Prevalence of metabolically healthy obesity increasing in US, but remains low overall
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The percentage of adults with metabolically healthy obesity increased from 1999 to 2018 but remains much smaller than the proportion of those with metabolically unhealthy obesity, according to study data.
In findings from the National Health and Nutrition Examination Survey published in JAMA Network Open, the age-standardized prevalence of metabolically healthy obesity increased from 3.2% in 1999-2002 to 6.6% in 2015-2018 (P < .001). However, among adults with obesity, only 15% had metabolically healthy obesity in 2015-2018.
“Although the age-standardized proportion of adults with metabolically healthy obesity increased in the past two decades, the absolute number of adults with metabolically unhealthy obesity has increased dramatically, which may still be a major health concern,” An Pan, PhD, professor of epidemiology in the department of epidemiology and biostatistics, School of Public Health at Tongji Medical College, Huazhong University of Science and Technology in China, told Healio. “Effective strategies are needed to optimize metabolic status among individuals with obesity to prevent cardiovascular and metabolic comorbidities.”
Pan and colleagues analyzed data from 10 NHANES cycles from 1999-2000 to 2017-2018. Adults aged 20 years and older who were not pregnant and had blood samples collected were included. Demographic data were collected through questionnaires. Weight, height, waist circumference and blood pressure were measured at mobile examination centers. Participants provided blood samples to measure lipids, plasma glucose, serum insulin and C-reactive protein levels. A subset of participants were randomly selected to attend visits in the morning after an overnight fast. Those participants had blood samples taken to measure triglycerides, fasting plasma glucose and insulin. Obesity was defined as a BMI of 30 kg/m2 or more. Adults had metabolically unhealthy obesity if they had any of the four following metabolic syndrome components: elevated BP, elevated FPG, low HDL cholesterol and elevated triglycerides. Participants with none of those components were considered to have metabolically healthy obesity. The study duration was grouped into 4-year periods: 1999-2002, 2003-2006, 2007-2010, 2011-2014 and 2015-2018.
There were 20,430 adults included in the study (mean age, 47.1 years; 50.8% women). Of the cohort, 7,386 adults had obesity. The age-standardized prevalence of obesity increased from 28.6% in 1999-2002 to 40.9% in 2015-2018 (P < .001). The prevalence of metabolically unhealthy obesity increased from 25.4% in 1999-2002 to 34.3% in 2015-2018 (P < .001) and the prevalence of metabolically healthy obesity increased from 3.2% in 1999-2002 to 6.6% in 2015-2018 (P < .001).
Among adults with obesity, the percentage of those with metabolically healthy obesity increased from 10.6% in 1999-2002 to 15% in 2015-2018 (P = .02). Most of the increase was attributable to an increase between 1999 and 2006, and the rate of metabolically healthy obesity did not significantly change from the 2003-2006 to 2015-2018 cycles.
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.
“Multilevel strategies are needed to optimize metabolic status among individuals with obesity to address the double burden of obesity and metabolic disorders,” Pan said. “To reduce inequities in cardiometabolic health among people with obesity, more accessible strategies that reach racial and ethnic minority individuals and those residing in low-income communities should be implemented.”
Pan added that more studies are needed to better define metabolically healthy obesity and to examine obesity phenotypes in greater detail.
“Future studies need to further clarify the potential value of the concept of obesity phenotypes in refining current obesity diagnosis, risk stratification, and targeted treatment,” Pan said.
For more information:
An Pan, PhD, can be reached at panan@hust.edu.cn.
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