As BMI and mortality act in a “J-shaped” dependence and, because overweight and moderate obesity appear to be protective factors in critically ill patients, called the “obesity paradox” [36,52,53], we correlated serum PLIN2 with BMI and analyzed PLIN2 in different BMI subgroups (underweight vs. normal vs. overweight vs. obese; data not shown). This evidence concerns the gene PLIN2 and obesity due to melanocortin 4 receptor deficiency.