BACKGROUND: A subgroup of obese patients without metabolic disorders has been identified and defined as metabolically healthy but morbidly obese (MHMO). OBJECTIVES: To compare Roux-en-Y gastric bypass (RYGB) outcomes between MHMO and metabolically unhealthy morbidly obese (MUMO) patients to assess whether the obesity phenotype could affect the results. SETTING: A university-affiliated tertiary care center. METHODS: One hundred nineteen consecutive patients underwent RYGB; 102 completed the 2-year follow-up and were divided into 2 groups (MHMO and MUMO) according to Wildman criteria, including blood pressure, triglycerides, high-density lipoprotein cholesterol (HDL-C), fasting blood sugar, C-reactive protein (CRP), and homeostasis model assessment of insulin resistance (HOMA-IR). Weight loss and metabolic parameter changes were analyzed. RESULTS: Twenty-one of 102 (20.6%) patients were identified as MHMO; they were mostly women (90.5%) and were significantly younger than MUMO patients (39.4 +/- 9.1 yr versus 47.2 +/- 10, P = .001); 12.6% were lost to follow-up. MHMO phenotype was significantly associated with a greater percentage of excess body mass index loss (P = .03), independent of gender, age, and redo procedures. All metabolic parameters were significantly improved 2 years after surgery in the MUMO group. HOMA-IR, CRP, and triglycerides were significantly lower 2 years after surgery in the MHMO group, whereas fasting blood sugar and HDL-C were unchanged. At 2 years of follow-up, 92.3% of the population was metabolically healthy. CONCLUSIONS: RYGB is an effective procedure to achieve weight loss and had a strong positive metabolic effect in both MHMO and MUMO phenotypes. RYGB led to an increase of the metabolically healthy status and may prevent or delay the onset of metabolic disorders.