Obesity is spreading more rapidly in the world’s rural areas than in cities, according to a new study by an international team of researchers. Finland, however, makes an exception to this trend, as obesity is more common among the country’s city dwellers than in the countryside. In Finland, the average body mass index (BMI) is slightly higher than elsewhere in the world; however, the study shows that the rest of the world is quickly catching up.
Published in Nature, the study analysed global trends in BMI. A network of more than 1,000 researchers from all over the world analysed height and weight data from more than 112 million adults across urban and rural areas of 200 countries and territories between 1985 and 2017. Finland was represented in the study by 34 cohorts involving 41,000 men and 30,000 women. One of the cohorts included in the study was the Kuopio Ischaemic Heart Disease Risk Factor Study, KIHD, ongoing at the University of Eastern Finland.
BMI is used to assess whether an individual has a healthy weight for their height. BMI is calculated by dividing an individual’s weight (kg) by their height in metres squared (m2). An individual is considered to be overweight when their BMI is above 25. In 2017, the average age-standardised BMI of Finnish men was 26.4, and that of women 25.4. Since 1985, BMI has increased by 1.2 units in men and by 0.9 units in women. The average global BMI was 24.7 in men and 24.4. in women. From 1985 to 2017, BMI rose by an average of 2.2 units in men and 2.0 units in women globally, equivalent to each person becoming 5-6 kg heavier.
Finnish city dwellers’ BMI increased more
Globally, rural areas were responsible for over 80 per cent of the increase in BMI in some low- and middle-income countries. Since 1985, the average BMI in rural areas has increased by 2.1 units in both women and men, but in cities, the increase was 1.3 units and 1.6 units in women and men respectively.
In Finland, people living in rural areas had a slightly higher BMI than their counterparts living in cities both at the beginning and end of the study; yet city dwellers gained more weight during the follow-up. In 2017, the average BMI in men was 26.6 in in rural areas and 26.3 in cities. Since 1985, men's BMI has increased by 1.1 units in rural areas and by 1.2 units in cities. The average BMI of women was 25.9 in rural areas and 25.3 in cities. Since 1985, women’s BMI has increased by 0.7 units in rural areas and by 1.0 units in cities.
Global obesity epidemic spreads to rural areas
In 1985, urban men and women in more than 75 per cent of the countries had a higher BMI than their rural counterparts. Over the past three decades, however, the gap between urban and rural BMI in many of these countries has shrunk or even been reversed.
In high-income countries, BMI has been generally higher in rural areas since 1985, especially for women. According to the researchers, this may be due 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. Meanwhile, rural areas in low- and middle-income countries have witnessed an increase in BMI. This is due to a rapid shift towards higher incomes, better infrastructure, more mechanised agriculture and less physical work.
Professor Tomi-Pekka Tuomainen from the University of Eastern Finland Institute of Public Health and Clinical Nutrition notes that the findings challenge the idea of obesity being linked to urbanisation.
“We are seeing two separate, yet simultaneous trends: urbanisation and BMI rise. It is easy to conclude that the population-level rise in BMI is caused by the transition from rural areas to urban ones. However, this new study now shows that BMI is rising even faster outside cities, and that the traditional gap in favour of rural areas is shrinking. Obesity is a growing health concern everywhere, not just in growth centres and urban settings.”
“In Finland, the gap between rural and urban areas is smaller than in many other countries. Here, differences in educational level and health awareness are not as great as in many other countries, and people are aware of health-promoting lifestyles regardless of where they live. In Finland, people can eat healthy food throughout the year even in rural areas and small towns,” Docent Sari Voutilainen notes.
Differences and changes in BMI across the world
- Nationally, BMI decreased slightly between 1985 and 2017 among women in Greece, Spain, Lithuania, Czech Republic, Italy, Portugal, Serbia, France, Malta, Nauru, Singapore and Japan. At the other extreme, it increased by more than 5 units in women in Egypt and Honduras.
- Among men, BMI increased in every country, with the largest increases in Saint Lucia, Bahrain, Peru, China, Dominican Republic and the USA, all by more than 3.1 units.
- Rural women in Bangladesh had the lowest BMI recorded in the study in 1985, at 17.7. Men living in rural Ethiopia had the lowest male BMI at 18.4.
- Urban women from the US South Pacific territory of American Samoa had the highest BMI recorded, at 35.4 kg/m2 in 2017. Rural men from the same country were highest for males, at 34.6 kg/m2 also in 2017.
For further information, please contact:
Professor Tomi-Pekka Tuomainen, University of Eastern Finland, Institute of Public Health and Clinical Nutrition, tel. +358 403552956, tomi-pekka.tuomainen (a) uef.fi
Docent Sari Voutilainen, University of Eastern Finland, Institute of Public Health and Clinical Nutrition, tel. +358403552786, sari.voutilainen (a) uef.fi
Research article:
Rising rural body-mass index is the main driver of the global obesity epidemic. NCD Risk Factor Collaboration (NCD-RisC). Nature 9.5.2019.
Further information on the NCD-RisC project and a visualisation of the data are available at: http://www.ncdrisc.org/