Test Your Knowledge

Unexplained weight changes are fluctuations in body weight that cannot be attributed to a recognizable cause, such as dieting or overeating. In other cases, a patient's weight change can be explained, but nonetheless is unintentional and may be undesirable.

Unexplained and unintentional weight changes include:

• Weight loss. Weight loss usually occurs when individuals "burn" or expend more calories than they consume. Common causes of weight loss include increased physical activity, dietary changes, mood changes, certain medications and temporary illness (e.g., gastroenteritis).
  
  
• Weight gain. Weight gain usually occurs when individuals consume more calories than they expend. Common causes of weight gain include lack of exercise, overeating, hormonal changes and certain medications.

When significant weight loss or gain cannot be explained by lifestyle factors (e.g., changes in diet or exercise) or temporary illness, it may be a sign of a more serious underlying condition. Numerous conditions can cause weight to fluctuate, such as eating disorders, endocrine disorders (e.g., diabetes, thyroid disease), heart disease, depression or cancer.

Sometimes a condition can involve either an increase or a decrease in weight, depending on the individual. For example, depression causes many people to eat less and lose weight, whereas others eat more and gain weight.