What to do if my grandmother is 90 years old and weighs 93 pounds. what can she eat or drink to gain weight?

Whatever she wants!: At 90yo, your grandmother can typically afford to eat & drink whatever she wants, especially if she only weighs 93 pounds. We get concerned as to why she's only 93 pounds, such as depression, cancer, emphysema etc. Some medications can decrease appetite. Perhaps she has bad heart burn or difficulty chewing/swallowing food b/c poor dentition or stroke. Take her to see her Family Doc or Geriatrician