Americans Are Still Getting Larger

A sobering new study by researchers from the Centers for Disease Control and Prevention (CDC) shows that American adults are still getting heavier.

Data from the National Health and Nutrition Examination Survey (NHANES) showed that the overall average waist circumference of more than 32,800 participants increased “progressively and significantly” from 37.6 inches in 1999-2000 to 38.8 inches in 2011-2012–a 54.2% increase.

The data, which was published in JAMA, also underlines why it’s problematic to base weight status and health on body mass index (BMI). The researchers note that prior analyses using the exact same surveys but focusing on BMI have concluded that obesity prevalence has not changed significantly and perhaps even leveled off. The researchers write that positive developments in eating and exercise “have given hope that the decades-long increase in the prevalence of obesity in the United States may have crested.” But their data shows abdominal obesity is actually increasing.

There’s debate over whether we should stop using BMI as a measure for obesity since the numbers can be misleading. For instance, some people may have a lot of good lean muscle that puts them in a heavier category. Waist circumference is more indicative of where body fat is resting, and it’s well established that the fat hugging the belly is considered the most dangerous for future health problems. A continuous increase in waist circumference is therefore a bad sign.

Study author Dr. Earl S. Ford of the CDC says they don’t have a great explanation for the findings, but the reason waist circumference may still be rising even if BMI isn’t could have to do with factors like sleep deprivation, hormones or certain medications.

Obesity in the U.S. is an epidemic, and about one third of U.S. adults qualify as obese. As a nation, we haven’t exactly been ignoring the trend: The government launched the Let’s Move! campaign to increase physical activity in young people, and overhauls of school lunches have provided healthier options. So what’s not working?

Some research has shown that it’s not just what people are eating that contributes to obesity, but the fact that we lead such sedentary lives. Other research shows that both parents and kids have stopped seeing obesity as a problem. In August, research published in the journal Pediatrics showed mothers often do not view their kids as overweight, possibly because their child fits the norm of his or her peers. “We rarely compare our weight status against an absolute scale or a number recommended by doctors,” said study author Dr. Jian Zhang of Georgia Southern University in an interview with TIME. “Instead we compare to what our friends, neighbors, and coworkers look like.” Another recent report published in JAMA showed that misperceptions about whether young people are overweight are common among both youth and their parents.

“[The results] are not a great surprise. It’s amazing how much we are not doing right…A lot of entities in our culture don’t want the confusion to end,” says Dr. David Katz, founding director of the Yale University Prevention Research Center. “I do respect the argument about nanny states, but there has to be some basic propriety attached to this. Peddling junk food to children is just wrong.”

Katz argues that even the best advice can’t succeed if there’s mixed messaging, like when Olympic athletes promote McDonald’s or Coca Cola. If we can parse through the confusion, the tried and true ways to maintain weight are the same. If we stick to them, maybe our waistlines can stay the same, too–or even one day start to get smaller.