Metabolic and bariatric surgery (MBS) nowadays is seen as an effective means of treating obesity and related comorbidities. In the preoperative stage, candidates for MBS must receive a comprehensive assessment by a multidisciplinary team. This includes their medical history, anthropometric measurements, body composition, and biochemical monitoring while focusing on a nutritional status assessment as an essential component of this preoperative therapy. As part of this nutritional assessment, a registered dietitian (RD), during a clinical interview, should gather vital information from candidates for MBS about their previous attempts to manage their weight, eating habits, level of physical activity, and the expectations they have regarding MBS. The RD should also provide clear orientation about MBS, offering a personalized weight loss program that includes treatment of preexisting nutritional deficiencies, the need to lose weight before surgery, and incorporating physical activity into their routine, as well as the future adaptation of their eating patterns, lifestyle, and adherence to prescribed supplementation. With their conscientious follow-up of this orientation, candidates can look forward to progressive success in their goal of losing weight as they realize an improvement in both their general health and quality of life.