Unexpected Weight Loss

Medically Reviewed By William C. Lloyd III, MD, FACS

What is unexpected weight loss?

Weight loss as a symptom is any loss of weight that you cannot explain, or that you did not plan or work for through increased diet control and exercise. Unexpected, or unintended weight loss can be caused by diseases affecting almost any part of the body, including ongoing infections, AIDS, cancers, depression, painful mouth sores, missing teeth, chronic liver disease, kidney disease, respiratory disease, thyroid disease, heart disease, and chronic diarrhea or other digestive disorders. It can also be caused by loss of appetite due to dementia and by certain eating disorders such as anorexia nervosa or bulimia as well as malnutrition.

Some drugs are also known to cause abnormal weight loss. These include amphetamines, chemotherapeutic agents, and thyroid medications. Drug abuse involving excessive use of purgatives and laxatives, heavy street drug use, or smoking is also known to cause abnormal weight loss. Rapid or persistent weight loss is very dangerous and can cause severe damage to multiple organs and should always be investigated as soon as possible.

Seek immediate medical care (call 911) if you have heart arrhythmias; dizziness or wooziness; vomiting blood; dehydration; severe vomiting; severe diarrhea; severe abdominal pain; difficulty breathing; or confusion or loss of consciousness for even a brief moment.

If weight loss is persistent or otherwise causes you concern, seek prompt medical care.

What other symptoms might occur with unexpected weight loss?

If you experience weight loss without trying to lose weight, it may accompany other symptoms, which vary depending on the underlying disease, disorder or condition. Symptoms that frequently affect digestion may also involve other body systems.

Gastrointestinal symptoms that may occur along with weight loss

Weight loss may accompany symptoms affecting the digestive system including:

Psychological symptoms that may occur along with weight loss

Weight loss may accompany other symptoms affecting behaviors or thought processes including:

  • Alternating binging and purging
  • Depression
  • Difficulty with memory, thinking, or poor judgment
  • Distorted or inaccurate “overweight” body image
  • Excessive use of laxatives or diet pills
  • Intentional vomiting
  • Obsessive-compulsive behaviors
  • Refusing to eat in front of others or pretending to eat
  • Substance abuse

Other symptoms that may occur along with weight loss

Unexpected weight loss may accompany symptoms related to other body systems including:

Serious symptoms that might indicate a life-threatening condition

In some cases, weight loss may be a symptom of a life-threatening condition that should be immediately evaluated in an emergency setting. Seek immediate medical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms including:

What causes weight loss?

Weight loss as a symptom can be caused by diseases affecting almost any part of the body, including ongoing infections, AIDS, cancers, depression, painful mouth sores, missing teeth, chronic liver disease, kidney disease, respiratory disease, hypothyroidism, heart disease, and chronic diarrhea or other digestive disorders. Weight loss can also be caused by loss of appetite due to dementia or by certain eating disorders such as anorexia nervosa or bulimia.

Some drugs can cause abnormal weight loss as well. Rapid or persistent weight loss is very dangerous, can cause severe damage to multiple systems, and should always be investigated as soon as possible.

Gastrointestinal causes of weight loss

Weight loss may be caused by digestive or gastrointestinal system disorders including:

Endocrinologic causes of weight loss

Weight loss can also be caused by endocrine or hormonal disorders including:

  • Addison’s disease (disease characterized by underactive adrenal glands)

  • Diabetes

  • Hyperthyroidism (overactive thyroid)

Other causes of weight loss

Weight loss may also be caused by other conditions including:

Questions for diagnosing the cause of weight loss

To diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your weight loss including:

  • How much weight have you lost? Over what period of time?
  • Have you had any vomiting, diarrhea, or other digestive symptoms?
  • What other health problems do you have?
  • Have you been depressed or anxious about anything?
  • Do you have any other symptoms?
  • What medications are you taking?
  • Do you use any street drugs, drink alcohol, or smoke?

What are the potential complications of weight loss?

Because weight loss can be due to serious diseases, failure to seek treatment can result in serious complications and permanent damage. Once the underlying cause is diagnosed, it is important for you to follow the treatment plan that you and your health care professional design specifically for you to reduce the risk of potential complications including:

  • Amenorrhea
  • Bone loss or weakening
  • Cachexia or wasting syndrome
  • Organ failure
  • Spread of cancer
  • Spread of infection
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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Jan 8
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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