Metabolic/bariatric surgery (MBS) is a highly effective method for weight loss but can have a potential nutritional price to pay. All MBS teams must work towards minimizing its nutritional impact, which requires a holistic approach. This chapter explores the physiological aspects of nutrient absorption along with how various MBS procedures impact the absorption of different micro- and macronutrients. These procedures change the gastrointestinal anatomy and can lead to an increase in pre-existing nutritional deficiencies or cause new ones. To optimize the long-term results, a comprehensive understanding of the effects of these procedures on nutrient absorption is needed. Understanding the implications of MBS on nutrient absorption will lead to better preoperative education, better implementation of postoperative care, and early diagnosis and management of any nutritional deficiencies. It can also help healthcare practitioners guide their patients about what to expect, and when patients know this, it may lead to better adherence.