For decades, rates of obesity in the US have climbed 鈥� but that trend may be changing. The number of adults with obesity dipped ever so slightly in 2023, suggesting the country has reached a turning point in this public health crisis. The rise of weight-loss drugs, such as Ozempic and Wegovy, has prompted some to suggest these may be driving the shift. But it isn鈥檛 that simple.
Obesity rates began to rise in the US during the 1970s. Between 1976 and 1980, of adults in the country were considered obese. By 2000, that number had exceeded 30 per cent. Now, more than of US adults have obesity, a condition that markedly increases the risk of heart disease, type 2 diabetes, stroke and certain cancers. Many other countries have seen a similar trend, from the UK and Australia to Mexico and India.
Poor nutrition and sedentary lifestyles are often blamed for the epidemic. Yet obesity rates have refused to budge in the face of countless public health campaigns aimed at improving diet, curbing calorie intake and increasing physical activity. 鈥淥bviously there have been many efforts to curb this epidemic 鈥� calorie labelling and new nutrition guidelines, as an example 鈥� and we鈥檝e yet to see any real measurable impact,鈥� says at Harvard University.
Advertisement
That is why it came as a shock when he and his colleagues found obesity rates had declined in 2023. Over a decade, they collected nearly 48 million measurements of body mass index (BMI) from more than 16.7 million adults in the US. They found that the proportion of those with obesity 鈥� defined as a BMI of 30 or greater 鈥� rose each year between 2013 and 2021, from about 40 per cent to almost 45 per cent. It then plateaued in 2022 before dipping in 2023, though only by a small amount: less than 1 per cent.
Still, the finding is noteworthy. 鈥淲e鈥檝e been seeing an increase [in BMI] every year for as long as we can remember,鈥� says Brownstein. 鈥淪o even the fact that we鈥檙e seeing anything at a population level is important and striking.鈥�
Yet what is driving this isn鈥檛 entirely clear. Brownstein and his colleagues believe it may be due to medications like Ozempic and Wegovy, which contain a drug called semaglutide that can help people lose up to 15 per cent of their body weight in a year. Semaglutide was approved in the US for treating type 2 diabetes in 2017 and for treating obesity in 2021. Nearly there 鈥� about 1.7 per cent of the population 鈥� were prescribed semaglutide in 2023.
The researchers examined insurance claims for about 10.6 million of the people in their study. This showed that 6 per cent of those participants in the southern US had received semaglutide compared with 5.1 per cent in the north-east, 4.4 per cent in the Midwest and 3.4 per cent in the western part of the country. The south was the only region to see obesity rates decline, so Brownstein says this suggests that semaglutide was the main driver.
However, the covid-19 pandemic probably played a substantial role. 鈥淚 really think that this [trend] is most likely, unfortunately, just showing the tragic loss of lives from covid-19 that really struck people who had obesity and other conditions,鈥� says at Tufts University in Massachusetts.
Obesity significantly raises the risk of dying from covid-19. Other health conditions associated with obesity, such as heart disease, diabetes and high blood pressure, raise the risk even further. Not only does the southern US have some of the in the country, but it also had the . The modest difference in semaglutide prescriptions between the south and other regions isn鈥檛 enough to explain the stark contrast in obesity rates, says Mozaffarian.
Still, the changing trend may reflect a real turning point in the country鈥檚 obesity epidemic. More than in the US are eligible for semaglutide. As such, obesity rates will probably continue to fall as more of them start taking the drug.
鈥淚f one-third of our population uses [semaglutide], it will definitely reduce obesity,鈥� says Mozaffarian. 鈥淲e鈥檒l also break the bank. We can鈥檛 afford it. But we鈥檒l definitely reduce obesity.鈥� A year鈥檚 supply of the drug for treating obesity costs more than $ (拢12,700) without insurance.
Newer, more potent weight-loss medications may drive obesity rates even lower, says Brownstein. One 鈥� tirzepatide, which is sold under the name Zepbound 鈥� was approved in the US and UK in November 2023. It can decrease body weight by up to 21 per cent.
We may have entered a new era in treating obesity, but we can鈥檛 overlook that the recent decline in its prevalence may be partly, or even largely, due to the loss of hundreds of thousands of lives during the covid-19 pandemic. Such a tragedy underscores just how important it is to address the obesity epidemic.
JAMA Health Forum
