Protein-energy malnutrition refers to a spectrum of presentations of poor nutrition caused by insufficient intake of protein and/or calories. Specific protein malnutrition with sufficient energy intake (sometimes referred to as kwashiorkor, although this term has a complex history: see definition) characteristically presents with oedema (swelling). Undernourishment but with sufficient protein intake presents with loss of muscle mass and subcutaneous fat (referred to as marasmus). The combination of these, marasmic kwashiorkor or simply severe PEM, shows both sets of symptoms. In practice, it is often impossible to make such neat distinctions. The fact that forms of PEM are typically accompanied by comorbidities complicates the picture further.