Obesity rates are down. Is that because of weight-loss drugs?

The CDC’s recent findings come from a long-running survey known as the National Health and Nutrition Examination Survey, or NHANES, which employs health experts to collect information like weight and height measurements from a nationally representative sample of study participants. Obesity and severe obesity are determined based on body mass index, and results are reported every two years.

Although the recent dip in the overall obesity rate is promising on its face, the survey also found a slight uptick in the percentage of people with severe obesity. As reported by The Associated Press, experts say it’s unclear what might be behind this increase. Furthermore, without granular, patient-level data that links people’s BMI categories to their GLP-1 drug usage, researchers can’t properly ascertain whether the medications are impacting rates of obesity and severe obesity.

In addition, the recent dip in the overall obesity rate was not statistically significant. In other words, the numbers are “small enough that there’s mathematical chance they didn’t truly decline,” according the same article from The Associated Press. And further, the CDC reports that the prevalence of obesity has barely changed over a 10-year period. This contrasts with rates of severe obesity, which did increase from 7.7 to 9.7 percent in surveys running from 2013 to 2023.

In addition, the decline in overall obesity rate reported by the CDC isn’t the first such drop. Between 1999 and 2018, the NHANES results found two instances of slight decreases in obesity rates and two dips in severe obesity rates. These falls were followed by steady increases in both categories.

Don’t jump to conclusions

But with the increased use of GLP-1s, haven’t we reached a tipping point? After all, around 12 percent of American adults have used a GLP-1 agonist, according to a KFF Health Tracking Poll, and about 6 percent, or roughly 15.5 million people, currently take one. The poll also found that just 38 percent of those taking GLP-1 drugs did so mainly to lose weight. A much larger percentage, around 62 percent, said they have taken GLP-1 drugs as a treatment for diabetes, heart disease, or another chronic condition.