Protein-calorie malnutrition refers to a condition that is caused by a deficiency of both protein and calories in one's diet. This is common in developing countries and is often seen in children who lack access to sufficient food sources. There are several synonyms for this condition, including protein-energy malnutrition, malnutrition, undernutrition, and calorie-protein malnutrition. These terms all refer to a serious lack of essential nutrients in the body, which can lead to severe health complications. To prevent protein-calorie malnutrition, it is crucial to ensure that individuals have access to a diverse range of foods that are high in protein and calories.