The height and weight of school-age children, which are indicators of their health and quality of diet, shows significant variation around the world.
A new global study led by researchers at Imperial College London collaborates this fact, and urges schools and policy-makers to initiate urgent remedial measures to ensure a healthier future population.
The researchers analyzed height and weight data of 65 million children aged five to 19 years old in 193 countries. The study found that there was an enormous 20cm difference between 19-year-olds in the tallest and shortest nations.
The finding represented an eight-year growth gap for girls, and a six-year growth gap for boys. For instance, the study revealed that the average 19-year-old girl in Bangladesh and Guatemala (the nations with the world’s shortest girls) is the same height as an average 11-year-old girl in the Netherlands, the nation with the tallest boys and girls.
The international team behind the study warned that highly variable childhood nutrition, especially a lack of quality food, may lead to stunted growth and a rise in childhood obesity that affects a child’s health and wellbeing for their entire life.
The research, which reported data from 1985 to 2019, revealed that the nations with the tallest 19-year-olds in 2019 were in northwest and central Europe, and included the Netherlands, Montenegro, Denmark and Iceland.
These nations with the shortest 19-year-olds in 2019 were mostly in south and southeast Asia, Latin America and East Africa, including Timor-Leste, Papua New Guinea, Guatemala and Bangladesh.
The largest improvements in average height of children over the 35-year period were seen in emerging economies such as China, South Korea and some parts of southeast Asia. For example, 19-year old boys in China in 2019 were 8cm taller than in 1985, with their global rank changing from 150th tallest in 1985 to 65th in 2019. In contrast the height of children, especially boys, in many Sub-Saharan African nations has stagnated or reduced over these decades.
The study also assessed children’s Body Mass Index (BMI) — a measure of height to weight ratio, which gives an indication of whether a person has a healthy weight for their height. The analysis found that 19-year-olds with the largest BMI were found in the Pacific islands, Middle East, USA and New Zealand. The BMI of 19-year-olds was lowest in south Asian countries such as India and Bangladesh. The difference between the lightest and the heaviest BMIs in the study was around 9 units of BMI (equivalent to around 25 kg of weight).
The research team said their analysis also revealed that, in many nations, children at age five had a height and weight in the healthy range defined by the World Health Organization (WHO). However, after this age, children in some countries were found to have experienced too small an increase in height, and gained too much weight, compared to the potential for healthy growth.
The team say the most important reason for this is the lack of adequate and healthy nutrition and living environment in the school years, as both height and weight gains are closely linked to the quality of a child’s diet.
This shows that there is an imbalance between investment in improving nutrition in pre-schoolers, and in school-aged children and adolescents. This issue is especially important during the COVID-19 pandemic when schools are closed throughout the world, and many poor families are unable to provide adequate nutrition for their children, said the researchers.
The scientists called for policies that increase the availability and reduce the cost of nutritious foods, through initiatives such as free healthy school meal programs and food vouchers for nutritious foods for low-income families. This would help children grow taller without gaining excessive weight for their height, and provide lifelong benefits for their health and wellbeing.