+1 to this. At BMI 35+ with a Co-Morbidity, or BMI 40+ they're considered "Morbidly Obese" which is medical  speak for Deathfat. Although Id venture to say BMI around 35 is still recoverable, when your fat mass gets much over 40 for any length of time you're doing serious and often permanent damage. Hence: Deathfat.