f   I think it has more to do with the people in the 18.5-22 range than the skinnyfats. The former will include those with eating disorders, late stage cancer patients, and people who are genuinely underweight for their height and frame despite being "technically" healthy. Like the original obesity paradox study, if you exclude cancer patients, smokers, and those with eating disorders, normality resumes and those around a 20-23BMI win.