My understanding is that running creates stress in the form on Cortisol, which can actually inhibit losing fat. Weight lifting is much better than running, if you want to lose fat.
that and your muscle mass increases, even if you weigh the same fat % goes down.
17% isn’t really lean either, even for a woman. I am over 60 and 13%, when I was in college playing ball I was 6%, women are about 5% higher in the same level of conditioning.