A new way of measurement proposed by researchers in Italy could see millions more middle-aged people finding themselves classed as obese.

A study of 4,800 adults aged 40-80 led by the University of Tor Vergata in Rome focuses on body fat percentage, rather than the usually accepted ratio of weight to height known as Body Mass Index, or BMI, which is recognized by the World Health Organization, but does not differentiate between fat, muscle and bone in total weight.

Researchers suggest fat is a more realistic representation because as people age, muscle declines and fat builds up around organs close to the waist region, often without any change in weight.

A BMI of 18.5-25 is regarded as a healthy weight, 25-29 is overweight, and 30 or above is obese.

In the Rome study, just 38 percent of men and 41 percent of women studied had a BMI of more than 30, but when scans were done to specifically look at body fat percentage, 71 percent of men and 64 percent of women were found to qualify as obese.

However, critics of the study say it has only focused on one small geographical region and many potential contributory factors, such as diet and exercise, were not factored in, limiting its relevance to what is a global concern, as issues associated with obesity include type 2 diabetes, coronary heart disease, cancer and stroke.

The World Obesity Federation website lists data about individual countries' obesity rates.

For adult males in China, the obesity rate is 8.94 percent, putting it 149th out of 200 countries, for adult females it is 7.78 percent, in 190th place, and for children it is 7.71 percent, in 102nd place, with a study published in the journal Nature in June 2023 saying that obesity among children under the age of 5 in China is continuing to rise.

In March, the WHO shared data published in the Lancet showing that 9 out of the top 10 places in the world for obesity rates among men and women aged over 20 were in the Pacific region.

Some people are more genetically prone to obesity than others, but lifestyle, exercise and diet are also significant contributory factors, with WHO South Pacific representative Mark Jacob saying it was a complex picture.

"In many parts of the Pacific, unhealthy food is cheap, convenient, and pushed heavily through advertising. Healthy food, on the other hand, may be increasingly difficult to get and more expensive in the face of the droughts, floods and rising seas caused by climate change," he explained.

"What we eat, how much we eat, and whether we are physically active also comes down to things like the culture around us and whether there is a safe and comfortable place to exercise."