Gastrectomy often results in significant metabolic complications due to the malabsorption of essential nutrients. This chapter will explore the metabolic disturbances following gastrectomy, focusing on deficiencies of iron, vitamins (B12, A, D, E), folic acid, and essential trace elements such as zinc, copper, and selenium. Post-gastrectomy patients frequently develop anemia, which can be attributed to deficiencies in iron, vitamin B12, and folic acid. Furthermore, deficiencies in vitamin B12, folic acid, and other nutrients can lead to severe neurological and psychological issues. Bone health is significantly impacted after gastrectomy due to malabsorption of calcium and vitamin D. Weight loss is a common consequence of gastrectomy, often due to a combination of reduced stomach capacity, changes in gastrointestinal hormones, and malabsorption of macronutrients and micronutrients. Post-gastrectomy metabolic complications can significantly impact patient quality of life and long-term health. Understanding the risks and implementing proactive measures for prevention, early detection, and treatment are vital to effectively manage these complications.