I agree that your dad should probably see a doctor to be evaluated, but I have to tell you the exact same thing happened to my dad when he was about 85. He seemed to lose his sense of taste and then totally lost interest in eating. His doctor, who seems a little slow on the uptake
, finally put him on magase and now his appetite has somewhat returned, but he he is 6'1" and only weighs about 140. However, all his blood work and his heart are healthy! My doctor told me it's not unusual for the elderly to lose weight like that at some point, but it's important to know it's nothing that needs immediate attention. It very well may be nothing more than 'old age' but please insist he see his doctor for a checkup.