Introduction Single-anastomosis duodenal switch has been suggested to be an effective bariatric procedure that offers excellent weight loss and by lengthening the common channel the potential to reduce micronutrient deficiencies. Purpose To evaluate the weight loss, comorbidity resolution and the 1-year nutritional outcomes of the single-anastomosis duodenal switch (SADS) procedure. Setting Multiple US Hospitals. Methods From October 2014 to January 2017, 120 patients were enrolled at six sites across the USA and underwent the SADS procedure. Weight loss, comorbidities, quality of life, and adverse events were followed post-procedure for 12 months. Results At 1, 6, and 12 months, 98.3%, 85.5%, and 77.1% of the patients were available for assessment, respectively. At 12 months, patients showed significantly reduced body mass index when compared to baseline (46.8 ± 5.8 vs 29.8 ± 4.4, P < 0.001 respectively). Sixty-five patients had type 2 diabetes at baseline; however, 11 patients lost to follow-up. Of the available data (54 patients), 96.3% of the patients had a resolution of type 2 diabetes by 12 months with a mean A1C reduction from 7.8 ± 1.6 to 5.3 ± 0.7. Additionally, there were reductions in hyperlipidemia, sleep apnea, and hypertension at 12 months. Patient gastroesophageal reflux disease satisfaction and quality of life (SF-36) scores were significantly higher at 12 months postprocedure (P < 0.001 in all cases) while 12-month protein levels remained at normal values. There were abnormalities of parathyroid hormone and vitamin D at 1 year with all other nutritional markers being not significantly different at 1 year from baseline. There were 10, IIIb, or greater complications according to the Clavien-Dindo scoring system during the study period, not all of which were related to the surgery. Conclusions SADS is a highly efficacious weight loss procedure with significant comorbidity reduction at 1 year. At 1 year, complications and vitamin and mineral deficits appear to be consistent with other malabsorption operations. Long-term follow-up is needed, especially around complications and vitamin deficiencies.