Although malnutrition is a common health and social care problem, there is no universal agreement about its definition, prevalence, or method of identification and report. Fifteen definitions of malnutrition were critically examined to assess their variability. They ranged from descriptions of undernutrition alone to under- and overnutrition, with intakes ranging from dietary protein and energy alone to dietary and nondietary sources of all nutrients and energy. Definitions also varied from non-outcome based to those based on functional, physiological, and/or clinical outcomes. Some definitions relied on the pathways by which malnutrition develops, with one apparently requiring loss of fat-free mass. Also examined were nutrition screening tools, diversely developed for detection of malnutrition, management of malnutrition, and prediction of clinical outcomes or health care usage. Their intended use also varied from specific care settings (hospital, community, care homes) to all settings and from specific age groups to all age groups. With all these definitions and tools, there is considerable scope for confusion and misunderstanding. Therefore, to clarify the burden and significance of malnutrition, guidelines for documenting it in routine practice and reporting it in scientific literature are provided.
Keywords: definition; identification; malnutrition; screening.