Im sure you know this, but there are lots of things that your friend could do for
cardio that are low impact. Swimming, ellipticals, biking, even rollerblading are possible alternatives. If she really wants to run she's just going to have to start off slow and build up, so she can find her limits.
good luck at the luau! Just remember that no food tastes as good as being skinny feels. I always think that when Im tempted.
