Unfortunatly, loose skin can only be reduced by building muscle from underneath or having it removed. I've trained hundreds of women that had the same goal. I was able to noticably tighten the skin in those areas through resistant training, but results were dependent on each individuals amount of excess skin. But all saw some improvement. To address your ab question, I know by witness that if the excess abdominal skin is removed, ur abs will be visable if the fat is gone and the muscles are developed.