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Americans’ waistlines grow as obesity rates level off, study finds


The average American woman’s waist size has increased at a much faster rate than the average American man’s, according to a study published last Tuesday in JAMA, which examined federal health surveys of nearly 33,000 Americans from 1999 to 2012. The study found the average woman’s waist size increased by 1.5 inches, the average man’s by 0.8 inches.

Nearly 44 percent of men and 65 percent of women have what’s called “abdominal obesity,” which typically indicates an excess of metabolically active fat that interferes with proper functioning of the kidney, liver, and other organs. It compares to 37 percent of men and 55 percent of women who had abdominal obesity in 1999.


Such individuals have a waist size of 40 inches or greater for a man or 35 inches or greater for a woman; this puts them at higher risk of diabetes, heart disease, and certain cancers compared to those with smaller waists and larger hips.

Oddly, previous analyses using the same data have shown that the prevalence of obesity — based on a calculation comparing body weight with height — hasn’t changed significantly over the past decade. Hence, there’s a growing number of people who aren’t technically obese but who have abdominal obesity.

It’s tough to explain why abdominal girth keeps increasing while obesity rates remain fairly steady, said study leader Dr. Earl Ford, a medical officer at the federal Centers for Disease Control and Prevention. D.K.

Deborah Kotz can be reached at dkotz@globe.com. Follow her on Twitter @debkotz2.