The prospective pilot study is designed to evaluate vitamin D status pre-operatively and post-operatively in 37 female patients undergoing either Roux-en Y gastric bypass or sleeve gastrectomy at The Methodist Hospital with 32 patients expecting to complete the 12 week trial. Women scheduled for either of these two types of bariatric surgery will be considered for inclusion in the pilot study. Based on previous research experience at The Methodist Hospital, the majority of bariatric patients are women. No children are treated at the Methodist Hospital bariatric center.