You're misrepresenting this study a bit. They are not claiming that being morbidly obese is healthy per se, just that BMI should not be the criteria for determining increased insurance premiums because there are exceptions (i.e extremely muscular people and statistical outliers) who unjustly suffer higher costs as a result.  But people like Bjornsson are a very small percentage of the population.  There are people who smoke and don't have lung cancer.  If you aren't a bodybuilder, high BMI is a massive health risk just like drugs and alcohol.  The 1959 MetLife tables don't lie. At the very least, if BMI is inaccurate, why not use body fat percentages and only apply the BMI surcharge if you don't have a low body fat percentage?