Recently, the terms frailty and sarcopenia have been used frequently. Frailty, which occurs due to age-related physiological changes in multiple systems, is accepted as one of the geriatric syndromes. In frailty, negative energy balance, decreased strength, slowed walking speed, decreased grip strength, sarcopenia and involuntary weight loss can be seen. Frailty emerges as an indicator of biological age and correlates with the outcomes of biological age regardless of age, gender and comorbidities. Recent studies have begun to use the concept of frailty in children. Frailty in children is caused by a multi-system physiological impairment, including neurological, endocrine, immune and skeletal systems, which leads to a deterioration in quality of life. Frail children therefore require additional care and related services compared to children of the same age. Sarcopenia is defined as progressive loss in the musculoskeletal system. It has been determined that frailty and sarcopenia have many things in common in terms of their formation mechanisms, clinical consequences, treatment and prevention methods. Nutrition is closely related to both frailty and sarcopenia. Therefore, adequate energy and protein intake is extremely important in preventing malnutrition and loss of lean body mass.