U.S. obesity rates may have stabilized in recent years, but our waistlines are still expanding, according to new research published late last week in the Journal of the American Medical Association (JAMA).
That’s not good news. A large waistline — a sign of excessive abdominal fat — is a risk factor for a variety of serious medical conditions, including type 2 diabetes and heart disease, no matter what weight category (normal, overweight or obese) your body mass index (BMI) puts you in.
It’s also a risk factor for premature death.
For these reasons, experts at the National Heart, Lung and Blood Institute (NHLBI) and elsewhere recommend that women not let their waistline expand beyond 35 inches and men beyond 40 inches.
Method and results
For the new study, researchers at the Centers for Disease Control and Prevention used data collected from the National Health and Nutrition Examination Survey (NHANES) to compared the average age-adjusted waist circumferences of American adults in 1999-2000 with those in 2011-2012.
They found that our waistlines increased, on average, about 3 percent over those 14 years. In 1999 and 2000, the average waist in the U.S. measured 37.6 inches. By 2011 and 2012, it had expanded to 38.8 inches.
They also found that the trend occurred in most demographic groups — among men as well as women and among non-Hispanic whites, non-Hispanic blacks and Mexican-Americans.
The CDC researchers were unable to determine if the trend had also occurred in Asian-Americans, however, because NHANES didn’t start collecting waistline data on that demographic group until 2011.
The report noted that five groups experienced “particularly large” average increases in abdominal fat between 1999 and 2012:
- White women in their 40s: 2.6 inches
- Black men in their 30s: 3.1 inches
- Mexican-American men in their 20s: 3.4 inches
- Mexican-American women aged 70 years or older: 4.4 inches
- Black women in their 30s: 4.6 inches
The researchers cite the increasing number of people who are chronically sleep deprived and the growing use of endocrine-disrupting chemicals and medications as possible contributors to the rapid expansion of Americans’ bellies. Each of these factors is known to interfere with the body’s ability to properly regulate how — and where — energy (calories in consumed food) is stored.
“At a time when the prevalence of obesity may have reached a plateau, the waistlines of U.S. adults continue to expand,” the CDC researchers write. They urge physicians to routinely measure waist circumferences of their patients to help with the prevention, control and management of obesity.
FYI: To correctly measure your waistline, the NHLBI recommends that you stand and place a tape measure around your middle, just above your hipbones. Take the measurement just after you have breathed out.