Preoperative dietitian-led Very Low Calorie Diet (VLCD) Clinic for adults living with obesity undergoing gynaecology, laparoscopic cholecystectomy, and hernia repair procedures: a pilot parallel Randomised Controlled Trial.

Obesity can increase risk of postoperative complications. Despite increased demand for patients living with obesity to lose weight prior to common surgical procedures, the impact of intentional weightloss on surgical outcomes is largely unknown. We aimed to conduct a pilot study to assess the feasibility of a full-scale randomised controlled trial to examine the effect of preoperative dietitian-led Very Low Calorie Diet (VLCD) Clinic on surgical outcomes in gynaecology and general surgeries.Between August 2021 and January 2023, a convenience sample of adults living with obesity (BMI≥30kg/m 2 ) awaiting gynaecology, laparoscopic cholecystectomy, and ventral hernia repair procedures were randomised to dietitian-led VLCD (800-1000kcal using meal replacements and allowed foods), or control (no dietary intervention), 2-12 weeks preoperatively. Primary outcome was feasibility (recruitment, adherence, safety, attendance, acceptability, and quality-of-life). Secondary outcomes were anthropometry and 30-day postoperative outcomes. Outcomes were analysed as intention-to-treat. 51 participants were recruited (n=23 VLCD, n=28 control), mean 48(SD13) years, 86%female, mean BMI 35.8(SD4.6) kg/m 2 . Recruitment was disrupted by COVID-19, but other thresholds for feasibility were met for VLCD group: high adherence without unfavourable body composition change, high acceptability, improved pre/post quality-of-life (22.1±15 points, <0.001), with greater reductions in weight (-5.5kg VLCD vs -0.9kg control, p <0.05) waist circumference (-6.6cm VLCD vs +0.6 control, p <0.05), and fewer 30-day complications (n=4/21) than controls (n=8/22) ( p >0.05). The RCT study design was deemed feasible in a public hospital setting. The dietitian-led VLCD resulted in significant weightloss and waist circumference reduction compared to a control group, without unfavourable body composition change, and improved quality-of-life.