Sarcopenia can be classified as age‐, activity‐, nutrition‐, and disease‐related. Hospital‐associated sarcopenia, acute sarcopenia, and iatrogenic sarcopenia are activity‐, nutrition‐, and disease‐related, not age‐related. There is considerable overlap between hospital‐associated sarcopenia and acute sarcopenia; however, they are distinct concepts. Some causes of hospital‐associated sarcopenia and acute sarcopenia are iatrogenic.