Unexplained Weight Loss: Causes & Testing

Unexplained weight loss is a concerning symptom that occurs without intentional efforts to lose weight, such as changes in diet, exercise, or lifestyle. It often signals an underlying medical condition, especially if the weight loss is significant or occurs rapidly. Here’s an overview of potential causes, when to see a doctor, and tests that may be recommended.

Potential Causes of Unexplained Weight Loss

1. Metabolic and Endocrine Disorders
   • Hyperthyroidism: An overactive thyroid increases metabolism.
   • Diabetes: High blood sugar levels can cause rapid weight loss.
   • Adrenal insufficiency (Addison’s disease): Reduces the body’s ability to handle stress and metabolism.
2. Gastrointestinal (GI) Issues
   • Celiac disease: Gluten intolerance affects nutrient absorption.
   • Crohn’s disease/Ulcerative colitis: Inflammation of the GI tract leads to poor absorption and weight loss.
   • Peptic ulcers: Reduced appetite due to pain.
3. Infections
   • Chronic infections: Such as tuberculosis (TB) or HIV/AIDS.
   • Parasitic infections: Like giardiasis or tapeworm infestations.
4. Cancer
   • Common types: Lung, pancreatic, stomach, or esophageal cancers can cause significant weight loss.
   • Mechanism: Often due to loss of appetite, increased metabolism, or nutrient-wasting tumors.
5. Mental Health Conditions
   • Depression: Can reduce appetite and lead to weight loss.
   • Anxiety: May cause nausea and reduced food intake.
   • Eating disorders: Such as anorexia or bulimia.
6. Neurological and Autoimmune Conditions
   • Parkinson’s disease: Increased energy expenditure or difficulty eating.
   • Lupus: Inflammation and associated symptoms may reduce appetite.
7. Chronic Diseases
   • Heart failure: Severe cases can lead to unintentional weight loss (cardiac cachexia).
   • Kidney or liver disease: Loss of appetite or metabolic changes.
8. Medications and Substance Use
   • Drugs: Certain medications, including chemotherapy or stimulants, can reduce appetite.
   • Substance abuse: Alcoholism or drug dependency.

When to See a Doctor

• Weight Loss Threshold: Losing more than 5% of your body weight within 6–12 months without trying.
• Accompanying symptoms: Fatigue, loss of appetite, persistent fever, pain, or changes in bowel habits.

Diagnostic Testing for Unexplained Weight Loss

1. Medical History and Physical Exam
   • Review symptoms, diet, lifestyle, medications, and medical history.
2. Basic Blood Tests
   • CBC (Complete Blood Count): Detects infections, anemia, or blood cancers.
   • CMP (Comprehensive Metabolic Panel): Assesses liver and kidney function, electrolyte levels.
   • Thyroid Function Tests: Diagnoses hyperthyroidism or hypothyroidism.
   • HbA1c or Glucose Tests: Screens for diabetes.
3. Imaging Studies
   • X-rays, CT scans, or MRIs: Detect tumors, organ damage, or infections.
4. GI Testing
   • Endoscopy/Colonoscopy: Checks for ulcers, celiac disease, or inflammatory bowel disease.
   • Stool Tests: Identifies infections or malabsorption issues.
5. Specialized Tests
   • Hormonal Panels: For adrenal or pituitary gland disorders.
   • Infectious Disease Screening: For TB, HIV, or other chronic infections.
   • Cancer Screenings: Based on symptoms and risk factors (e.g., mammogram, PSA test)