Waistlines Are Continuously Expanding in the United States

New findings published in the Journal of the American Medical Association show that many Americans have an an ever-expanding waistline.

The study, conducted by researchers at the U.S. Centers for Disease Control and Prevention, Atlanta, shows that the average waistline for U.S. residents has increased by 1 inch (2.5 cm) between 1999 and 2012, according to the BBC.

For their findings, researchers used data from the National Health and Nutrition Examination Survey (NHANES); this involved 32,816 men and non-pregnant women. The researchers obtained information about participants' age and waist circumference.

In the study, abdominal obesity was defined as waist circumference greater than 34.6 inches (88 cm) in women and 40.2 inches (102 cm) in men.

Findings showed that the waist circumference increased in both genders as well as across both genders in different ethnicities. Furthermore, waist size expanded from 37.6 inches in 1999 to 2000 to 38.8 inches in 2011 to 2012.

Throughout this period, men's waist circumference increased by about 0.8 inches, while women's increased by about 1.5 inches. Non-Hispanic white participants' waist circumference increased by about 1.2 inches while non-Hispanic black participant's waist circumference increased by about 1.6 inches. Mexican American's saw the greatest increase by about 1.8 inches.

"Our results support the routine measurement of waist circumference in clinical care consistent with current recommendations as a key step in initiating the prevention, control, and management of obesity among patients," researchers concluded, in a news release. 

The study authors are still uncertain why waistlines seem to expand faster than BMI. However, they suggest that numerous factors, ranging from sleep and genetics to medication side effects can contribute to extra fat in the midsection.