GATM and obesity due to melanocortin 4 receptor deficiency: Moreover, L-arginine:glycine amidinotransferase (AGAT) -deficient mice exhibiting creatine and hArg5 deficiencies were completely protected from diet-induced obesity and metabolic syndrome, whereas oral creatine supplementation resulted in a complete normalisation of the body weight and composition of these animals16, suggesting that the effect of AGAT deficiency on BMI is hArg-independent.