What is the best nutrition advice to feed my wife who weighs 80 pounds?

Protein shakes was recommended by my mother's nutritionist. My mother lost some weight on a pureed diet and lost about ten pounds, nutritionist recommended protein shakes Cabot Whey Powder, I mix it in her Cream of Wheat, add banana, milk and blend in the morning, and she loves it. She also recommended 70 gm of protein per day, I puree fish and salmon, mashed potatoes and a vegetable. I give my mom regular puddings with whip cream, little cheese cakes with pureed strawberries. I add the protein powder to her smoothies. She regained most of the weight she lost. Is it possible to consult with a nutritionist, via telephone or a telehealth call? I found the consult to be a tremendous help. Got lots of ideas, and recipes. Worth checking it out. You will need a doctors order so her insurance pays for the consult.

Take heart. I believe that the author Joan Didion has weighed 75 for more than a decade and is moving into her late 80s. She relates in a film her nephew did about her that the neighbors call him complaining about her weight all the time, and she has never weighed a whole lot more than she does now.
Ask your wife's doctor to order a nutrition consult, give him the weight and tell him of your worries. Then, with the doctors records, and knowing the patient, you can try to help this a bit. My partner has decades of GERD and honestly has come to dislike food in general. He is quite thing. I look at him and think "Well, 80 and pretty spry so you must be doing something right!"