Losing weight without dieting or exercising sounds like a dream come true, but unexplained and excessive weight loss -- particularly if it is as high as 10 percent of your body weight in six months -- may indicate you suffer from an underlying medical problem. Excessive weight loss can be caused by a number of factors, including certain diseases, metabolic disorders, psychological problems and unusual lifestyle changes.
Metabolic disorders are caused by a disruption in the normal chemical metabolism process. This disruption can be the result of an organ failing to produce essential enzymes and compounds or an endocrine gland over or under-producing a hormone. Both hyperthyroidism and hypothyroidism -- an over or under-secretion of thyroid hormones -- cause weight loss, as well as diabetes, insufficient adrenal gland function and hypercalcemia, a condition in which the blood has abnormally high calcium levels because of excessive parathyroid hormone production.
Weight loss is a major symptom in a number of physiological diseases, including both benign and malignant cancers, tuberculosis, congestive heart failure, HIV infection, kidney disease, liver disease, chronic obstructive pulmonary disease, Crohn's disease and celiac disease. Crohn's disease, or inflammation of the intestinal tract lining, and celiac disease, an intolerance to wheat gluten, are only two of a wide variety of gastrointestinal conditions that disrupt digestion and can cause significant weight loss. Additionally, infection with parasites or certain types of fungi interferes with the body's ability to absorb the proper amount of nutrients.
Both mild and severe depression and mental disorders like schizophrenia or bipolar disorder may result in weight loss. Severe drops in weight can also signal undiagnosed eating disorder problems like anorexia or bulimia.
If you've been missing meals due to an usually hectic schedule, suffer from increased stress at work, school or in your personal life, have started taking a new medication or are recovering from a recent illness or infection, you may experience an unexpected drop in your weight. Age alone can impact your weight: the appetite of older adults often shrinks as their sense of smell and taste diminish with age.