Figure 2a shows that PIC made no difference in nonesterified fatty acids in the blood, but it is possible that the fatty acids degraded in WAT were supplied to UCP1 in BAT, increasing energy expenditure. PGC-1α is a transcriptional coactivator that also regulates cellular energy production by promoting mitochondrial biogenesis and oxidative phosphorylation gene expression [52]. In humans, decreased PGC-1α expression is associated with obesity through reduced expression of oxidative phosphorylation genes and decreased muscle mitochondrial activity [53]. Here, UCP1 is linked to obesity due to melanocortin 4 receptor deficiency.