I stressed about just this for ages when I was on SS, because the ideal weight for someone of my height was something obscene like half of my starting weight. I knew I was never going to reach that, and to try would have been crazy. I had problems with my original GP and have since moved, and now have a Doc that talks a lot of sense, and since speaking to her I now could not give a damn what my BMI is. I keep an eye on my Body Fat %age.
My doc says that BF% is a more accurate measure of your "healthy weight" that BMI can ever be. She says that a scale that operates on a "one size fits all" basis is going to be wrong in a large majority of cases.
She says if you can get your Body Fat %age into the acceptable range (25-31% for Women, and 18-25% for Men), and aim for what she refers to as the "Fitness Range" (21-24% for Women, and 14-17% for Men), then you have a healthy body. How healthy depends on how far you want to go.
I currently have a BF% of 19.5%, which is "Acceptable" ... to her. But not to me.
I am using diet and exercise to slowly bring my weight down and my fitness up. I am concentrating on "fat-burning" exercise rather than muscle building .......
BMI, says my Doc, is not worth worrying about. It is a very rough guide at best.
Steve