Malnutrition

Malnutrition is inadequate intake or absorption with measurable effects on body tissues, function, or recovery. It is not synonymous with being thin, underweight, or frail. A patient with obesity can lose substantial muscle and fat while remaining above a “normal” BMI. Conversely, a low body weight alone does not explain why weight is low or prove that malnutrition is present. The cause matters. Acute illness or injury can produce marked inflammation and rapid catabolism. Chronic disease may create sustained, milder inflammation and prolonged losses. Social or environmental malnutrition may result from inadequate food access or starvation without inflammation. These categories affect the diagnostic approach and how cautiously nutrition can be restarted. Risk rises with dysphagia, painful chewing, poor dentition, nausea, vomiting, diarrhea, chronic gastrointestinal disease, depression, social isolation, limited food access, prolonged NPO status, recent surgery, trauma, burns, cancer, chronic lung or cardiac disease, and any condition that increases metabolic demand. These are reasons to assess promptly, not diagnoses by themselves. The bedside question is not simply, “Does this patient look thin?” It is, “What has changed in intake, weight,...