Unexpected weight changes

Last updated: January 25, 2022

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Weight changes can have primary causes (i.e., change of caloric intake or change of physical activity) and can be physiologic or pathological. Unexpected weight changes can have various secondary causes including weight loss due to malignancy or weight gain due to hypothyroidism and are always pathologic.

Unexpected weight loss is the unintentional or involuntary decrease in body weight (i.e., without the use of certain drugs including thyroxine and diuretics, a decrease of calory intake or an increase of physical activity) of > 5% of usual body weight over a time period of 6–12 consecutive months. It can be due to:


Unexpected weight gain is an unintended increase in body weight without an increase in calory intake or a decrease in physical activity. Common causes of unexpected weight gain include:


  1. Goldenberg K, Walker HK, Hall WD, Hurst JW. Weight Change. The history, physical, and laboratory examinations. 1990 .
  2. De Stefani F do C, Pietraroia PS, Fernandes-Silva MM, Faria-Neto J, Baena CP. Observational Evidence for Unintentional Weight Loss in All-Cause Mortality and Major Cardiovascular Events: A Systematic Review and Meta-Analysis. Scientific Reports. 2018; 8 (1). doi: 10.1038/s41598-018-33563-z . | Open in Read by QxMD

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