A global analysis of trends in child and adolescent height and body mass index (BMI) led by the Imperial College London and published in the scientific journal Nature in March showed that the urban height and nutrition advantage shrank in most countries, while children and adolescents in rural areas showed accelerated height improvements. “Children growing up in cities did not show the expected growth. Children living in rural areas have caught up with city kids, both in height and weight.
So, kids growing in rural areas are showing a healthier growth trend,” says senior diabetologist , who was one of the co-authors of the study. Rural areas are catching up to cities mainly because of improvements in sanitation, nutrition and healthcare, . While there has been a worldwide increase in height and BMI since 1990, the researchers found the degree of change between urban and rural areas varied greatly among middle and low income countries.
“In the 1990s, India had one of the largest gaps between urban and rural BMI — 0.72 kg/ m2 difference – in girls. However, the BMI of successive cohorts of children and adolescents increased more in rural areas than in cities, leading to a moderate closing of the urban-rural difference,” says a senior diabetologist, who is a co-author of the study. The study was done by a global consortium of more than 1,500 researchers and physicians where scientists analysed height and weight data from 71 million children and adolescents aged between 5 and 19 years across urban and rural areas of 200 countries from 1990 to 2020. While nutrition deficiencies, stunted growth and malnourishment declined rapidly in rural areas, India has seen substantial increases in height over the last two decades — around 4cm for both boys and girls, he says.
“There is a modest decrease in the urban height advantage in both sexes.” The researchers found that by 2020, averages rose for most countries. In sub-Saharan Africa and South Asia, the BMI rose faster in rural areas. In India, there is a substantial difference between urban and rural areas, but this is more pronounced in some states. Not all states are at the same level of socioeconomic development, says diabetologist who co-authored the study. “In Kerala, we found that the rural prevalence of diabetes, obesity and dyslipidemia was not very different from that seen in urban parts of the state. While urbanisation has its advantages, there is also a sharp socio-economic divide and for those who are relatively affluent, life in the city is beneficial.
The living conditions of people in urban slums – amidst open defecation, crowding and unemployment — are often worse than in rural areas,” he says. Children living in city slums are fighting with risk of infectious diseases and are drawn into unhealthy lifestyles including poor diet and lack of exercise. “They don’t have enough space to play. They choose cheap junk food over healthier options such as legumes, vegetables, fruit and nuts. They are exposed to higher levels of pollution. Such an environment destroys all benefits of health and education that can be accessed by a child growing up in a city. This is why a child in the city tends to be one of two extremes — undernourished or obese,” .
Earlier studies by the research organisation he heads, the Madras Diabetes Research Foundation, have shown rural-to-urban migration is associated with an increased risk of developing diabetes and cardiometabolic abnormalities even among adults. A 2021 ICMR–INDIAB study on diabetes and associated cardiometabolic disorders in individuals aged at or above 20 years from India analysed data of people who moved to a different place from their place of birth. The study showed that the prevalence of diabetes was 14.7% in ruralurban migrants, followed by urban dwellers (13.2%), urban-rural migrants (12.7%) and rural dwellers (7.7%).
“A person residing in the city has less chance of getting lifestyle disorders compared to a person who has moved into the city from a rural area. The risk for diabetes was 1.9 times higher in rural-urban migrants than among rural dwellers,” says Dr Mohan. Rural urban migrants also have the highest prevalence of abdominal obesity (50.5%) compared to the other three groups. “They tend to be less physically active. Also, they do not add enough fruit and vegetables to their diet.”