A CHOICES study finds that about half of the adult U.S. population will have obesity and about a quarter will have severe obesity by 2030. Severe obesity—once a rare condition—is projected to be the most common BMI category in 10 states and in some demographic subgroups.
Ward ZJ, Bleich SN, Cradock AL, Barrett JL, Giles CM, Flax CN, Long MW, Gortmaker SL. Projected U.S. State-Level Prevalence of Adult Obesity and Severe Obesity. N Engl J Med. 2019;381:2440-50. doi: 10.1056/NEJMsa1909301
According to this CHOICES study, about half of the adult U.S. population will have obesity and about a quarter will have severe obesity by 2030. The study also predicts that in 29 states, more than half of the population will have obesity, and all states will have a prevalence of obesity higher than 35%. The study’s researchers estimate that, currently, 40% of American adults have obesity and 18% have severe obesity.
The researchers said the predictions are troubling because the health and economic effects of obesity and severe obesity take a toll on several aspects of society.
“Obesity, and especially severe obesity, are associated with increased rates of chronic disease and medical spending, and have negative consequences for life expectancy,” said Steven Gortmaker, Professor of the Practice of Health Sociology at the Harvard T.H. Chan School of Public Health and senior author of the study.
For the study, the researchers used self-reported body mass index (BMI) data from more than 6.2 million adults who participated in the Behavioral Risk Factor Surveillance System Survey (BRFSS) between 1993 and 2016. Body mass index (BMI) is calculated by dividing a person’s weight in kilograms by the square of their height in meters. Obesity is defined as a BMI of 30 or higher, and severe obesity is a BMI of 35 or higher. Self-reported BMIs are frequently biased, so the researchers used novel statistical methods to correct for this bias.
The large amount of data collected in the BRFSS allowed the researchers to drill down for obesity rates for specific states, income levels, and sub-populations. The results showed that by 2030, several states will have obesity prevalence close to 60%, while the lowest states will be approaching 40%. The researchers predicted that nationally, severe obesity will likely be the most common BMI category for women, non-Hispanic black adults, and those with annual incomes below $50,000 per year.
“The high projected prevalence of severe obesity among low-income adults has substantial implications for future Medicaid costs,” said lead author Zachary Ward, Programmer/Analyst at the Harvard T.H. Chan School of Public Health’s Center for Health Decision Science. “In addition, the effect of weight stigma could have far-reaching implications for socioeconomic disparities as severe obesity becomes the most common BMI category among low-income adults in nearly every state.”
Ward and his co-authors said that the study could help inform state policy makers. For example, previous research suggests that sugary drink taxes have been an effective and cost-effective strategy for curtailing the rise in obesity rates. “Prevention is going to be key to better managing this epidemic,” said Ward.
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Lead author Zach Ward discusses the paper with the Center for Health Decision Science.