Child obesity has become a significant health issue in Korea. Prevalence of obesity in school-age children in Korea has been alarmingly rising since 2008. Prevalence of obesity among infants and preschool-age children in Korea has doubled since 2008. Obese children may develop serious health complications. Before nutritional counseling is pursued, several points should be initially considered. The points are modifiable risk factors, assessment for child obesity, and principles of treatment. Motivational interviewing and a multidisciplinary team approach are key principles to consider in managing child obesity effectively in the short-term as well as long-term. Nutritional counseling begins with maintaining a daily log of food and drink intake, which could possibly be causing obesity in a child. Several effective tools for nutritional counseling in practice are the Traffic Light Diet plan, MyPlate, Food Balance Wheel, and ‘Food Exchange Table’. Detailed nutritional counseling supported by a qualified dietitian is an art of medicine enabling insulin therapy and hypoglycemic agents to effectively manage diabetes mellitus in obese children.