I don't think that BMI alone is an accurate measure of health. BMI is really nothing more than your weight.
BMI doesn't take body composition into account.
Body Mass Index is notoriously in accurate for athletes and for those who weight train. For these individuals it is quite easy for their weight to be skewed heavily into the overweight and obese categories. Arnold Schwarzenegger, one of the most lauded bodybuilders of all time......OBESE. You might argue that all you have to do is look at a person to know the difference between fauxbesity (don't you DARE steal my word!!) and real obesity, and that is true. But when things like insurance coverages are based blindly on that number, it is a real problem.
BMI doesn't take body frame into account.
Being big boned is not a myth and all bones don't weight the same regardless of what some snarky social media commenters like to say about it. There are measurable differences in body frame and this translates into measurable differences in weight.
"The standard is to use frame size in conjunction with height/weight charts and add roughly 10% for a large frame and subtract 10% for a small frame. For example, lets say that the ideal weight for a 5'10 man is 160. If a man has a small frame he may be overweight at 165 and should reduce by 10% to 150. In reverse a man with a large frame can be quite healthy at 180 lbs." source
BMI doesn't take sex or age into account.
There are evolutionary reasons that we gain weight after birth and with aging. I'll save those for another blog post.
BMI doesn't take race into account.
BMI doesn't take fabulosity into account.
As I walked the convention floor another lady, bespectacled and wearing a crisp white lab coat, walked up to me and asked, "Would you like your BMI checked?"
I turned to her and kindly replied, "I know what my height is and I know I weigh a hundred and ninety something pounds. I'm well aware that the BMI table says that's that I'm overweight or obese depending on the day of the month. So, no thank you."
Do you know what she said to me?
"Well I think you're beautiful either way."