According to the study by Singhal V et al., one year after sleeve gastrectomy, fasting serum ghrelin levels in patients with obesity remained significantly lower, with a concentration of 36.0 ± 8.3 pg/ml, compared to 247.0 ± 35.5 pg/ml in the non-surgical control group (p < 0.0001) [43].A prospective cohort study conducted by Ozmen et al. demonstrated that patients with obesity who underwent sleeve gastrectomy achieved significant weight loss one year after surgery. Here, GHRL is linked to Obesity.