As the use of bariatric surgery for treatment of extreme obesity adults continues to rise, clinicians must be aware of pre-existing nutritional deficiencies in overweight and obese patients. Nutritional deficiencies are common in patients undergoing bariatric surgery and these deficiencies should be detected and addressed early to avoid post-operative complications. To improve long-term outcomes following bariatric surgery, nutritional screening and prescribing appropriate supplementation to prevent nutrient deficiencies is needed. Vitamin D deficiency is common following bariatric surgery and has been reported to occur in 50-80% bariatric patients.The goal of this pilot study is to help develop nutrient supplementation interventions following two types of bariatric surgery: Roux-en Y gastric bypass and sleeve gastrectomy.