BMI is a good measurement for populations (because populations regress to the mean), but not for people (because each of us is an “n of 1”). The real issue is insulin. If you look at the degree of insulin sensitivity at any given BMI, there’s a huge spread, meaning at any given weight, some will be healthy, and some won’t. What determines this isn’t the subcutaneous fat, but the liver (and secondarily, muscle) fat. You can’t determine these factors by looking at a patient’s BMI.
