Anyone not living under a rock is aware that the prevalence of obesity in this country (and indeed around the world) has been increasing for decades. In this country alone, the spread of obesity (BMI>30) and severe obesity (BMI>40) has been appalling. For example, in 2011 between 30 and 35 percent of adults in 12 states had a BMI of 30 or more. By 2016, 25 states were in that category, and 5 of those had a prevalence of 35 percent or more.
So how are we doing now? A recent report provides a mixed message. Dr. Craig M. Hales and colleagues from the CDC analyzed trends in obesity prevalence of both adults (18 +) and youth (7-17 years) between NHANES surveys* in 2007-08 and 2015-16. For the younger group, obesity was defined as BMI at or above the 95th percentile of sex-specific BMI-for-age, and severe obesity meant such a BMI greater than 120 percent of the norm.
The data they analyzed reflected the status of nearly 17,000 youth and over 27,000 adults. For adults, the results were somewhat discouraging — from a prevalence of obesity of about 34 percent in the first survey, it increased to about 40 percent by the second one — a highly significant increase. More discouraging was the finding that the prevalence of severe obesity also increased — from 5.7 percent in 2007-08 to 7.7 percent in 2015-16, again a significant change.
On the other hand, results from the younger group provide some hope, with no significant increase in the prevalence of obesity or severe obesity overall.
While the results of the surveys in adults are discouraging, they reflect how difficult it is to deal with obesity once it has become established. The lack of progression of obesity prevalence in the youths provides some hope that perhaps public health messages warning parents of the health problems linked to obesity have hit their targets. We shall have to await further surveys to determine if these results hold.
*NHANES (National Health and Nutrition Examination Survey); they involve direct measurements of height and weight of participants.
