Bariatric surgery is an effective treatment for patients with morbid obesity. However, as safe and common as bariatric procedures have become, multiple complications can still result. These complications vary depending on the type of procedure performed (malabsorptive or restrictive) and are often nutritional derangements from the altered malabsorptive surface of the gastrointestinal tract and decreased capacity of the stomach. Deficiencies in vitamin D after malabsorptive procedures such as the Roux-en-Y gastric bypass can result in subsequent hypocalcemia and bone demineralization, and anemias can also present after surgery from inadequate vitamin B12 and iron absorption. Because of the prevalence of these deficiencies, baseline micronutrient testing and postoperative screening are recommended in many cases. Additionally, supplemental treatment often requires higher doses than those recommended for healthy adults. The purpose of this narrative review is to outline the various nutrient deficiencies that can result from bariatric procedures and report previously-published recommendations for screening and medical treatment of patients with these deficiencies. This review is directed toward primary care practitioners because of their unique position in delivering continuity of care and the frequency with which they will encounter patients who have undergone bariatric surgery and are seeking counseling regarding weight loss modalities.