There are many other causes of unexplained weight loss like worms in stool, depression, anorexia nervosa, AIDS, cancers especially colon cancers, drug abuse, infections and
loss of appetite.
Loss of appetite can again be due to certain medications, drug
abuse, depression, AIDS, acute and chronic infections, cancers and hypothyroidism. Either she does not eat well or there is increased metabolism as in hyperthyroid states, HIV, cancer etc.