PPARGC1A and obesity due to melanocortin 4 receptor deficiency: To test our prediction that NT-PGC-1α−/− mice would be prone to HFD-induced obesity, male and female NT-PGC-1α+/+ (WT) and NT-PGC-1α−/− mice were fed a chow or high-fat diet (HFD) for 16 weeks starting at 5 weeks of age.