Obesity is a pandemic that affects nearly a third of the world's population, and its medical treatment has not achieved satisfactory or sustained results over time. Its counterpart, bariatric surgery (BS), has seen significant growth in recent years due to its favorable outcomes in weight loss and the resolution of comorbidities associated with obesity. Changes in diet, associated with the anatomical and physiological alterations resulting from BS, can lead to complications such as protein-calorie malnutrition and micronutrient deficiencies. Therefore, non-specialist physicians must be informed about these potential issues to ensure timely diagnosis and proper treatment. In this literature review, based on our center's years of experience as a national reference in bariatric surgery, we present the main nutritional complications associated with BS.