Percentage of US Adults with Metabolically Healthy Obesity Increased in Past 2 Decades

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Results from a new survey suggest that the prevalence of metabolically healthy obesity (MHO) among US adults with obesity has increased significantly in the past 2 decades, with variations across sociodemographic subgroups.

Findings were published March 9, 2023, in JAMA Network Open.

“In the context of the obesity epidemic, better understanding of trends in MHO may facilitate the stratification and treatment of patients with obesity and inform policy efforts. However, whether the proportion of MHO, defined by conventional risk factors and other surrogate markers, has changed over the past 2 decades is largely unknown for US adults,” wrote first author Jiang-Shui Wang, MBBS, of Tongji Medical College in Wuhan, China, and colleagues.

Wang and colleagues analyzed data from 10 National Health and Nutrition Examination Survey (NHANES) cycles from 1999-2000 to 2017-2018. Adults aged ≥20 years who were not pregnant and had blood samples collected were included in the cross-sectional study. Demographic data were collected through questionnaires. Weight, height, waist circumference, and blood pressure (BP) were measured at mobile examination centers. Participants were also asked to provide blood samples at the mobile examination centers to measure lipids, plasma glucose, serum insulin, and C-reactive protein levels. Researchers randomly selected a subset of participants to visit the examination centers in the morning after an overnight fast to measure their triglycerides, fasting plasma glucose (FPG), and insulin levels.

Obesity was defined as a body mass index of ≥30 kg/m². Adults with obesity were classified as having MHO if they had none of the 4 following metabolic syndrome components: elevated BP, elevated FPG, low HDL cholesterol, and elevated triglycerides. The study duration was grouped into 4-year periods: 1999-2002, 2003-2006, 2007-2010, 2011-2014, and 2015-2018.

Findings

There were 20 430 adults included in the study. The mean age of the cohort was 47.1 years, 50.8% were women, and 68.8% self-reported their race and ethnicity as non-Hispanic White. Among the cohort, the age-standardized prevalence of MHO increased from 3.2% in 1999-2002 to 6.6% in 2015-2018 (P<.001).

Of the cohort, there were 7386 adults (mean age, 48 years; 53.5% women) with obesity. Among this group of participants, the age-standardized proportion of MHO increased from 10.6% in 1999-2002 to 15% in 2015-2018 (P=.02), according to the study. “However, this increase was largely due to an increase between 1999-2002 and 2003-2006, and disparities existed among sociodemographic subgroups,” wrote Wang and colleagues.

From 1999-2002 to 2015-2018, the percentage of adults with elevated triglycerides (44.9% to 29%; P<.001) and low HDL cholesterol (51.1% to 39.6%; P=.006) decreased, whereas the proportion of adults with elevated FPG increased (49.7% to 58%; P<.001). There was no change in the percentage of adults with elevated BP.

Investigators observed substantial increases in the proportion of MHO among men, non-Hispanic White persons, adults aged ≥60 years, and those with a higher income, private insurance, and class I obesity.

“These results highlight the need for effective strategies to optimize metabolic status and prevent obesity-related complications among people with obesity, especially among vulnerable subpopulations,” wrote Wang et al. “Priority should be placed on reinforcing glucose management and reducing insulin resistance among individuals with obesity.”

Reference: Wang JS, Xia PF, Ma MN, et al. Trends in the prevalence of metabolically healthy obesity among US adults, 1999-2018. JAMA Netw Open. 2023;6:e232145.