Obesity is defined as an excessive amount of body fat or adiposity. It can be measured using the body mass index (BMI), and according to established criteria for adult men and women, overweight is defined as a BMI between 25–30 kg/m², and obesity as a BMI > 30 kg/m². Obesity is clinically associated with many serious co-morbidities, and is widely recognised as one of the leading health threats in most countries around the world. Weight loss is recommended for patients with a BMI > 25 kg/m². The goals of weight loss therapy are to reduce obesity-related co-morbidities and decrease the risk of future obesity-related medical complications. The management of obesity is multifactorial, and involves the use of combined lifestyle interventions, including regular physical activity and dietary and psychosocial intervention. Practical clinical advice regarding interventions in these important areas is provided in this article.