A healthy diet that limits fat to 30% of calories, three meals per day and a variety of foods using the Food Guide Pyramid would be the best. There is no bad food, but eating too much food can cause weight gain, especially if physical activity levels drop. Foods high in fat and sugar usually don’t contribute as many vitamins and minerals and are very calorie dense. That is lots of calories per ounce of food. Limit high fat and high sugar foods to 1 or 2 servings per week if at all. Better to eat nutrient-rich foods. That is lots of vitamins and minerals with lower calories per ounce of food.
To get a goal weight, first, calculate her healthy body weight. For women start at a height of 5 feet and 100 pounds. Add 5 pounds for every inch of height over 5 feet. Height can be measured lying down and persons are usually taller when measured this way. For instance, a 5’4″ woman’s healthy body weight is 120 pounds plus or minus 10%. The healthy body weight range for this woman is 108 to 132 pounds.
Next, calculate calorie requirements based on 15 calories per pound. A woman weighing 120 pounds needs about 1800 calories per day. This would include basal calories and calories burned during very light activities. Using nutrition analysis software, I calculated her basal calorie requirements at 1337 calories per day, which doesn’t include activities. Basal calories are those needed just to keep the body systems running without any activity. Your friend, if a healthy body weight, should not go below this level.
You can also use my Healthy Body Calculator® to determine a personalized healthy body weight range and Calorie Goal. My suggestion would be to aim to maintain her weight while doing even passive exercises with a physical therapist
As physical activity decreases, so does lean muscle tissue (muscles and organs) which in turn decreases metabolic rate (basal calories). Your friend should weigh herself once a week to get a handle on how her plan to manage calorie intake and energy output.