Exposing the Global Battle Against Underweight and Obesity: Key Findings from a Landmark Research Paper with 222 Million Participants Worldwide

A very important research paper was published a few days ago by NCD-RisC (a network of health scientists around the world) in the world’s leading general medical journal, The Lancet. This groundbreaking study aimed to analyze the worldwide trends in underweight and obesity from 1990 to 2022, employing a pooled analysis of 3663 studies encompassing a staggering 222 million participants across 200 countries and territories.

In the era of rapid globalization and an ever-evolving food landscape, understanding the trends and prevalence of underweight, thinness, and obesity becomes crucial in combating global health issues. This study takes a comprehensive approach by using thousands of high-quality population-based studies to examine the combined burden of these conditions, as well as the impact of changes in food policies and programs. By presenting consistent and up-to-date estimates from late childhood to adulthood for all countries in the world, this study sheds light on the changing dynamics of global nutrition.

Introduction

Underweight and obesity are two significant health concerns that have far-reaching impacts on individuals’ well-being and overall health outcomes. In the review of this research paper, we delve into the prevalence of underweight and obesity among adults, school-aged children, and adolescents in various countries and territories worldwide. Drawing from extensive data gathered over three decades, the authors shed light on changing prevalence rates and highlight key regional variations. This article aims to underscore the importance of addressing these pressing issues through healthy nutrition transitions to combat obesity while ensuring access to nutritious foods to tackle underweight concerns.

Methods

To provide accurate insights, the authors analyzed data collected from 3663 population-based studies encompassing 222 million participants. These studies involved measuring height and weight in representative samples of the general population. They employed a Bayesian hierarchical model to estimate prevalence trends for different Body Mass Index (BMI) categories among adults (age ≥20 years) and school-aged children and adolescents (age 5–19 years). Specifically, they reported individual and combined prevalence rates of underweight (BMI <18·5 kg/m2) and obesity (BMI ≥30 kg/m2) for adults, while focusing on thinness (BMI <2 SD below the median of the WHO growth reference) and obesity (BMI >2 SD above the median) for school-aged children and adolescents.

Prevalence of Underweight and Obesity

Between 1990 and 2022, the combined prevalence of underweight and obesity demonstrated varied trends worldwide. Notably, the authors observed a decrease in the combined prevalence of underweight and obesity in 11 countries (6%) among women and 17 countries (9%) among men, with a posterior probability of at least 0·80 validating the observed changes as true decreases. Conversely, in 162 countries (81%) among women and 140 countries (70%) among men, the combined prevalence significantly increased, backed by similar levels of posterior probability. In 2022, island nations in the Caribbean, Polynesia, and Micronesia, as well as countries in the Middle East and North Africa recorded the highest combined prevalence of underweight and obesity. It is worth noting that obesity prevalence surpassed underweight prevalence in most countries, establishing this trend globally and within specific regions.

Regional Variations

Significant regional disparities emerged when considering the combined burden of underweight and obesity. Island nations in the Caribbean, Polynesia, and Micronesia, along with countries in the Middle East and North Africa, exhibited the highest prevalence rates. These regions possess unique socio-economic and cultural factors that contribute to the observed patterns. Furthermore, discrepancies between prevalence rates among men and women were evident, with the posterior probability indicating significant differences in 177 countries (89%) for women and 145 countries (73%) for men in 2022. However, in specific countries (16 for women and 39 for men), underweight prevalence exceeded obesity rates.

Age-standardised combined prevalence of underweight and obesity by country, for adults (age ≥20 years)

Proportion of the double burden from obesity, for adults (age ≥20 years)

Trends in School-Aged Children and Adolescents

Analyzing data specific to school-aged children and adolescents, intriguing trends emerged from 1990 to 2022. The combined prevalence of thinness and obesity significantly decreased among girls in five countries (3%) and among boys in 15 countries (8%), with a posterior probability exceeding 0·80. Conversely, an increase in the combined prevalence of thinness and obesity was observed in 140 countries (70%) among girls and 137 countries (69%) among boys, supported by a similar level of posterior probability. In 2022, Polynesia, Micronesia, the Caribbean, Chile, and Qatar displayed the highest combined prevalence of thinness and obesity in this population.

Prevalence among Boys and Girls

Examining the prevalence of thinness and obesity separately for boys and girls revealed noteworthy distinctions. Obesity showed a higher prevalence compared to thinness, as established by a posterior probability of at least 0·80 among girls in 133 countries (67%) and boys in 125 countries (63%). Conversely, thinness prevalence exceeded obesity rates in 35 countries (18%) among girls and 42 countries (21%) among boys. These variations accentuate the contrasting health challenges faced by boys and girls and highlight the necessity for targeted interventions.

Age-standardised combined prevalence of thinness and obesity by country, for school-aged children and adolescents (age 5–19 years)

Proportion of double burden from obesity for school-aged children and adolescents (age 5–19 years)

Double Burden and its Drivers

The concept of the double burden refers to populations experiencing the coexistence of underweight and obesity. Across most countries, the increase in the double burden was primarily driven by rising obesity rates, while declining underweight or thinness contributed to a decrease in the double burden. This suggests that while obesity remains prevalent on a global scale, underweight continues to pose a significant challenge, particularly in regions like South Asia and certain parts of Africa. Addressing the double burden necessitates a comprehensive and holistic approach that emphasizes nutrition and access to healthy foods.

Implications and Recommendations

The findings of this study underscore the urgency of addressing the combined burden of underweight and obesity. As obesity rates rise in most countries, underweight and thinness persist, particularly in South Asia and select African regions. This study emphasizes the importance of a healthy nutrition transition that not only curbs the increase in obesity but also addresses the enduring burden of underweight. Promoting access to nutritious foods is paramount for fostering healthy weight management and overall well-being.

Conclusion

In conclusion, this landmark paper elucidates the changing prevalence of underweight and obesity among adults, school-aged children, and adolescents across different countries and territories from 1990 to 2022. Significantly, regional variations highlight certain areas grappling with a greater burden of underweight and obesity. While overall obesity rates have increased, the persistence of underweight in specific regions necessitates a comprehensive approach to nutrition and health.

To access the original publication click HERE.