Try looking at the symptoms for AMYLOIDOSIS. My mother also experienced loss of appetite, overall lethargy, heart, nervous system, liver and kidney decline. It is a very rare disease and very difficult to diagnose. Loss of appetite stemmed from her illness; it didn't cause it. Eventually she became so weak that her body couldn't rally against her heart attack. Other triggers may be Myeloma, Hepatitis C, renal (kidney) disease. I would recommend getting blood tests to check the presence of the amyloid protein and, also, creatinine level.