Intermittent Fasting Versus Carbohydrate Drinks Before Surgery

Preoperative Intermittent Fasting Versus Carbohydrate Loading to Reduce Insulin Resistance: a Randomised Controlled Trial

The purpose of this study is to investigate whether time-restricted feeding, a form of intermittent fasting, before surgery improves insulin resistance around the time of surgery, compared to carbohydrate drinks and standard fasting before surgery.

Patients in the Time-Restricted Feeding (TRF) group will follow a daily TRF regimen consisting of an 8h ad libitum eating period and a 16h water fasting period during the last two weeks before surgery, followed by routine preoperative fasting before surgery.

Patients in the CarboHydrate Loading (CHL) group will follow their usual diet in the pre-surgical weeks and will receive a maltodextrin beverage on the evening before surgery, as well as two hours before induction of anaesthesia.

Inclusion Criteria:

• Undergoing elective orthopaedic surgery;
• Intermediate, major or complex surgery according to the Surgical Outcome Risk Tool (SORT; http://www.sortsurgery.com/) severity of surgery classification;
• Scheduled for surgery at least 17 days from the date of screening;
• Motivated to follow a time restricted feeding regimen.
• Willing and able to provide written informed consent.

Exclusion Criteria:

• History of diabetes mellitus;
• History of feeding or eating disorders;
• History of delayed gastric emptying or gastro-oesophageal reflux
• Active malignancy
• Patients classified as ASA IV by the attending anaesthetist;
• BMI < 18.5 or ≥ 35;
• Outpatient or day case surgery;
• Palliative surgery;
• Participation in another clinical trial that is interfering with the procedures or outcomes of the PRINCESS trial;
• Patients unable to fully comply to study needs (e.g. legally incapable patients or patients unable to communicate in Dutch).