Prevalence of obesity in U.S. increases among women, but not men

Between 1980 and 2000, the prevalence of obesity increased significantly among adult men and women in the United States; further significant increases were observed through 2003-2004 for men but not women. Subsequent comparisons of data from 2003-2004 with data through 2011-2012 showed no significant increases for men or women. To get a more comprehensive understanding of the trends in obesity, Katherine M. Flegal, Ph.D., of the National Center for Health Statistics, Centers for Disease Control and Prevention, Hyattsville, Md., and colleagues examined obesity prevalence for 2013-2014 and trends over the decade from 2005 through 2014, adjusting for sex, age, race/Hispanic origin, smoking status, and education. The researchers analyzed data obtained from the National Health and Nutrition Examination Survey (NHANES), a cross-sectional, nationally representative health examination survey of the U.S. civilian population that includes measured weight and height.

The analysis included data from 2,638 adult men (average age, 47 years) and 2,817 women (average age, 48 years) from the most recent 2 years (2013-2014) of NHANES and data from 21,013 participants in previous NHANES surveys from 2005 through 2012. For the years 2013-2014, the overall age-adjusted prevalence of obesity (body mass index [BMI] 30 or greater) was 38 percent; among men, it was 35 percent; and among women, it was 40 percent. The corresponding prevalence of class 3 (BMI 40 or greater) obesity overall was 7.7 percent; among men, it was 5.5 percent; and among women, it was 9.9 percent. Analyses of changes over the decade from 2005 through 2014, adjusted for age, race/Hispanic origin, smoking status, and education, showed significant increasing linear trends among women for overall obesity and for class 3 obesity but not among men.

Analyses of the data from 2013-2014 found that for men, obesity prevalence varied by smoking status, with the prevalence of obesity significantly lower among current smokers than among never smokers. For women, there were no significant differences by smoking status, but those with education beyond high school were significantly less likely to be obese.

The authors write that although there has been considerable speculation about the causes of the increases in obesity prevalence, data are lacking to show the causes of these trends, and there are few data to indicate reasons that these trends might accelerate, stop, or slow. "Other studies are needed to determine the reasons for these trends."

Editorial: The Unrelenting Challenge of Obesity

"What is the next step in addressing the epidemic of obesity?" write Jody W. Zylke, M.D., Deputy Editor, JAMA, and Howard Bauchner, M.D., Editor in Chief, JAMA, in an editorial commenting on the two studies in this issue of JAMA examining trends of obesity in the U.S.

"Much research and attention have been directed toward treatment of obesity, but the development of new drugs and procedures will not solve the problem. Perhaps genetics will unlock some of the mysteries of obesity, but this will take time, and more immediate solutions are needed. The emphasis has to be on prevention, despite evidence that school- and community-based prevention programs and education campaigns by local governments and professional societies have not been highly successful."

"The obesity epidemic in the United States is now 3 decades old, and huge investments have been made in research, clinical care, and development of various programs to counteract obesity. However, few data suggest the epidemic is diminishing. Perhaps it is time for an entirely different approach, one that emphasizes collaboration with the food and restaurant industries that are in part responsible for putting food on dinner tables."