Is Weight Loss Normal After Colonoscopy?

My best friend is a 55 year old female, married 36 monogamous years, no smoking, no drugs, no alcohol, no medications, no foreign travel in 6 years. She has lost 22 pounds in 3.5 months without trying. No other symptoms. She had unremarkable routine colonoscopy 11 months ago. In past 6 weeks, she has had negative endoscopy, negative abdominal and pelvic sonograms and CT-scans, and negative chest x-ray. Negative diabetes, negative thyroid problem, and all bloods done (including some cancer marker tests) have been normal, with the exception of high cholesterol/triglycerides. Her primary care is now sending her to hematologist to be thorough. Any suggestions? Her weight loss is sudden and scary.