Regarding the circulating markers of BAT activity, CXCL14, secretin, and 12,13-dihydroxy-9Z-octadecenoic acid (12,13 di-HOME) were similar in the two groups, whereas there was a trend for higher FGF21 in the subjects overweight/obesity. This evidence concerns the gene FGF21 and obesity due to melanocortin 4 receptor deficiency.