Background: One anastomosis gastric bypass (OAGB) is safe and effective. Its strong malabsorptive component might cause severe protein–energy malnutrition (PEM), necessitating revisional surgery. We aimed to evaluate the safety and outcomes of OAGB revision for severe PEM. Methods: This was a single-center retrospective analysis of OAGB patients undergoing revision for severe PEM (2015–2021). Perioperative data and outcomes were retrieved. Results: Ten patients underwent revision for severe PEM. Our center’s incidence is 0.63% (9/1425 OAGB). All patients were symptomatic. Median (interquartile range) EWL and lowest albumin were 103.7% (range 57.6, 114) and 24 g/dL (range 19, 27), respectively, and 8/10 patients had significant micronutrient deficiencies. Before revision, nutritional optimization was undertaken. Median OAGB to revision interval was 18.4 months (range 15.7, 27.8). Median BPL length was 200 cm (range 177, 227). Reversal (n = 5), BPL shortening (n = 3), and conversion to Roux-en-Y gastric bypass (RYGB) (n = 2) were performed. One patient had anastomotic leak after BPL shortening. No death occurred. Median BMI and albumin increased from 22.4 kg/m² (range 20.6, 30.3) and 35.5 g/dL (range 29.2, 41), respectively, at revision to 27.5 (range 22.2, 32.4) kg/m² and 39.5 g/dL (range 37.2, 41.7), respectively, at follow-up (median 25.4 months, range 3.1, 45). Complete resolution occurs after conversion to RYGB or reversal to normal anatomy, but not after BPL shortening. Conclusions: Revisional surgery of OAGB for severe PEM is feasible and safe after nutritional optimization. Our results suggest that the type of revision may be an important factor for PEM resolution. Comparative studies are needed to define the role of each revisional option.

Bariatric surgeries may lead to an improvement in metabolic fatty liver disease, and a reduction in the levels of the hepatic enzyme Alanine Aminotransferase (ALT). We compared the effects of Sleeve Gastrectomy (SG), Roux en Y Gastric Bypass (RYGB) and One Anastomosis Gastric Bypass (OAGB) on the levels of ALT by analysis of two-year follow-up data from 4980 patients in the Israeli Bariatric Registry that included laboratory tests and demographic information. Pre-operative characteristics of patients, and particularly levels of liver enzymes, were similar across surgery types. Regression modeling and retrospective matching showed that SG was superior to RYGB and OAGB in reducing ALT levels, and in reducing the fraction of patients with abnormally high ALT levels. Two-year post-surgery, an increase in ALT levels from normal to abnormal levels was observed in 5% of SG patients, and in 18% and 23% of RYGB and OAGB patients. In conclusion, SG leads to a greater reduction in ALT levels compared with bypass surgeries and a lower incidence of post-surgical elevation of ALT levels. Further studies are required to identify the cause for the rise in liver enzymes, and to determine whether ALT levels correlate with liver pathology especially following bariatric surgery.