GPT and obesity due to melanocortin 4 receptor deficiency: Although elevated alanine transaminase has been proposed as a surrogate of NAFLD [36,37], in youths histologic studies and imaging procedures show that fatty liver is present in individuals with obesity whether the liver enzymes are elevated or not, suggesting that alanine transaminase elevation occurs at more advanced stages of NAFLD or in patients with extreme obesity [38,39,40].