A study published in the Journal of the American Medical Association on Tuesday reports that, although the obesity rate in the United States has stabilized, American waistlines still continue to get larger every year.

According to data gathered by the Centers for Disease Control (CDC) and the National Health and Nutrition Examination Survey (NHANES), American waistlines grew more than an inch among different demographics over the last decade, making the national average among adults 39 inches.

Like Us on Facebook

Meanwhile, numbers for the Body Mass Index (BMI), which is determined by weight-to-height ratio and is used to help measure obesity, have stabilized even though belly circumference continues to expand.

Researches said that it is unclear why waistlines are getting bigger while BMI has flat-lined.  Possible contributors could be sleep problems, certain types of medication, lack of exercise and proper diets, and an aging population.

"As we age, heavy muscle is lost and we gain more fat," said David Heber, director of UCLA Risk Factor for Obesity Clinic.

The obesity and abdominal circumference study was based on data collected by NHANES to assess the weight of 32,816 individuals from across the United States between the years 1999 and 2012. The people surveyed were 20-years-old and above, with the national average for ages of adults during that time being 45-years-old.

Experts found that adult waistlines grew from an average of 37.6 inches in 2000, to 38.8 inches in 2012, to the present number which venture dangerously close to what is considered abdominal obesity - 40.2 inches for men, and 34.6 inches for women.

In fact, at 37.8 inches, the national average waistline for American women is already considered obese.

According to health care experts, carrying around excess stomach fat is extremely dangerous.  People who suffer from excess fat in the belly area put themselves at greater risk for heart disease, sleep apnea, diabetes, and high cholesterol.

Tagsobesity, americas waistlines, obesity in america, U.S. obesity, expanding waistlines, excess weight, overweight