If my bmi says im overweight but im fit and have a lot of muscle. am i unhealthy, do i need to lose weight?

No: BMI is just a rough measure. It is more important to be fit. Some experts suggest that the waist line size is a better indicator for assessment. Since muscle is heavier than fat, it is not surprising that you are considered overweight when measured by BMI.

Research tool: The BMI is based on several generalizations. These include that a person of a given age would have an "average" amount of muscle & bone & organs and all the rest would be fat. It is a better tool for looking at large populations than individuals. If your body fat content is down in the 10-12% range as many athletes are at your age the BMI is not going to be an accurate measure of your fitness.