Background: Few case reports have documented isolated metabolic disorders secondary to fat-soluble vitamin deficiency after malabsorptive operations for morbid obesity. The post-operative incidence of fat-soluble nutrient deficiency after surgery is unknown. We look at fat-soluble nutrient serum levels at one year and greater after biliopancreatic diversion (BPD). Methods: Patients undergoing malabsorptive operations for morbid obesity were evaluated at two medical centers. All patients were educated preoperatively regarding malabsorption and were prescribed mult-vitamins, fat-soluble vitamin supplements, iron and calcium post-operatively. In total, 164 patients underwent malabsorptive surgery for weight loss and were evaluated at 1 year (n=15) after surgery and greater than 2 years (n=149) for nutrients typically associated with fat malabsorption using blood sampling: Vitamin D, Vitamin A, parathyroid hormone (PTH), alkaline phosphatase (AP), corrected calcium and essential fatty acids. Results: Fifteen of 20 patients were available at 1 year follow-up and 149 of 161 were available after 2 year follow-up after BPD. Mean age was 47.1 (range 19-68), mean body mass index (BMI) was 49.6 kg/m2 (range 32- 86) and 79.2% were female. Mean drop in BMI was from 51.9 kg/m2 to 32.3 kg/m2 at 1 year and from 47.5 kg/m2 to 30.5 kg/m2 at 2 years. Mean % excess weight loss (%EWL) was 70.2% at 1 year and 64% at 2 years. Incidence of calcium deficiency was 18% at 1 year and 25.5% after 2 years, Vitamin D deficiency was 56% at 1 year and 36.2% after 2 years, Vitamin A deficiency was 33% at 1 year and 55% after 2 years, elevated PTH was 40% at year and 43.6% after 2 years, elevated AP was 19% at 1 year and 47.7% after 2 years. Essential fatty acid deficiency was seen in 100% of patients after 1 year. Conclusion: There is a high incidence of abnormal serum levels of nutrients known to be associated with severe fat malabsorption. Metabolic and functional sequelae are unknown. Frequent, long-term follow-up to allow close manipulation of these nutrients, is essential in patients who have undergone malabsorptive operations for weight loss.