Well...I don't like BMI because it doesn't consider muscle.
18-20 for men and women i think 25-27. that's around the military cut offs when it BMI.
it's such a useless measurement, and even more trivial is the mythical 25 or below figure. some skinny-fat can have a 24.9 BMI and be considered in great health, while a muscular guy of the same height is considered overweight.
xies would be perfect for the job.