UCP1 and obesity due to melanocortin 4 receptor deficiency: Concerning anti-obesogenic pollutants„ we discussed the effect of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), which have a reverse association with obesity and are associated with UCP1 upregulation and increased oxidative capacity in brown-fat mitochondria (Shabalina et al., 2015, 2016).