The 2021 Obesity Algorithm® is an essential tool for any practice; it contains updated information on the mechanisms, evaluation, and treatment of obesity, including why obesity is a disease, how obesity causes the most common metabolic diseases encountered in clinical practice, and how to treat obesity to reduce disease risk. This year’s update to the Obesity Algorithm includes an extensive template on how to start an obesity medicine practice and practical recommendations for treating patients with obesity via telehealth. Additional updates include information about obesity and organ transplantation, kidney stones, and orthopedic complications.