Why are both energy and protein checked when protein-energy malnutrition is suspected?
Energy and protein have related but different roles. Energy from carbohydrates and fats normally spares protein so that protein can build and repair tissues, make enzymes and hormones, and support immunity. When energy intake is inadequate, the body oxidises protein for fuel, leaving less available for growth and repair. Therefore, assessment of suspected protein-energy malnutrition must consider both total energy and protein intake, not protein alone.