Not everyone who has a BMI in the range labeled "healthy weight" is at his or her most healthy weight. Some may have lots of fat and little muscle. A BMI above the appropriate weight range is less healthy for many people, but may be fine if you have lots of muscle and little fat. A BMI below the appropriate weight range may still be ok or it could mean that you are not getting the nutrients your body needs to develop and function at its best. Your BMI may change over time (depending on where you are in your development), so you may want to track it over a period of months. Your doctor can help you determine the healthiest weight and BMI for you.