According to the Korean obesity guideline, obesity is defined as who above 25 kg/m2 in body mass index. In Korea, obesity prevalence is 39.9% in 2019 over 65 years old. And it is expected more increasing due to aggressive moving to super-aged society. Obesity causes several comorbidities including diabetes, cardiovascular disease, stroke and cancer. Through these comorbidities, obesity is associated with increasing mortality. Obesity in elderly is distinguished by adult obesity throughout some characteristics. Among them, important characteristics are changes of body composition and redistribution of fat. Body composition and fat redistribution in elderly obesity break of balance between energy intake and expenditure. Especially, body composition changes with decreased muscle mass are accelerating obesity through lowering resting metabolic rate. Obesity elderly with decreased muscle mass have more incidence in disability and comorbidities. Hence, it is required to measure not only body mass index and body composition when diagnosing elderly obesity. In some studies, obesity elderly has more better health results including mortality than normal elderly. Considering this fact, it is important to approach careful when treat elderly obesity with weight loss. Before providing weight loss management, it is required to estimate the risk and benefit of weight loss treatment in the elderly patient. And for assist the estimation, detailed initial evaluation of obesity patient and body composition analysis is useful.