Weight loss refers to a decrease in body mass, typically measured in kilograms, resulting from a reduction in fat, muscle, or water content. Clinically, it is significant as it can indicate underlying health issues, such as malnutrition, chronic illness, or metabolic disorders, and is often a target in managing obesity and related conditions. One key association is unintentional weight loss, which may signal serious complications like cancer or hyperthyroidism, necessitating further investigation.