PPARGC1A and obesity due to melanocortin 4 receptor deficiency: In mice with diet-induced obesity, Gao et al. [35] found that butyrate improved insulin resistance by increasing mitochondrial biogenesis in brown adipose tissue by enhancing uncoupling protein (UCP)-1 and peroxisome proliferator–activated receptor (PPAR)-γ coactivator (PGC)-1α protein content, and enhancing type 1 fibres.