Unexplained weight loss of 10 pounds or up to 5 percent of normal body weight without any change in activity or food intake can be a sign of cancer, AIDS, pulmonary disease, drug abuse, stress or other chronic illness, according to MedlinePlus. Unexplained weight loss can take place over a period of six to 12 months and should be brought to a doctor's attention for prompt evaluation, according to MedlinePlus.
While unexplained weight loss can point to many serious diseases, it can also be an indication of an undiagnosed, yet treatable chronic condition such as depression, celiac disease, thyroid disorders, diabetes, ulcers or an eating disorder, according to the Mayo Clinic. When visiting a doctor for unexplained weight loss, the doctor will take a history to determine any other symptoms and conduct a physical examination, according to the Mayo Clinic.
Additional tests, including X-rays, blood work or a CT scan may be ordered to reach an accurate diagnosis, according to MedlinePlus. In the case that serious conditions and diseases are ruled out, a doctor may suggest dietary and exercise program changes or refer the patient to a nutritionist to help gain back the lost weight and maintain a healthy weight going forward, according to MedlinePlus.