"[BMI] was actually made to look at the health of larger populations. It was not designed for individuals to track their health," said Dr. Matt Tenneberg at Arcadia Health and Wellness Chiropractic, where he works with professional athletes. "The reason that it works so well for population studies is because it works most of the time, not all of the time. The errors in a larger population study will eventually regress back to the mean and the data will be relatively accurate. On an individual basis, you want the measurement to be as accurate as possible."
So how can I tell if I'm healthy?
Thanks to technology (sometimes it's good, technology), there are better ways to calculate your overall health -- though it's also smart to see a doctor.
Dr. Davidson says that more accurate measurements that calculate body fat (as opposed to weight), and whether or not you need to lose weight, including such Googlable wonders as underwater/hydrostatic weighing, bioelectrical impedance, DXA, MRIs, and the BODPOD. Still, each of these has its drawbacks, as some come with a hefty price tag and others only focus on fat.