PDK4 and obesity due to melanocortin 4 receptor deficiency: The role of obesity and weight loss after bariatric Roux-en Y gastric bypass (RYGB) surgery was evaluated on peroxisome proliferator-activated receptor γ coactivator-1 α (PGC-1α) and pyruvate dehydrogenase kinase, where isoenzyme 4 (PDK4) is involved in mitochondrial function and fuel utilization in the skeletal muscle of obese women [75].