There is a high prevalence of iron deficiency in patients who undergo bariatric surgery and effective therapies are lacking. Thus, there is a critical need for an effective, non-invasive, and inexpensive form of iron supplementation to treat iron deficiency and improve tolerance, the associated cognitive symptoms, and quality of life in the bariatric surgery patient population. Often, patients do not participate in bariatric programs, are not compliant, and/or are lost to follow-up. If there is a more effective and evidence-based guideline for repletion of iron deficiency, patients are more likely to be compliant. Therefore, in a randomized controlled study, the investigators propose to test the effectiveness of various iron formulations versus ferrous sulfate, which is the standard of care, for oral iron supplementation of iron deficient patients who have had RYGB or SG bariatric surgery. By randomizing patients into the two groups, the investigators will be able to determine the most effective regimen to improve blood biomarkers of iron status, cognitive function, and quality of life. Other outcomes will include adverse effects and compliance to the supplementation. The investigators will also analyze three-day food records to determine the contribution of dietary factors to changes in iron status. To test for improvement of iron status, serial blood draws will be performed during a time period of ~10 weeks. Serial blood draws from iron deficient patients have routinely been performed in past studies and have not been found to be harmful. Because this is a relatively short study (10 weeks), subjects will be able to recover quickly from the blood loss during the study. The investigators expect to find that iron supplementation with organic formulations of iron will be as effective than ferrous sulfate for repletion of iron deficiency, and they will be better tolerated. This project will address a significant health issue in individuals who have had bariatric surgery, which is a growing population in the United States. It is estimated that almost 1.5 million individuals have undergone bariatric surgery since the year 1990.