Systematic Dietary Interventions to Minimize Postoperative Weight Loss Following Orthognathic Surgery: a Randomized Controlled Trial.

OBJECTIVES: This randomized controlled trial aimed to assess whether structured dietary interventions, implemented both before and after orthognathic surgery, could minimize postoperative weight loss during the first eight weeks. MATERIAL AND METHODS: The study was conducted between April 2017 and April 2022, involving patients undergoing singleor bimaxillary surgery. Participants were randomly allocated into three groups: intervention 1 (nutritional tube feeding), intervention 2 (oral intake nutritional supplements), and control (standard care). Body composition was assessed using a body composition analyser (Tanita BC-418) at five time points: presurgery examination, admission, and follow-ups weeks 1, 3, and 8. Primary outcome was weight; secondary - BMI, fat mass, fat-free mass, total body water, and visceral fat rating. Compliance was assessed from patient questionnaires and hospitalization records based on adherence to the prescribed nutritional intake before and after surgery. RESULTS: In total 150 patients were included, without statistically significant differences in age (28.6 [SD 10.4] years, P = 0.7) and BMI (24.9 [SD 5.6], P = 0.72). All groups experienced significant weight loss postoperatively (week 1: P < 0.001; week 3: P < 0.001; week 8: P < 0.001), with control showing slightly greater loss at week 8 (-3.03 kg vs. -2.18 and -2.67 kg; P = 0.11). Compliance during hospitalization was higher in intervention 1 (71.8%) than intervention 2 (55.1%; P = 0.02). No significant differences were found in body mass index or body composition changes. CONCLUSIONS: There was no statistically significant effect of systematic dietary interventions versus standard care on postoperative weight loss or body composition after orthognathic surgery. Higher adherence did not improve clinical outcomes.