Protein–energy malnutrition (or protein–calorie malnutrition) refers to a form of malnutrition where there is inadequate protein intake.
- Kwashiorkor (protein malnutrition predominant)
- Marasmus (deficiency in calorie intake)
- Marasmic Kwashiorkor (marked protein deficiency and marked calorie insufficiency signs present, sometimes referred to as the most severe form of malnutrition)
Note that this may also be secondary to other conditions such as chronic renal disease or cancer cachexia in which protein energy wasting may occur.
Protein–energy malnutrition affects children the most because they have less protein intake. The few rare cases found in the developed world are almost entirely found in small children as a result of fad diets, or ignorance of the nutritional needs of children, particularly in cases of milk allergy.