Is anything wrong if I have lost weight inexplicably?

Unexplained weight loss may be a sign of many diseases, such as small intestine cancer, or none at all. You may have recently changed your diet or your exercise routine without being fully aware of it, or your body chemistry may simply be changing as you age. If the weight loss is very great, you are under the proper weight for your height, you also feel abdominal pain, or you feel tired all the time, consult your doctor. Only your doctor can make a diagnosis and determine a course of treatment.