Background. Roux-en-Y gastric bypass (RYGBP) is an established method for treatment of obesity, a condition of chronic inflammation with liver steatosis, characterised by increased erythrocyte sedimentation rate (ESR), white blood cell count (WBC), liver enzymes, and decreased magnesium (Mg). We investigated alterations, if any, in ESR, WBC, alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), and Mg after RYGBP. Methods. 21 morbidly obese nondiabetic patients who underwent RYGBP surgery were evaluated preoperatively (baseline), then 1 year (1st followup) and 3.5 years (2nd followup) after RYGBP and compared to an untreated control group. Results. Body mass index, ESR, WBC, ALT, and GGT were all significantly reduced at 1 year in the RYGBP group (30%, 35%, 20%, 45%, and 57%, resp.) while Mg increased by 6%, compared to control group (P = 0.001 − 0.009). Conclusions. Obese patients treated by RYGBP show sustained reductions in ESR, WBC, ALT, and GGT possibly due to reduced liver steatosis and increased Mg.