Weight loss, in the context of medicine, health, or
physical fitness, refers to a reduction of the total
body mass, due to a mean loss of fluid, body fat or
adipose tissue and/or lean mass, namely bone mineral deposits, muscle, tendon, and other connective tissue. Weight loss can either occur unintentionally due to malnourishment or an underlying disease or arise from a conscious effort to improve an actual or perceived
overweight or
obese state. "Unexplained" weight loss that is not caused by reduction in calorific intake or exercise is called
cachexia and may be a symptom of a serious
medical condition. Intentional weight loss is commonly referred to as
slimming.