Unexplained Weight Loss

What is it?

Unintentional weight loss of more than 5% of body weight over 6–12 months is clinically significant and warrants thorough evaluation. In roughly one-third of cases, the cause is a malignancy. Other common causes include serious GI disease (malabsorption, IBD), endocrine disorders (hyperthyroidism, diabetes), psychiatric illness (depression, eating disorder), and chronic infections. In elderly patients, social isolation, dental problems, and polypharmacy are important contributors. A comprehensive workup including history, physical exam, labs, and imaging usually identifies the cause.

Common causes

When to see a doctor

• 1Any unintentional weight loss of 5% or more of body weight over 6 months
• 2Weight loss with fever, night sweats, or fatigue (possible malignancy or infection)
• 3Weight loss with diarrhea, abdominal pain, or blood in stool
• 4Weight loss with increased thirst, urination, or hunger (diabetes)
• 5Weight loss with racing heart, heat intolerance, or tremors (hyperthyroidism)
• 6Weight loss with low mood, loss of appetite, and sleep changes

What you can do

• ✓Track your weight weekly — consistent monitoring helps quantify the loss accurately
• ✓Eat calorie-dense foods: nuts, avocado, olive oil, cheese, protein shakes
• ✓Small frequent meals are more manageable if appetite is poor
• ✓Do not delay evaluation — unintentional weight loss has serious causes in 25–40% of cases
• ✓Address dental problems that make eating painful
• ✓Social meals and encouraging environments can improve intake in elderly patients

Conditions that cause this symptom

Medications that may help

Treatment depends on the underlying cause. Always consult your provider before starting any medication.

Frequently asked questions