In the Korek et al. study, RBP4 levels did not correlate with BMI or fat mass and did not differ between individuals with obesity and those without obesity—RBP4 levels in both groups were 33.93 ± 4.46 and 32.53 ± 2.53 μg/mL, respectively [64]. This evidence concerns the gene RBP4 and obesity due to melanocortin 4 receptor deficiency.