FOXO1 and obesity due to melanocortin 4 receptor deficiency: Additionally, obese aged mice exhibit increased levels of hepatic Foxo1; however, in postmenopausal women with overweight/obesity FOXO1 in PBMCs negatively correlates with MASLD indexes and DHA-rich n-3 PUFA supplementation upregulates FOXO1. Therefore, due to the dual role described for FOXO1 on MASLD development, future studies in large cohorts of well-diagnosed patients with MASLD/MASH are needed to establish if FOXO1 expression in PBMCs could be a biomarker of these pathologies and of the response to dietary/pharmacological lifestyle interventions.