There was a single study that showed that people who "overweight" but exercise have better health outcomes than people with normal BMIs who are sedentary. But that study included people who who are "overweight" by BMI standards but not excessively fat - like bodybuilders. They also included thin people with serious illnesses. They've latched onto that study to prove that one can be "fat and healthy." Which is just more evidence that fat makes you dumb.