It's well known that preventing excessive fat gain and being relatively lean is beneficial for your health. But there eventually is a point where "lean" becomes "too lean." To provide more clarity on this matter, a study was done to develop general guidelines on healthy body fat percentage ranges (See Study Here).
This study indicates that for males a body fat percentage of about 8-20% can be considered "healthy." For females, this was about 20-32%. (As the lower limit for competitive athletes).
With that said, it's worth mentioning that the tools commonly used in research (and real-life) to predict body fat levels can be quite inaccurate think BMI. So don't think its black-and-white when it comes to your body fat percentage.
These numbers are nothing more than general guidelines. It's not necessarily a bad thing if your prediction of your body fat percentage slightly deviates from this guideline.