benefits could be satisfaction in one's self, rather than being insecure about one's body which can leads to social instability, emotional instability etc. another benefit is ability to be active. with a low body fat percentage everything in your body runs smoother and cleaner, therefore your body can do more for you when you ask it to be active. Health risks of high body fat percentage would be a higher risk of heart attack... that's everything off the top of my head as fast as I could.
