Worldwide trends in underweight and obesity from 1990 to 2022: A pooled analysis

This study pooled data from 3,663 population-based studies with measurements of height and weight involving 222 million participants across 200 countries and territories, to provide an analysis of global trends in underweight and obesity over a period of 32 years (1990-2022). The primary outcomes were individual and combined prevalence of underweight (adults; age ≥20 years) or thinness (school-aged children and adolescents aged 5-19 years) and obesity. Because cutoffs for underweight and obesity differ between these two age groups, analysis was done separately for adults and for children and adolescents. Underweight was defined as a body mass index (BMI) of less than 18.5 kg/m2 and thinness as BMI less than two standard deviations (SD) below the median of the World Health Organization (WHO) growth reference. Obesity was defined as a BMI of 30 kg/m2 or higher for adults and a BMI of more than two SD above the median of the WHO growth reference for children and adolescents.

Globally, the study found that, while underweight prevalence had decreased, obesity had increased. This led to an increase in the combined (double) burden in most countries, with some exceptions in south and southeast Asia and in sub-Saharan Africa. By 2022, obesity was more prevalent than underweight in many of the countries, with a significant increase in the combined burden in 162 countries for women and in 140 for men.

Regionally, in 2022 the highest combined prevalence of underweight and obesity was observed in island nations in the Caribbean, Polynesia, and Micronesia and countries in the Middle East and North Africa. The obesity prevalence in these countries in 2022 was higher than in high-income countries. In south Asia, despite a reduction in underweight, the combined prevalence remains high, especially in countries like India and Pakistan where both thinness and obesity are prevalent.

Age wise, adult underweight was more prevalent than obesity in 65 countries for women and in 89 countries for men in 1990. By 2022, obesity had increased and become more dominant in 177 countries for women and in 145 for men. Among school-aged children and adolescents, the prevalence of thinness has decreased in some regions, but obesity had increased globally.

While efforts to reduce underweight have seen some success, the rapid increase in obesity presents a new challenge, particularly in low- and middle-income countries. The article highlights the growing double burden of malnutrition, driven primarily by an increase in obesity. These trends make it necessary for urgent action and attention from policymakers to implement strategies that address both underweight and obesity, with a focus on promoting healthy dietary practices globally and improving access to nutritious foods. There is an urgent need for obesity prevention, as well as tackling the remaining burden of undernutrition especially in south and southeast Asia and parts of Africa.