The Global Obesity Epidemic: Epidemiology, Health Burden and Policy Priorities

The global prevalence of obesity has more than tripled since 1975, now affecting nearly one billion adults and over 170 million children and adolescents. In 2025, The Lancet Diabetes & Endocrinology Commission on Clinical Obesity redefined obesity as a chronic, multisystem disease characterised by excess adiposity leading to organ dysfunction, distinguishing between preclinical obesity (excess adiposity without end-organ injury) and clinical obesity (manifest metabolic or structural complications). This framework moves beyond reliance on BMI, acknowledging that ectopic fat deposition in the liver, muscle and viscera is a more accurate determinant of cardiometabolic and hepatic risk. Once considered a disease of affluence, obesity is now increasing most rapidly in rural and low- to middle-income countries, driven by urbanisation of lifestyle, reduced physical activity and the proliferation of ultra-processed foods. The result is a parallel escalation in non-communicable diseases, with obesity underpinning cardiovascular, metabolic, hepatic, renal, respiratory, oncological and psychological disorders, among others. Cardiovascular disease remains the leading cause of obesity-related mortality, while type 2 diabetes, metabolic dysfunction-associated steatotic liver disease and chronic kidney disease contribute substantially to morbidity. Economically, obesity accounted for 2.2% of global GDP in 2019 and is projected to exceed 3% by 2060. Emerging therapies, particularly glucagon-like peptide-1 (GLP-1) and dual GLP-1/glucose-dependent insulinotropic peptide receptor agonists, now achieve weight loss comparable to metabolic bariatric surgery while reducing cardiovascular, metabolic and hepatic complications, independent of weight loss. Future strategies must integrate precision medicine with equitable, scalable public health policies to address this escalating global epidemic and its societal costs.