Weight loss can be intentional, such as from dieting and exercise, or unintentional and be a manifestation of illness. Weight loss can result from a decrease in body fluid, muscle mass, or fat. A decrease in body fluid can come from medications, fluid loss, lack of fluid intake, or illnesses such as diabetes. A decrease in body fat can be intentionally caused by exercise and dieting, such as for overweight or obesity. Weight loss is normal after pregnancy. Other causes of weight loss include, but are not limited to, cancer, viral infection (such as CMV or HIV), gastroenteritis, parasite infection, depression, bowel diseases, and overactive thyroid (hyperthyroidism).
The loss of weight and lack of nutrition associated with a chronic illness is referred to as cachexia. Unexplained, unintentional weight loss is often a result of illness and should be evaluated by a health care professional.
REFERENCE:
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.
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Causes of Weight Loss
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Addison's Disease
Addison disease is a hormonal (endocrine) disorder involving destruction of the adrenal glands (small glands adjacent to the...
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Alcoholism
Alcoholism is a disease that includes alcohol craving and continued drinking despite repeated alcohol-related problems, such as...
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Amebiasis (Entamoeba histolytica Infection)
Amebiasis is an infection caused by an amoeba. Signs and symptoms include bloody stools, abdominal pain, weight loss, fever, and...
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Amyloidosis
Amyloidosis is a group of diseases resulting from abnormal deposition of certain proteins (amyloids) in various bodily areas. The...
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Anorexia
Anorexia is an eating disorder characterized by markedly reduced appetite or total aversion to food. Anorexia is a serious...
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Arthritis
Arthritis is inflammation of one or more joints. When joints are inflamed they can develop stiffness, warmth, swelling, redness...
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Bile Duct Cancer (Cholangiocarcinoma)
Bile duct cancer (cholangiocarcinoma) is a rare type of cancer that arises from cells that line the drainage system from the...
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Bone Cancer
Bone cancer is a rare type of cancer that occurs in cells that make up the bones. Primary bone cancer that arises in bone cells...
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Brucellosis
The bacteria Brucella causes brucellosis, an infectious zoonotic disease in humans. Symptoms and signs include fatigue, fever,...
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Bulimia
People with bulimia nervosa, an eating disorder that involves episodes of bingeing and purging, experience symptoms and signs...
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Cancer
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Cancer Risk Factors
Though it's difficult to say why some people develop cancer while others don't, research shows that certain risk factors increase...
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Colon Cancer
Colon cancer is a malignancy that arises from the inner lining of the colon. Most, if not all, of these cancers develop from...
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Connective Tissue Disease
Connective tissue disease is when the body's connective tissues come under attack, possibly becoming injured by inflammation....
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COPD (Chronic Obstructive Pulmonary Disease) Symptoms, Causes, Stages, Life Expectancy
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Crohn's Disease vs. Ulcerative Colitis (UC): Differences and Similarities
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Cryptosporidiosis
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Dehydration
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Dementia
Dementia is defined as a significant loss of intellectual abilities such as memory capacity, severe enough to interfere with...
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Depression
Depression is an illness that involves the body, mood, and thoughts and affects the way a person eats and sleeps, the way one...
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Diabetes (Type 1 and Type 2)
Diabetes is a chronic condition characterized by high levels of sugar (glucose) in the blood. The two types of diabetes are...
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Diabetes Insipidus
Diabetes insipidus is a condition in which the patient has frequent urination. Symptoms of diabetes insipidus include irritable,...
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Esophageal Cancer
Esophageal cancer is a disease in which malignant cells form in the esophagus. Risk factors of cancer of the esophagus include...
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Fitness
Regular physical activity can reduce the risk of disease. Regular exercise can also reduce the symptoms of stress and anxiety....
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Gastroesophageal Junction Adenocarcinoma
Gastroesophageal junction adenocarcinoma is cancer that forms in the area where the esophagus joins the stomach. Having GERD and...
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Giant Cell Arteritis (GCA or Temporal Arteritis)
Giant cell arteritis, inflammation of blood vessel walls, affects 10%-15% of polymyalgia rheumatica patients. Symptoms of giant...
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Graft Versus Host Disease (GVHD)
Graft versus host disease (GVHD) is a condition that happens when immune cells from transplanted donor tissue attack the...
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Hodgkin's Disease
Hodgkin's disease is a cancer of the lymphatic system with symptoms that include unexplained, recurring fevers, unexplained...
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Human Immunodeficiency Virus (HIV)
The human immunodeficiency virus (HIV) causes HIV infection and the acquired immunodeficiency syndrome (AIDS). Symptoms and signs...
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Hyperthyroidism
Hyperthyroidism is an excess of thyroid hormone resulting from an overactive thyroid gland. Symptoms can include increased...
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Irritable Bowel Syndrome (IBS) Symptoms, Diet, Treatment, and Test
Irritable bowel syndrome (IBS) is a GI (gastrointestinal) disorder with signs and symptoms of: Abdominal...
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Kidney Cancer
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Leishmaniasis
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Leukemia
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Lung Cancer
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Mantle Cell Lymphoma (MCL)
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Marburg Virus Disease
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Multiple Myeloma
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Non-Hodgkin's Lymphoma
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Pancreatic Cancer
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Pancreatic Neuroendocrine Tumors (Islet Cell Tumors)
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Parkinson's Disease (Symptoms, Signs, Causes, Stages, Treatment)
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Polymyalgia Rheumatica
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Relapsing Polychondritis
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Sarcoidosis
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Sleep Apnea
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Still's Disease
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Stomach Cancer
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Stretch Marks
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Thymoma
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Other Causes of Weight Loss
- Bowel Obstruction
- Dental Problems
- Infections (Parasites)
- Malabsorption
- Medications (Both Prescription and Nonprescription)
Examples of Medications for Weight Loss
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