JAMA Authors Report Two-Thirds of US Adults Are Overweight or Obese

More than two-thirds of Americans age 25 and older are overweight or obese, according to authors who published an analysis today in JAMA Internal Medicine.

Graham A. Colditz, MD, DrPH, and Lin Yang, PhD,, both of the Washington University School of Medicine in Saint Louis, Missouri, reviewed data from the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2012 to arrive at their estimate. Their sample, from 15,208 men and women, was representative of the US population of more than 188 million.

Their study estimates that 39.6% of men, or 36.3 million, and 29.74% of women, or nearly 28.9 million, were overweight. Also, 35.04% of men, or 31.8 million, and 36.84% of women, or 35.8 million, were obese. The authors classified persons as overweight using the standard definition of body mass index (BMI) between 25 kg/m² and 29.9 kg/m² and obesity as anyone with a BMI above 30 kg/m².

Being overweight or obese invites a host of health risks; it is the single greatest risk factor for developing type 2 diabetes mellitus. According to the American Diabetes Association, diabetes now affects 29.1 million Americans, including 25% of all seniors.

Within the category of persons who were obese, the authors further classified patients as those in Class 1 (with BMI of 30.0 to 34.9 kg/m²), those in Class 2 (with BMI of 35 to 39.9 kg/m²), and those in Class 3 (with BMI of 40 kg/m² or greater. Across all ethnic groups and subgroups, more patients were overweight than obese; among the obese, more were in Class 1 than in Class 2 or 3, and the smallest percentages were seen in Class across all subgroups.

However, the authors noted that compared with 1988 to 1994, Americans are gaining weight across the board. While the data show minority populations are at higher risk, white Americans are not immune to the trend. Among men, Mexican-Americans had the smallest share still at normal weight at 18.75%, while among women, African-American women had the smallest share still at normal weight at 15.79%; this group had the highest percentage in the category of Class 3 obesity, at 17.30%.

The likelihood of being overweight or obese rose with age. Among men, the share at normal weight was 25.05% among those 25 to 54 years of age, and it fell to 22.78% for those age 55 and older. Among women, 33.45% age 25 to 54 were normal weight, and that percentage fell to 28.01 among those age 55 or older.

“The rising trends in overweight and obesity warrant timely attention from health policy and healthcare system decision makers,” the authors write. Most of the emphasis today is on screening and prevention of diseases rather than on weight gain itself, they said, which overlooks those at normal weight who may be at risk of weight gain.

“Population based strategies helping to reduce modifiable risk factors such as physical environmental interventions, enhancing primary care efforts to prevent and treat obesity, and altering social norms of behavior are required,” they wrote. The authors cited the 2012 Institute of Medicine report that called for prevention strategies that included physical activity, healthier diets, and changing social norms.

Such strategies can prove tough to implement, however. This year, the 2015 Dietary Guidelines Advisory Committee made recommendations for a national nutrition strategy with less red and processed meat and more plant-based diets. The group’s report faced stiff resistance from the beef industry, and departments that must sign off on the final guidelines have not yet issued them.

Efforts to revamp the National School Lunch Program have also been met with resistance from school districts who say that students refuse to eat some of the offerings. Critics of the school lunch changes say that it is hard for school cafeterias to enforce healthy eating when they face competition from fast food and unhealthy options sold at gas stations.

Still, there are some efforts afoot to take aim at obesity. Berkeley, California, last fall passed the nation’s first soda tax, and San Francisco is weighing warning labels on outdoor advertising for sugary drinks.

Reference

Colditz GA, Yang L. Prevalence of overweight and obesity in the United States, 2007-2012 [published online June 22, 2015]. JAMA Intern Med.

For a copy of the study, click here.