My Grace has lost some 25 lbs. in the last two years. She eats poorly most of the time. I try to give her small meals and fortified Ensure 2-3 times daily. Occasionally she'll eat ok but mostly moves food around in her plate. How does the caregiver deal with it?
Try for high value items that are easy to eat -- scrambled eggs, add some beans to your meals, etc. In Memory care facilities, they weigh each resident every month. Declines in weight are evaluated and supplements added.
Check out this comprehensive infographic, it contains other symptoms of Alzheimer's so you can have better understanding of the illness: http://www.infolongtermcare.org/iltc-news/infographic-all-about-alzheimers-disease/