from 30.4% in Washington, DC, to 50.5% in West Virginia for males and from 36.0% in Hawaii to 55.9% in Mississippi for females.
Age-specific trends highlighted a sharp rise in obesity prevalence during adolescence, particularly among females, with rates reaching 33.3% by ages 20-24 years.
Among adults, obesity prevalence peaked at 48.7% for females aged 50-54 years and 46.8% for males aged 45-49 years, followed by a decline in older age groups. However, peak ages and prevalence varied by state, reflecting regional differences.
From 1990 to 2021, obesity prevalence increased dramatically, particularly among adolescents. For male adolescents, obesity rose by 158.4%, and for females, it surged by 185.9%. Among adults, obesity increased by 123.6% in males and 99.9% in females. The steepest state-level increases were observed in Utah, New Mexico, and Alabama for males and in Nebraska and Oklahoma for females.
Projections to 2050 suggest a continued rise, with an additional 6.7 million children and adolescents and 41.4 million adults expected to be overweight or obese. Obesity prevalence among adults is forecasted to surpass 55% nationwide, exceeding 60% in several states.
Conclusions
To summarize, this analysis highlights the alarming rise in overweight and obesity in the USA from 1990 to 2021, with projections showing worsening trends through 2050. Nearly three-quarters of adults were overweight or obese in 2021, with obesity rates doubling over three decades.
Forecasts indicate that by 2050, over 80% of adults will be affected, with males showing a faster rate of increase. Adolescent females, particularly in southern states, face a significant burden, with obesity prevalence projected to exceed 50% in some areas by 2050.
