ABOS, Biological Atlas of Severe Obesity; ADA, American Diabetes Association; BA, bile acids; Bile acids; C4, 7alpha-hydroxy-4-cholesten-3-one; CA, cholic acid; CDCA, chenodeoxycholic acid; DCA, deoxycholic acid; Diabetes; FPG, fasting plasma glycaemia; FXR, farnesoid-X-receptor; GCA, glycocholic acid; GCDCA, glycochenodeoxycholic acid; GDCA, glycodeoxycholic acid; GHCA, glycohyocholic acid; GHDCA, glycohyodeoxycholic acid; GLCA, glycolithocholic acid; GUDCA, glycoursodeoxycholic acid; HCA, hyocholic acid; HDCA, hyodeoxycholic acid; HOMA2, homeostatic model assessment 2; HbA1c, glycated haemoglobin; IR, insulin resistance; Insulin resistance; LCA, lithocholic acid; MAFLD, metabolic associated fatty liver disease; NAFL, non-alcoholic fatty liver; NAFLD; NAFLD, non-alcoholic fatty liver disease; NASH; NASH, non-alcoholic steatohepatitis; OGTT, oral glucose tolerance test; Obesity; T2D, type 2 diabetes; TCA, taurocholic acid; TCDCA, taurochenodeoxycholic acid; TDCA, taurodeoxycholic acid; THCA, taurohyocholic acid; THDCA, taurohyodeoxycholic acid; TLCA, taurolithocholic acid; TUDCA, tauroursodeoxycholic acid; Translational study; UDCA, ursodeoxycholic acid