The usual effect of stroke to patients is loss of apetite. I am not aware of any researches that relates stroke to increased food intake. This could be a coping mechanism. However, as you mentioned, there should be a reduction of weight as part of the management of her condition. With hypertension, diet should be low on the salt and fatty portions. With heart conditions, diet should be low on the fatty or cholesterol portions. It would also be good to have her Ideal Body Mass Index computed to see how she fares on the scale.
Take care and keep us posted.