An elderly relative of mine has suddenly lost his appetite. He is losing quite a bit of weight, and I am concerned. It would be very rare. There are other, more common, reasons why seniors stop eating. They include An undiscovered illness or infection can cause loss of appetite.
Some medications cause loss of appetite.
Others cause stomach upset or pain that discourages eating. Missing or decaying teeth make it difficult to eat. Poorly fitting dentures may cause pain so the person avoids eating. Alcohol is an appetite depressant. Lack of enthusiasm for grocery shopping and food preparation Poverty.