Obesity has often been thought of as a problem of the developed world, with wealthy countries eating themselves into a state of ill-health with an abundance of ultraprocessed foods, and poorer ones more often suffering from food insecurity. But that’s no longer true. According to a March report from the World Obesity Atlas (WOA), more than half of the global population—51%, or over 4 billion people—will have obesity by 2035, and the condition will touch all regions and continents of the world. The total cost of treating illnesses related to obesity will be an estimated $4 trillion per year, which is about how much the COVID-19 pandemic cost the world in health care expenses in 2020.
The new projection marks a sharp jump from current 2023 numbers. Right now, about 3.12 billion people (39% of the global population) have obesity. But 15 years ago, in 2008, the global obesity rate was 23.9%, affecting 1.63 billion people.
The WOA, a non-governmental organization which files its reports with both the World Health Organization and the U.N., surveyed current obesity rates and trends in 180 different countries to arrive at its newly projected figures. The nations with the highest obesity rates tend to cluster in the South Pacific, with Kiribati and Tonga leading the world in projected 2035 obesity rates at 67%, followed by Samoa at 66%, French Polynesia at 65%, and Micronesia at 64%. The U.S. registers near the top, with a rate of 58%. The lowest projected obesity rates are found in Asia, with Vietnam at 7%, followed by Japan at 8%, Singapore at 9%, and both India and Bangladesh at 11%.
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Especially affected by the growing epidemic will be children ages 5-19, in whom obesity rates are predicted to double, climbing from 10% to 20% for boys and 8% to 18% for girls. Even in Southeast Asia, with its relatively low projected obesity rates, weight gain in the youngest cohort is expected to be significant, with obesity rates among boys increasing from 5% to 16% and in girls from 3% to 11%. In the South Pacific, a bad problem will likely only grow worse, as boys are predicted to go from a 19% obesity rate to 41% and girls to climb from 9% to 28%. The Americas will see their numbers grow as well, with the share of obese boys rising from 20% to 33% and girls climbing from 16% to 26%.
The WOA posits a lot of causes for the current trend beyond the growing global popularity of cheap, highly processed Western style food. Also to blame are so-called obesogens, or chemical pollutants like bisphenol A (BPA) that act as endocrine disruptors and are found in plastics, food packaging, household furnishings, paints, cosmetics, and more. Things only get worse when obesogens and poor diet co-occur.
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“The increase in ultraprocessed foods in countries globally, particularly lower-middle income countries,” the report states, “is likely to increase plastic-based products [in food packaging] and plastic waste. In turn, the exposure to obesogenic pollutants may rise rapidly.”
That is only part of the report’s discouraging takeaway. “Every nation is affected by obesity, with some lower income countries showing the highest increases in the last decade,” the authors write. “No country has reported a decline in obesity prevalence across their entire population. While preventing and treating obesity requires financial investment, the cost of failing to prevent and treat obesity will be far higher.”
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Write to Jeffrey Kluger at jeffrey.kluger@time.com