Despite a greater risk of cancer associated with higher BMI, overweight (BMI 25–<30 kg/m2) and class I obese (BMI 30–<35 kg/m2) patients often have a paradoxically lower risk of overall mortality after a cancer diagnosis, a phenomenon called the “obesity paradox.” Only when patients exceed a BMI ≥35 kg/m2 are elevations in mortality risk consistently noted.