PDK4 and obesity due to melanocortin 4 receptor deficiency: Furthermore, increased acetyl CoA and nicotinamide adenine dinucleotide (NADH) production following high rates of fatty acid oxidation during obesity activates pyruvate dehydrogenase kinase 4 (PDK4), which inhibits PDH, the main enzyme of glucose oxidation, by phosphorylation [14, 36, 51].