Malnutrition

Malnutrition is a state resulting from deficient, excessive, or imbalanced intake or utilization of energy or nutrients. In its broad public-health meaning, malnutrition includes undernutrition, micronutrient deficiencies or excesses, overweight, obesity, and diet-related noncommunicable diseases. Malnutrition therefore does not simply mean eating too little or being underweight .¹

Undernutrition is one form of malnutrition and occurs when the body receives or effectively uses insufficient energy or nutrients to meet its needs. It can result from inadequate food intake, impaired nutrient absorption, increased requirements, or illness-related metabolic changes. In clinical nutrition, the word malnutrition is often used more narrowly to refer to undernutrition, particularly in people affected by disease .²

Malnutrition cannot always be identified from body weight alone. An adult may experience clinically important weight loss or reduced muscle mass without having a low body mass index. The Global Leadership Initiative on Malnutrition (GLIM) therefore uses both phenotypic features and underlying causes in diagnosing adult malnutrition. Its framework requires at least one phenotypic criterion, unintentional weight loss, low body mass index, or reduced muscle mass, and at least one etiologic criterion, such as reduced food intake or assimilation or inflammation associated with disease .²

Malnutrition is also distinct from a nutrient deficiency. A deficiency refers specifically to inadequate status or availability of a particular nutrient, whereas malnutrition is the broader concept and can involve energy, multiple nutrients, altered body composition, or excessive energy or nutrient intake .^1,2