The Nature and Impact of Postoperative Dietary Counselling Delivered by Dietitians on Clinical Outcomes After Metabolic and Bariatric Surgery: A Systematic Review

Obesity prevalence has increased globally, and metabolic bariatric surgery (MBS) is the most effective treatment for severe obesity. However, the impact of postoperative dietary counselling (DC) on clinical outcomes including weight is unclear. This review aims to assess the nature and impact of postoperative DC delivered by dietitians on clinical outcomes in adults undergoing post-MBS, focusing on weight change as the primary outcome, and body composition, nutritional status, biochemical parameters, and complications as secondary outcomes. Five databases (Medline, Embase, Web of Science, CINAHL, and Cochrane Library) were searched for observational studies and randomised controlled trials (RCTs) assessing DC related to weight change. Thirteen studies met the inclusion criteria (five RCTs and eight observational studies), involving 4173 individuals. Eight studies reported no significant difference in weight outcomes between the groups receiving DC and comparison groups. However, secondary outcomes such as nutritional status, complications, and levels of transferrin saturation, vitamin B12, and vitamin D showed improvements with more frequent DC. The components of DC delivered by dietitians varied, including advice on micronutrient supplements, protein intake, physical activity, transition diets, healthy eating, and mindful eating. Evidence supporting the efficacy of postoperative DC in promoting weight loss is limited by short-term assessment and inconsistencies in reporting weight outcomes, highlighting the need for long-term RCTs to ascertain its effectiveness.