For her diet, introduce isolated soya protein. Also you can give her multi-vitamin tablet Centrium daily one.
In physical activities, try to organise and arrange games and other sports activities that she likes. You should also sit down with her an do some dream-building wherein it will help her to find out what is that she likes and live up to it. Besides all this, both parents should start their own fitness regime. Parents being fitness conscious themselves can motivate their children to be the same. Thus, the entire family cultivates a habit of team effort. This is known as Think fitness in Groups. Let her friends also be fitness freak.
However, with regards to diet, I would need certain details like her food habits, her food preferences, what are her tastes in food, her routine days food schedule, etc. Also, her medical and psychological history.