Trends in Obesity Among Adults in the United States

Study Questions:

Has the prevalence of obesity among adults increased in the past decade?


Data from the National Health and Nutrition Examination Survey (NHANES), a cross-sectional, nationally representative health examination survey of the US civilian noninstitutionalized population, were used for the present analysis. Trends in rates of obesity were compared from 2005 to 2014. The primary outcomes of interest were prevalence of obesity (body mass index [BMI] ≥30 kg/m2) and class 3 obesity (BMI ≥40 kg/m2).


Data from 2,638 men (mean age 46.8 years) and 2,817 women (mean age 48.4 years) from the most recent 2 years of NHANES 2013-2014, as well as data from 21,013 adults in prior NHANES surveys (from 2005-2012) were used to examine trends over time. The most recent (2013-2014) age-adjusted prevalence of obesity was 37.7% (95% confidence interval [CI], 35.8%-39.7%). The prevalence of obesity was higher among women (40.4% [95% CI, 37.6%-43.3%]) compared to men (35.0% [95% CI, 32.8%-37.3%]). Class 3 obesity prevalence was 7% (95% CI, 6.2%-9.3%) in 2013-2014. Among men, class 3 obesity was 5.5% (95% CI, 4.0%-7.2%), and among women, the prevalence was 9.9% (95% CI, 7.5%-12.3%). Since 2005, significant increasing linear trends were observed among women for overall obesity (p = 0.004) and for class 3 obesity (p = 0.01), but not among men (p = 0.30 for overall obesity; p = 0.14 for class 3 obesity) after adjusting for age, race/Hispanic origin, smoking status, and education.


The investigators concluded that in this nationally representative survey of adults in the United States, the age-adjusted prevalence of obesity in 2013-2014 was 35.0% among men and 40.4% among women. The corresponding values for class 3 obesity were 5.5% for men and 9.9% for women. For women, the prevalence of overall obesity and of class 3 obesity showed significant linear trends for increase between 2005 and 2014; there were no significant trends for men. Other studies are needed to determine the reasons for these trends.


These data suggest that almost 40% of US adults are obese. Given the increases over the past decade of obesity, including severe obesity among women, interventions to prevent obesity and promote weight loss among those who are obese will likely result in significant public health benefits.

Clinical Topics: Diabetes and Cardiometabolic Disease, Prevention

Keywords: Adult, Body Mass Index, Metabolic Syndrome X, Nutrition Surveys, Obesity, Obesity, Morbid, Prevalence, Primary Prevention, Public Health, Weight Loss, Women

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