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Obesity affects more than half of US adults
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More than half of U.S. adults currently have obesity or have had the condition at some point in their lifetime, suggesting that the population burden of obesity is larger than indicated by data on current BMI, according to an analysis of survey data published in the American Journal of Preventive Medicine.
“Prior research has found that the health effects of obesity are cumulative, implying that a member of the normal-weight category who was formerly overweight or obese may be at higher risk of experiencing obesity-related health outcomes than those who have always maintained normal weight,” Andrew Stokes, PhD, assistant professor in the department of global health and an affiliate of the Center for Global Health and Development at the Boston University School of Public Health, and colleagues wrote. “Additionally, some people who have experienced weight loss may have done so as a result of age-related loss of lean muscle mass, known as sarcopenia, or an illness, with disease-associated weight loss particularly prevalent among older ages and in certain high-risk subpopulations, such as smokers and those with a history of illness.”
Stokes and colleagues analyzed data from 52,819 participants in the 1988-1994 and 1999-2014 waves of the National Health and Nutrition Examination Survey. Researchers assessed lifetime maximum weight, obtained from a question that asks respondents to recall their maximum lifetime weight, excluding during pregnancy for women. Maximum weight was combined with height measured at survey time to determine lifetime maximum BMI. Researchers identified participants as never vs. ever obese (BMI 30 kg/m²) and further stratified participants with obesity as currently obese or formerly obese (lifetime maximum BMI 30 kg/m², but current BMI 30 kg/m²). Researchers used logistic regression models to estimate associations between age, race, education and smoking status and the likelihood of currently or ever having obesity, as well as the prevalence of several obesity-related diseases using the never-obese group as a reference.
In 2013-2014, 50.8% of men and 51.6% of women had obesity either currently or formerly, according to NHANES survey data, with 30.3% of men and 23.6% of women at normal weight but with a history of obesity.
“The common transitions from currently obese to formerly obese mean that a high proportion of those who were not obese at survey had previously been obese: 23.8% among men and 20.1% among women,” the researchers wrote, noting that the percentage of people who currently or ever had obesity peaked in the age range of 55 to 69 years.
The researchers also observed racial differences in weight histories, particularly among women. Among white women, 51% never had obesity, whereas only 30.4% of black women had no history of obesity.
“Not only were black women more likely to have been obese than white women, but their obesity was more persistent: 19.3% of black women who have ever been obese have exited the status compared to 25.1% of white women,” the researchers wrote.
Researchers found that the proportion of adults with obesity rose steadily from the 1988-1994 wave to the 2013-2014 wave, from 22.5% to 37.4%, and the proportion who had ever had obesity increased from 33.7% to 51.2%. The proportion of ever-obese rose from 11.2% in 1988 to 13.8% in 2014. Among those without obesity in 1988, 14.4% reported a history of obesity, whereas in 2014, 22% of normal-weight adults reported having obesity in the past.
“An investigation of the association between lifetime weight status and prevalent disease further revealed that those with a history of obesity had a higher prevalence of each of the eight diseases examined compared to those who had never been obese,” the researchers wrote. “The finding that, among non-obese individuals, those with a history of obesity have a higher prevalence of disease highlights the importance of separately considering this subpopulation in population monitoring of the obesity epidemic.” – by Regina Schaffer
Disclosure: Stokes reports he receives research funding from Johnson & Johnson.
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