Body weight, as determined by several key components, remains relatively stable over time. Unintentional weight loss, defined as a decrease of more than 5% of usual body weight during a 6 to 12 month period, is an important predictor of morbidity and mortality. However, weight loss is a non-specific finding with multiple possible etiologies, that include organic, psychosocial, and idiopathic etiologies. A rational
stepwise approach based on relevant data extracted from the history and physical examination, with special attention to psychological and social issues, is highly effective in establishing a diagnosis and determining effective management. Treatment should be based on the results of the tests and each patient’s clinical situation.