Hello,
In my experience a liquid diet for that amount of time is usually an elemental diet, which uses specially formulated supplement drinks. These drinks contain all of the nutrients we need and are full of protein for healing as well as having a high calorie contents to meet the needs for each day and help patients gain weight.
In terms of a "normal" diet that's just liquid, soups are a good start, you will see conflicting advice on whether to stop dairy or not, but in my experience this very much depends on the person as while for some it appears to cause an increase in symptoms, for others its a very important source of nutrients. Perhaps it would be good to ask her doctors what they recommend in your sisters exact case. if she can tolerate milk then ice-cream, yogurts and milkshakes are also good, you can make a wide variety of milk shakes to suit her tastes. Milk is very good for calcium, protien and calories so I've always been advised to try and drink at least a glass a day even when on a full food diet (I do have problems with weight maintenance though and have the first stages of osteoporosis).
If you're going down the non dairy road, then use things like almond milk to make up smoothies with fruits of your choice (again, what she can tolerate will be different to what others can).
When I had a big operation on my jaw last year I drank gravy for the flavour when I got bored of soup, I also had something called complan (I don't know if you can get that outside of the UK ) which is a high nutrient drink that you can make with either milk or water to suit taste, these are good for calories and contain most basic nutrients, you will probably find something similar in your local pharmacies/drug stores.
Another thing my dietitians have recommended to me is to get pre-made drinks like mars shakes etc as these are really high in protein and calories (they do contain milk though), a favourite of mine is iced coffees (in moderation though because of the caffeine)
A good way to work out what specifically works for your sister would be to keep a food and symptom diary, include information on everything she eats/drinks and things like a pain score (1 is no pain, 10 is the worst pain imaginable) and whether she has any other symptoms like nausea. This will become especially useful when she eventually starts to re-introduce solid foods as it will make it easy to identify and eliminate any specific food thats causing an increase in symptoms.
I hope this helps a little, if you need any more specific advice or have another question please ask, someone will always try to help.
For some inspiration and information about things like juicing please check out our
diet forum
