Prevalence and Trends of Adult Obesity in the US, 1999–2012

Aim. To provide national estimates of obesity among US adults aged 20 years and older in 2011-2012 and track its trends from 1999 to 2012. Methods. Measured weight/height from National Health and Nutrition Examination Survey 1999–2012 waves was used to calculate body mass index (BMI) and prevalence measures. Piecewise logistic regressions were conducted to test the differential trends before and after 2010. Results. In 2011-2012, the age-adjusted prevalence of overweight and obesity combined ( ) was 71.1% (95% CI: 68.0%–74.2%) among men and 65.5% (61.8%–69.3%) among women, and the prevalence of obesity ( ) was 33.3% (30.5%–36.2%) among men and 35.8% (32.3%–39.4%) among women. From 1990–2000 to 2009-2010, the prevalence of overweight and obesity combined, obesity, grades 2 and 3 obesity combined ( ), and grade 3 obesity ( ) increased by 7.2%, 17.8%, 17.6%, and 33.0%, respectively. Compared to 2009-2010, most gender- and race/ethnicity-specific prevalence measures remained unchanged or slightly decreased in 2011-2012. No significant difference in trends among prevalence measures was found before and after 2010. Conclusions. Concurrent evidence on the leveling off of obesity in the US is thin. Given its high prevalence and profound socioeconomic consequences, close monitoring of the trend is warranted. 1. Introduction Obesity is a leading risk factor for many adverse health outcomes including type 2 diabetes, hypertension, dyslipidemia, coronary heart disease, and certain types of cancer [1]. The prevalence of adult obesity in the US had doubled from 1976–1980 to 1999-2000 [2]. In 2009 US ranked the highest in adult obesity prevalence among all countries in the Organization for Economic Cooperation and Development [3]. The estimated annual medical cost of obesity in the US totaled 147 billion US dollars in 2008 [4]. More recent data indicated a slowing down of the trend in adult obesity and even some leveling off in childhood obesity. Small but significant declines in the prevalence of obesity among low-income preschoolers aged 2–5 years were reported in 19 of 43 US states examined in the Pediatric Nutrition Surveillance System from 2008 to 2011 [5]. No significant change in the prevalence of adult obesity was found between 2003–2008 and 2009-2010 in the National Health and Nutrition Examination Survey (NHANES) [6]. The prevalence of morbid (i.e., grades 2 and 3) obesity was still increasing from 2005 to 2010, but its growth rate had slowed down as indicated in the Behavioral Risk Factor Surveillance System (BRFSS) [7]. Given the large disease burden of