More than 1 billion people have obesity, including 159 million young people, study estimates

More than 1 billion people — or one in eight people worldwide — are now estimated to have obesity, a new study finds.

Obesity rates grew particularly fast among children and teens, quadrupling from 1990 to 2022, the latest year the analysis looked at, while rates among adults more than doubled. That comes to 159 million children and teens with obesity, and 879 million adults, according to the study, published Thursday in the Lancet and conducted by the NCD Risk Factor Collaboration, a group of researchers around the world studying noncommunicable diseases.

Obesity is flaring in low- and middle-income countries, the study found. Some of the biggest increases in youth obesity rates occurred in Polynesia and Micronesia and the Caribbean. Latin America and the Middle East and North Africa are also experiencing much more obesity than underweight, the study said.

The new data highlight how the global burden of obesity is evolving. Obesity, and other chronic diseases like diabetes, have traditionally been associated with high-income countries, but they’re increasingly affecting low- and middle-income countries as well, as those regions rapidly shift to industrialized lifestyles with diets of processed foods and reduced physical activity. And after obesity rates started rising among adults over the past few decades, the same trends are now occurring younger in life, among children and teens.

The advent of highly effective GLP-1 based obesity drugs like Wegovy and Zepbound have stoked excitement among many doctors as a new way to address rising obesity rates. But the treatments are costly, have repeatedly fallen into shortages and so far have only launched in a few high-income countries.

“These drugs are definitely an important tool, but they should not be seen as a solution to the problem,” Francesco Branca, director of nutrition and food safety at the World Health Organization, said in a press briefing discussing the study. “The solution still is in the transformation of food systems and the environment, such that obesity can be prevented.”

The shortages and lofty costs of the drugs, which carry prices of over $10,000 annually in the U.S., also risk widening health inequities across the world.

“We should make sure that people who need these the most receive it,” said Majid Ezzati, a professor at Imperial College London who leads the NCD Risk Factor Collaboration. “‘Needing the most’ is both a clinical decision, but also a question for health care systems to make sure that they reach those people without overdue financial burden.”

The analysis was conducted using datasets on people’s height and weight across the world. It defined obesity for adults as having a body-mass index above 30 and underweight as a BMI under 18.5. For children and teens, obesity was defined as being two standard deviations higher than typical growth trends and underweight is two standard deviations below.

A limitation of the study is that it used the same BMI cutoffs to define obesity and underweight across the entire global population, even though emerging data suggest that it might be more suitable to use different cutoffs for each demographic group. For example, South Asian people tend to develop diabetes and heart complications at lower BMIs than white people.

Ezzati said that using the same BMI cutoffs allowed the researchers to easily compare across different populations and BMI was the best measurement that could be analyzed using available data. “The results in terms of the overall global patterns are probably unaffected by the choice of the metric,” he said, but it is important to continue to study how the measurement should be used across different demographics.

The analysis also looked at underweight rates, which fell over the past three decades. Large decreases in youth underweight rates occurred in south and southeast Asia and sub-Saharan Africa, but those regions still have among the highest rates of underweight in the world, the study found.

The authors said it’s important to address the remaining issues of underweight alongside the increases in obesity, especially since populations can rapidly transition from being underweight to overweight, as both are related to having inadequate access to nutritious foods.

“Undernutrition and obesity are two faces of the same problem, which is the lack of access to a healthy diet,” Branca of the WHO said.

He urged officials to adopt policies that can address both, including improving nutrition early in life such as by promoting breastfeeding, regulating food marketing, facilitating physical activity, and providing nutrition services in primary health care.

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