ALDH7A1 and obesity due to melanocortin 4 receptor deficiency: [12, 39–41] Recent work showed that GPC, rather than a combination of GPE and GPC, was the main contributor to the changes observed in muscular PDE-levels in obesity and diabetes.[25] GPC has been shown to accumulate due to inhibition of oxidative phosphorylation, which strengthens the relationship with impaired oxidative capacity.