The total of people worldwide living with obesity has passed one billion, indicating a growing epidemic that spans both adults and children, a study has shown.

The study, published on Thursday in The Lancet medical journal, involved the World Health Organisation and more than 1,500 scientists worldwide.

Majid Ezzati of Imperial College London's School of Public Health voiced deep concerns about escalating obesity rates among school-aged children and adolescents, mirroring the epidemic seen in adults since 1990.

He said that to “successfully tackle both forms of malnutrition, it is vital we significantly improve the availability and affordability of healthy, nutritious foods”.

The study analysed data on weight and height of almost 220 million people from 190 countries.

The study's findings reveal a startling quadrupling of obesity rates for adults more than doubled between 1990 and 2022, and more than quadrupled among children and adolescents aged 5-19, the paper said.

This puts the total number of children or adolescents and adults living with obesity in 2022 at 159 million and 879 million, respectively.

Mr Ezzati called the rise in obesity rates among children “very concerning”, mirroring a trajectory seen with adults since even before 1990. At the same time, he said, hundreds of millions still do not have enough to eat.

Despite a reduction in underweight proportions among children, adolescents and adults over the past 33 years, the study highlights uneven progress across different regions.

The Middle East, North Africa and various island nations in the Pacific and the Caribbean emerged as the regions with the highest combined rates of underweight and obesity, passing even the obesity rates of many high-income industrialised countries in Europe.

The high rates of obesity continue to grow in the US, with recent data showing a major increase, from 21.2 per cent in 1990 to 43.8 per cent in 2022 among women, and from 16.9 per cent to 41.6 per cent among men.

This surge has put the US at 36th globally for female obesity rates and an alarming 10th highest for men as of 2022.

In contrast, India's obesity rates, while on the rise, paint a different picture on the global scale.

Women's obesity rates have climbed from a mere 1.2 per cent in 1990 to 9.8 per cent in 2022, and men's from 0.5 per cent to 5.4 per cent.

Despite this increase, India's obesity prevalence remains among the lowest worldwide.

Mr Ezzati said potent new obesity drugs like Novo Nordisk's Wegovy and Eli Lilly's Mounjaro and Zepbound were tools that may help, but their cost and low availability risked further increasing inequality.