If you were confused this week by headlines proclaiming that “nearly half of Americans will have obesity by 2035,” don’t feel bad. It means you are paying attention. Because this proclamation flies in the face of headlines from last year telling us obesity rates are declining in the U.S.

So what gives?

The New Research

The headlines come from a sweeping new analysis in JAMA. The study is noteworthy because it provides solid data to tell us how deeply obesity has taken hold across the United States. And how unevenly its burden is shared.

Drawing on more than 11 million data points from national surveys, rigorously corrected for self-report bias, researchers estimated obesity prevalence from 1990 to 2022 and projected trends through 2035 across states, ages, sexes, and major racial and ethnic groups. Their findings are stark. In 2022, 42.5% of U.S. adults – about 107 million people – were living with obesity. Of course, that’s more than double the prevalence in 1990.

By 2035, the researchers project a rise to nearly 47%, or 126 million adults. They forecast 2035 obesity rates using a multi-model ensemble built on past trends plus demographics. It’s not a straight-line extrapolation. Rather it is a probability-weighted synthesis of multiple trend and demographic models grounded in three decades of data.

Rule #1 of Forecasts

To put this new research in perspective, remember the number one rule of forecasts. They’re invariably wrong. Yogi Berra and a whole string of wise ones figured this out long ago. It is hard enough to pin down present trends. For obesity, they seem to point to a leveling out in the combined prevalence of overweight and obesity. But the 75% of the population living with excess weight seem to be progressing toward more severe states of their condition.

Perhaps better treatment access will slow or reverse that trend. Perhaps it won’t. For now, all we have is speculation. The forecast published this week assumes that “past trends continue” to 2035.

We can tell you with confidence that those trends will change. How they will change is anything but certain.

Click here for the study, here, here, and here for further perspective.

Sunrise Over the Mongolian Plateau, painting by Fujishima Takeji / WikiArt