Projecting Global Trends and Inequalities in Adult Overweight and Obesity, 2023–2040: Findings From the NCD-RisC Database

Objective: This study quantifies the global burden of overweight and obesity, projects future trends, and examines associated health inequalities. Methods: Overweight and obesity burden data were obtained from the NCD-RisC database. Trends from 1990 to 2022 were analyzed, and a Bayesian model was used to project changes for 2023–2040. Cross-national health inequalities were measured using the slope index of inequality (SII) and the relative concentration index (RCI). Results: Globally, overweight prevalence rose from 17.50% in 1990 to 28.00% in 2022 (average annual percentage change [AAPC] = 1.48%) and is projected to reach 43.97% by 2040 (AAPC = 1.13%). Obesity prevalence grew from 6.44% to 16.06% (AAPC = 2.46%) and is projected to surge to 38.96% by 2040 (AAPC = 4.96%). The SII for overweight burden dropped from 33.74% in 1990 to 16.24% in 2022, and it is projected to reverse to −2.42% by 2040. For obesity (BMI, ≥ 30.0 kg/m²) and mild obesity (BMI, 30.0–34.9 kg/m²), the SII declined from 20.12% to 18.58% and from 14.22% to 10.02%, respectively, with further drops to 9.35% and −1.70% by 2040. From 1990 to 2040, the share of the global prevalence burden of overweight and obesity in countries with the lowest GDP per capita rose from 15% to 22% and from 6% to 26%, respectively. The relative gradient inequality, measured by RCI, also showed similar findings. Conclusions: The global burden of overweight and obesity has significantly increased from 1990 to 2040. Health inequalities decreased from 1990 to 2022, with the burden mainly in higher-income countries. However, by 2040, the burden of overweight and mild obesity is projected to shift to lower-income countries, highlighting the need for targeted health policies and interventions.