I'm not current for people of her age, but for the average 50 year old, you need to put down a minimum of 1500 calories a day to tread water weight and energy wise. Anything less and you are not going to get the proper nutrition, and you will lose weight. The average can of Ensure is between 200 and 250 calories. You need to be in the 6-8 cans a day level to just get by. Supplemented by my favorite...ice cold slippery peach slices out of the can in heavy syrup, you can get the total calories up there. They slip down the old throat without an issue, and cool the sores off on the way. Some combination of all this needs to get the total caloric intake up to the proper levels.