Contrary to the popular perception, it’s not the urban populace but their rural counterparts who are playing a bigger role in driving global rise in obesity, said researchers.

These researchers had come to the conclusion after analysing data from a whopping 112 million people in 200 countries, including India, over a period of 30 years.

A consortium of over 1000 scientists led by Majid Ezzati, professor of public health at Imperial College, London, which looked at 2000-odd studies involving a total of over 112 million adults aged 18 years and older, found that obesity has increased more rapidly in the world’s rural areas than in cities.

To do this, the scientists compared the body mass index (BMI), which is determined by dividing weight of a person by height in metre squared, of samples participated in the studies in 1985 and 2017.

The current study was the most comprehensive analysis to date of how BMI is changing in rural and urban areas. It was published in the prestigious journal Nature on Wednesday. The authors of the paper, belonged to a network of health scientists called NCD Risk Factor Collaboration, or NCD-RisC, found that 55 per cent of the global rise in BMI since the 1980s came from rural populations.

“The results of this massive global study overturn commonly held perceptions that more people living in cities is the main cause of the global rise in obesity. This means that we need to rethink how we tackle this global health problem,” said Ezzati in a statement issued by Imperial College.

The authors argued that poor, rural communities may be swapping an ‘undernutrition’ disadvantage for a more general malnutrition disadvantage. They called for an integrated approach to narrow the focus of international aid on undernutrition, and broaden it to enhance access to healthier food in both poor rural and urban communities.

The BMI rose by an average of 2.0 kg/m2 in women and 2.2 kg/m2 in men globally, equivalent to each person becoming 5-6 kg heavier. More than half of the global rise over these 33 years was due to an increase in BMI in rural areas. In some low- and middle-income countries, rural areas were responsible for over 80 per cent of the increase, the scientists said.

In India, the national average of BMI for men (both urban and rural) went up by 2.3 kg/m2 to 21.9 kg/m2 in 2017 from 19.6 kg/m2 in 1985. That of women, on the other hand, increased by 2.4 kg/m2 to 22.1 kg/m2 in 2017 from 19.7 kg/m2 in 1985. The rise in BMI among rural men and women on an average was 2.6 kg/m2 and 2.5 kg/m2 respectively during the corresponding period.

The team found important differences between high-, middle-, and low-income countries. In high-income countries, the study showed that the BMI has been higher in rural areas since 1985, especially for women. Researchers attributed this to the disadvantages experienced by those living outside cities: lower income and education, limited availability and higher price of healthy foods, and fewer leisure and sports facilities.

Rural areas - in low and middle-income countries - have a seen shifts towards higher incomes, better infrastructure, more mechanised agriculture and increased car use, all of which bring numerous health benefits. But this shift also led to lower energy expenditure and a hike in expenses on food , which is processed and low-quality when sufficient regulations are not in place. All these factors contribute to a faster increase in BMI in rural areas.

“As countries increase in wealth, the challenge for rural populations changes from affording enough to eat, to affording good quality food,” Ezzati observed.