Obesity has reached epidemic proportions in Australia, with 67.5% of men, 52.1% of women and 19%-23% of children and adolescents being overweight or obese. Genetically predisposed individuals are especially vulnerable to developing obesity in the highly obesogenic environment of 21st century Australia. Obesity causes or contributes to many comorbidities, including type 2 diabetes, hypertension, dyslipidaemia, sleep apnoea, non-alcoholic steatohepatitis, orthopaedic problems and polycystic ovary syndrome. Management in the individual requires their complete co-operation and should be tailored to individual needs and complications. Management of obesity in children should consider the family context and involve the parents. All treatment strategies must involve lifestyle modification, with a reduction of energy intake and an increase in physical activity. Some patients may also require the assistance of drug therapy or bariatric surgery.