A comprehensive new report estimates that the proportion of the global population who are overweight or obese has doubled since 1990.

Forward projections to 2050 estimate a further increase, to around 60 percent of those over 25 and more than 30 percent of children and young adults.

As part of the Global Burden of Disease Study 2021, which is funded by the Bill and Melinda Gates Foundation, the analysis modeled overweight and obesity rates from 1990 to 2021. The forecast to 2050 assumes the current trends hold.

“If we act now, preventing a complete transition to global obesity for children and adolescents is still possible,” says Jessica Kerr, obesity epidemiologist at the Murdoch Children’s Research Institute in Australia.

“This is no time for business as usual.”

Two reports were produced: one focused on adults aged 25 or over in 204 countries, using data from 1,350 unique sources. The second studied children and adults under 25, using 1,321 sources from 180 countries.

Body mass index (BMI) was the main metric used for the adults, with overweight defined as a BMI of 25 kg/m² to under 30 kg/m², and obesity defined as anything higher than that.

Alarmingly, the study found that the rates of overweight and obesity increased in all nations, ages, and sexes since the 1990s. The number of adults with overweight or obesity worldwide grew from 731 million in 1990 to 2.11 billion in 2021.

Both sexes saw proportional obesity rates more than double in that time – from 5.8 to 14.8 percent of adult men, and 10.2 to 20.8 percent of adult women.

China had the largest population of adults with overweight or obesity in 2021 with 402 million, followed by India at 180 million and the US at 172 million. However, the fastest-growing prevalence was seen in north Africa and the Middle East, where obesity rates more than doubled in women and tripled in men between 1990 and 2021.

Among children and young adults, obesity prevalence tripled worldwide, growing to 93.1 million individuals aged 5 to 14 years, and 80.6 million aged 15 to 24. The highest increases were seen in southeast Asia, east Asia, and Oceania.

“The drivers of the obesity epidemic are complex. A country’s increasing obesity rates often overlap with their increasing economic development,” the authors write in The Conversation.

“Economic development encourages high growth and consumption. As local farming and food supply systems become overtaken by ‘big food’ companies, populations transition to high-calorie diets.

“Meanwhile, our environments become more ‘obesogenic,’ or obesity-promoting, and it becomes very difficult to maintain healthy lifestyles because we are surrounded by very convenient, affordable, and addictive high-calorie foods.”

If these trends continue unchecked, the report predicts that some 3.8 billion adults globally will be overweight or obese by 2050 – around 60 percent of the projected population of that time.

Obesity alone will affect around 30 percent of the adult population by then, with the highest regional levels expected in the United Arab Emirates, with over 80 percent of men and 87 percent of women in Tonga and Egypt.

Meanwhile, 746 million children, adolescents, and young adults up to the age of 24, or 31 percent of their population, will be affected by obesity by 2050.

The data show that later generations are gaining weight faster than their ancestors – in high-income regions, just 7.1 percent of men and 8.4 percent of women born in 1960 were obese by age 25.

For those born in 1990, that rose to 16.3 percent for men and 18.9 percent for women, and it’s expected that by the time the 2015 cohort turns 25, obesity will affect 25.1 percent of its men and 28.4 percent of its women.

This drastic increase in overweight and obesity will also increase rates of associated diseases, like type 2 diabetes, cardiovascular disease, and some types of cancers.

Fortunately, the authors state that there is still time to act, although it must be done quickly. Governments around the world should implement five-year action plans that involve nutrition education, better transportation and ‘walkability’ infrastructure, and regulation of ultra-processed foods.

Walking and cycling get 90c per person each year from the Australian government. What if that figure rose to $5, $10 or $15? @HealthTepi @MonashUni @uwanews @UNSW https://t.co/YfjKlIH0JD

— The Conversation – Australia + New Zealand (@ConversationEDU) February 3, 2025

“Many countries only have a short window of opportunity to stop much greater numbers shifting from overweight to obesity,” says Kerr.

“Ultimately, as global obesity rates continue to soar, much stronger political commitment is needed to transform diets within sustainable global food systems and to support comprehensive strategies that improve people’s nutrition, physical activity, and living environments, whether it’s too much processed food or not enough parks.”

There are of course some caveats to the claims. BMI is far from a perfect measure of health, since it doesn’t account for muscle mass or natural variations in different ethnic groups.

The studies also rely on self-reported data, which can contain biases. And the projections don’t account for new technologies such as the rise of semaglutide drugs for weight loss.

Regardless, action plans for better public health can only be a good thing.

The studies were published in The Lancet.