It has been observed by others that the upregulation of glucose-6-phosphate dehydrogenase (G6PD) in the liver of obese and diabetic animals can exacerbate oxidative stress and impair tissue function, suggesting that abnormal G6PD expression in obesity may contribute to metabolic dysfunction by disrupting energy balance and redox homeostasis [76]. Here, G6PD is linked to obesity due to melanocortin 4 receptor deficiency.