BMI, in many cases, is considered a poor measure of health.
https://www.sciencefocus.com/comment/bmi-we-know-its-flawed-...
https://www.sciencefocus.com/comment/bmi-we-know-its-flawed-...
And the OP implicitly referenced these studies in his claim that being overweight could be healthier (which comes up in BMI studies of elderly people that don't sufficiently control for confounding factors)
Je n’ai fait celle-ci plus longue que parce que je n’ai pas eu le loisir de la faire plus courte.