Your Healthy Weight: Body Mass Index
Once you know your BMI, you may want to check it every year or so to see where you fall compared to last year. This is one area of life where you really want to strive for the middle 85th percentile; being at the 95 percentile for BMI can be just as unhealthy as being at the 5 percentile for BMI.
Your BMI gives you a rough idea of where you stand weightwise, but it’s far from perfect. It tells you how you compare to everybody else your age and size, but it doesn’t account for things like whether you’re athletic or whether you have an unusually high or low BMR. Girls with more muscle may have a falsely high BMI number, since muscle weighs more than fat. In fact, when professional athletes measure their BMI, their results often suggest that they’re obese, which couldn’t be less true!
The healthy range is incredibly wide. My patient Anita (who’s seventeen, measures five feet four, and weighs 140) is in the healthy range—but that range goes from 101 to 146 pounds! So BMI is just one piece of the puzzle helping you figure out your best weight. Since Anita has a hormonal imbalance, I’d expect her to be on the high end of the normal range. But I also know she exercises nearly every day and has a very healthy diet. So landing somewhere in the middle makes sense for her. It’s also important to take into account elements like genetics and her metabolic rate.
When you factor in all these different variables, plus genetics and personal metabolic rate, it makes sense that there’s a wide range of healthy.