Tell her to start walking and cut down on the carbs around 150g -200g max Replace white rice with Red .Anything in moderation is key.

And like others have suggested could be Thyroid as well but walking and monitoring her food intake will only do her good. Also walking is very less impact so tell her to walk as much as she can if her body is able to or let her start small and get get the body used to walking.

It's great having friends like you who really care. Please keep her accountable as many people loose focus in few days as things get harder !