Weight loss occurs when a person burns more calories, or energy, than he or she takes in. It may be deliberate or unintentional.
What is going on in the body?
A loss of weight is due to one of three factors:
fewer calories are consumed
more calories or energy are burned off during activity
a person's basic metabolism at rest speeds up
Weight loss may or may not be intended. Unplanned weight loss is often a sign of serious illness.
What are the causes and risks of the condition?
Some of the causes of weight loss are as follows:
cancer, including colon cancer, lung cancer, cancer of the pancreas, or leukemia
conditions that affect the ability of the intestines to absorb food and other nutrients
diabetes, a condition that results in high blood glucose levels
digestive diseases, such as inflammatory bowel disease or peptic ulcers
hormone imbalances, such as an increased thyroid hormone level known as hyperthyroidism
increased level of physical activity, due to exercise or manual labor
infections, such as HIV or tuberculosis
intake of fewer calories
medicine or drugs, such as amphetamines, ephedrine, cocaine, heroin, or alcohol
psychiatric conditions, such as depression, anorexia, or schizophrenia
severe kidney, liver, or heart disease
Other causes of weight loss are also possible. Sometimes a cause cannot be found.