Do we have the wrong idea about the global obesity 'epidemic?'
Previous research has suggested that urbanization is a primary factor in the rise in obesity around the world. However, a new large-scale study contradicts this, indicating that the increase in obesity rates is more significant among people in rural areas.
Past studies have suggested that, at a global level, urbanization is a key contributor to the soaring rates of obesity.
Researchers have explained this pattern by hypothesizing that people living in urban areas eat more unhealthful, highly processed foods and live less physically active lifestyles.
However, a major new study — the results of which appear in the journal Nature — now turns this idea on its head by showing that obesity rates across the world have grown more rapidly in rural areas than in urban areas.
In the study, researchers from the Imperial College London in the United Kingdom led a global team of more than 1,000 specialists. Together, they analyzed the health data of more than 112 million adults from 200 countries and territories, covering a period of 32 years from 1985 to 2017.
The team sourced these data from 2,009 population-based studies that made their participants' height and weight measurements available. From these two values, it is possible to calculate a person's body mass index (BMI), which allows healthcare professionals to determine whether or not the individual has obesity.
To make sure that their final results were as reliable and unbiased as possible, the researchers excluded data that participants had self-reported.
'Commonly held perceptions overturned'
The investigators' extensive analysis revealed that women's BMI increased by an average of 2.0 kilograms per square meter (kg/m2) over the study period, while men's BMI rose by 2.2 kg/m2 on average.
However, the increases in BMI were most prominent not in urban areas but in rural ones, according to the researchers. They note that rural areas in low- and middle-income countries actually accounted for more than 80% of the BMI increase.
The team explains that the situation has changed since 1985 when in most countries, people living in urban areas had higher rates of obesity than those in rural areas.
Between 1985 and 2017, the average BMI in rural regions worldwide rose by 2.1 kg/m2 for adults of both sexes, whereas in urban areas, the average BMI of women and men increased by 1.3 kg/m2 and 1.6 kg/m2 respectively.
"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."
-Senior author Prof. Majid Ezzati, Imperial College London
At the same time, the researchers note that the income of a country plays a role in the average BMI increase of its population. In high-income countries, BMIs have grown the most in rural areas, especially in the case of women.
The authors believe that this might be because rural populations in high-income countries typically enjoy fewer benefits than their urban counterparts, having lower incomes, more restricted access to education, and less access to healthful foods due to high costs.
"Discussions around public health tend to focus more on the negative aspects of living in cities," notes Prof. Ezzati. "In fact, cities provide a wealth of opportunities for better nutrition, more physical exercise and recreation, and overall improved health."
"These things are often harder to find in rural areas," he emphasizes.
