Possible reasons include sleep deprivation and medication, says a new study.

Streeeettcchhh... that's the sound of the nation's stomach expanding. Americans are now more than an inch fatter around the waist on average than they were in the late '90s, though among certain demographics the increase has been nearly twice that.

The waist circumference of American citizens in 1999 and 2000 averaged 37.6 inches, according to a new study from the Centers for Disease Control and Prevention and others. By 2011 and 2012, it had swelled to 38.8 inches. That almost qualifies for the medical definition of abdominal obesity for men (a waist circumference of greater than 40.2 inches) and exceeds it for women (34.6 inches).

In their analysis of nearly 33,000 U.S. adults, the researchers noted significant expansions in waistlines among a few groups. Mexican Americans logged the biggest increase with 1.8 inches, while blacks also went up a belt size—1.6 inches and women of 1.5 inches. White people got an average of 1.2 inches larger, and white men in particular swelled up by 0.8 inches.


The proportion of the population that falls into the category of abdominally obese (or as the Urban Dictionary gently calls it, "abdominally enhanced") has likewise shot up. About 54 percent of Americans can now claim that label, an increase of roughly 8 percent since the start of the millennium. Almost 65 percent of females today have abdominal obesity, as do about 44 percent of males.

This study is surprising not only in its worrisome health findings, but in its dismissal of the idea that there was a "pause" in waistline growth several years back. The researchers say:

The authors write that previous analyses of data from [the National Health and Nutrition Examination Survey] show that the prevalence of obesity calculated from body mass index (BMI) did not change significantly from 2003-2004 to 2011-2012. "In contrast, our analyses using data from the same surveys indicate that the prevalence of abdominal obesity is still increasing. The reasons for increases in waist circumference in excess of what would be expected from changes in BMI remain speculative, but several factors, including sleep deprivation, endocrine disruptors, and certain medications, have been proposed as potential explanations."

As for what to do about all of this, the researchers suggest that health practitioners regularly measure people's waists "as a key step in initiating the prevention, control, and management of obesity among patients."

(Top image via kurhan/Shutterstock.com.)

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