By William Wan

The Washington Post

As the rate of obesity around the world has climbed steadily for decades, public health efforts to combat it have largely focused on people in cities. With growing numbers of people living in cities, the assumption by public health officials was that urbanization — with its sedentary lifestyle and easy access to highly processed foods — was driving much of the weight gain.

But a growing body of research suggests the bigger problem is in rural areas.

On Wednesday, a consortium of researchers released the most comprehensive studies to date on regional obesity rates, showing that the global rise in obesity in the past three decades has been driven more by unhealthy weight gain in rural areas than in urban ones. The study — a massive collaboration by more than 1,000 researchers, drawing on more than 2,000 studies of 200 countries — found that more than 55% of the global increase in body mass index in the past 30 years has come from rural populations. The trend was even sharper in low- and middle-income countries, with more than 80% of the worsening BMI driven by rural populations.

The researchers found that in almost every region around the world, weight gain in rural areas is increasing at the same rate or faster than in cities.

The findings have profound implications as countries struggle to control health risks from the global obesity epidemic.

Instead of focusing mostly on city-specific programs — such as building bike lanes to encourage exercise or trying to get more fresh produce into urban areas — rural solutions are needed as well, health researchers say.

“It means we need to think of policies that address rural areas or have an effect in rural and urban areas equally. We can’t just ignore it anymore,” said Barry Popkin, a food science researcher at the University of North Carolina who was not involved in the study.

Researchers say the same trends seen in the cities — increasingly sedentary lifestyles and consumption of unhealthy foods — have penetrated the rural areas quickly and widely.

Development in rural areas has improved the quality of life dramatically, but it also has changed people’s bodies.

“There is now running water in homes where before people had to fetch water,” said senior author Majid Ezzati, a global health researcher at Imperial College in London. “You have cars and tractors. … There is less physical labor, less energy expenditure.”

The sprawling nature of rural areas makes it harder and more costly to implement public health interventions that work in cities, and the efforts are often complicated by lack of basic infrastructure.

According to the World Health Organization, obesity has nearly tripled since 1975. In 2016, more than 1.9 billion adults were considered overweight. Of those, over 650 million were obese. In the United States, obesity is more prevalent among those living in rural counties, at 34.2%, than among those living in metropolitan counties, at 28.7%, according to the Centers for Disease Control and Prevention.