OK - nice to see everyone has worked out the details on fat & muscle.
Figure out her BMI - don't use one of those online calculators. They don't figure in her level of activity. Use this formula:
Women: 655 + [4.36 x Weight (lbs.)] + [4.32 x Height (inches)] - (4.7 x Age) = your BMR
Next, to determine the amount of total calories your active body needs or its AMR simply multiply your BMR by the appropriate activity factor listed below.
Lightly active (normal, everyday activities)... BMR x 1.3 = Maintenance Calorie Level
Moderately active (exercise 3 to 4 times a week)... BMR x 1.4 = Maintenance Calorie Level
Very active (exercise more than 4 times a week)... BMR x 1.6 = Maintenance Calorie Level Extremely active (exercise 6 to 7 times a week for more than 1 hour duration)... BMR x 1.8 = Maintenance Calorie Level
By changing from a lightly active lifestyle to a very active lifestyle you can increase your caloric intake by 24% (about 500 calories).
Once you've completed the above calculations she should cut her AMR by 15% and consume this number of calories.