In the discovery cohort, serum leptin was higher in NAFL (31.43 ± 3.59 ng/ml, p < 0.01) and NASH (37.62 ± 5.12 ng/ml, p < 0.001) vs. in non-obese controls (8.92 ± 2.88 ng/ml), showing a good performance when distinguishing non-obese controls from NAFLD patients, with AUROC = 0.88 (95% CI, 0.77–0.98; p < 0.0001) and an overall accuracy of 0.81 (95% CI, 0.68–0.91), considering 25% disease prevalence (Figure 1A). Here, LEP is linked to metabolic dysfunction-associated steatohepatitis.