Obesity is a major public health problem. The population is growing older, and the prevalence of obesity in the elderly is rising. In normal aging, changes in the body composition occur that result in a shift toward decreased muscle mass and increased fat mass. This age-related progressive loss of muscle mass and strength is called sarcopenia. Sarcopenic obesity, which describes the process of muscle loss combined with increased body fat as people age, is associated with loss of strength and function, reduced quality of life, and even mortality. The pathogenesis of sarcopenic obesity is complex and involves multiple interactions between lifestyle, endocrine, and immunological factors. Recent epidemiological studies suggest that sarcopenic obesity is related to accelerated functional decline and high risk of diseases and mortality and, therefore, the identification of affected older patients should be an essential goal of clinicians. This paper addresses the definition and epidemiology of sarcopenic obesity and its underlying pathophysiology. In addition, this article describes the clinical significance and management strategies of sarcopenic obesity. (J Korean Diabetes 2013;14:166-173)