Well, I've always read that all types of exercise are o.k., just don't go too far. We all know our limits.
I've fasted 30+ days and looked and felt wonderful. Flab was never an issue and when I dry brushed, loose skin wasn't either. Although, some be attribute that to genetics, but my mother had loose skin from up & down weight, so....
Problem areas are usually best worked with exercise. While fasting, you lose the weight where your body sees fit.