Loss of appetite can again be due to certain medications, drug abuse
, depression, AIDS, acute and
chronic infections, cancers and
hypothyroidism. Either your mother does not eat well or there is increased metabolism as in hyperthyroid states, HIV, cancer etc. Poor absorption as in irritable bowel syndromes and malabsorption syndromes too is possible. Malabsorption syndromes are seen in intestinal tuberculosis, HIV, tropical sprue, parasites in stool and Whipple’s Disease.