The one-anastomosis gastric bypass (OAGB) is one of the most popular performed bariatric surgeries and has good long-term success for treating obesity and metabolic diseases. However, some patients can develop severe complications such as malnutrition and hepatic steatosis, which can be corrected with a reversal procedure, as seen in this case. A 20-year-old woman underwent OAGB surgery, which was converted to Roux-en-Y gastric bypass 4 months after the initial procedure due to malnutrition, both surgeries were performed at a hospital in southern Mexico. After the second surgery, she presented to our hospital with intolerance to oral feeding, vomiting and loss of 44 kg in 4 months. The patient was stabilized and scheduled for reversion surgery to normal anatomy 5 months later. She had good short-term nutritional outcomes and at the 1-year follow-up her total weight gain was 14 kg.