Background <p>Anorexia nervosa is a severe psychiatric disorder with high morbidity and mortality. Traditionally linked to high-income regions, its recognition is growing in low- and middle-income countries. This study analyzes the global, regional, and national burden of anorexia nervosa from 1990 to 2021 using GBD 2021 data and offers projections to 2040.</p> Methods <p>Data on the prevalence, years lived with disability (YLDs), and age-standardized rates of anorexia nervosa were obtained from the GBD 2021 study, covering 204 countries and regions. The study used various statistical methods, including the Assessment of Health Inequalities, Frontier Analyses, Temporal Trend Analysis and Bayesian Age-Period-Cohort (BAPC) model, to analyze trends, regional disparities, and forecast future disease burden. Results were stratified by Socio-Demographic Index (SDI) regions, age, and gender.</p> Results <p>From 1990 to 2021, the global prevalence of anorexia nervosa increased by 38.79%, with YLDs rising by 38.57%. High-SDI regions consistently showed the highest burden of the disorder, with significant increases in both prevalence and YLD rates. In contrast, low-SDI regions exhibited lower burdens, likely reflecting underreporting and diagnostic challenges. Female populations continued to bear a higher burden than males, although the prevalence of anorexia nervosa among males has steadily increased. Forecasts to 2040 predict continued increases in disease burden, particularly among females.</p> Conclusions <p>Anorexia nervosa’s global burden has risen, especially in high-SDI regions. The increasing prevalence, particularly among females, underscores the need for targeted public health interventions, early diagnosis, and culturally appropriate treatments. Projections show continued growth in the disorder’s burden.</p>