Patients in the 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 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.
The purpose of this study is to investigate whether intermittent fasting before surgery improves insulin resistance around the time of surgery, compared to carbohydrate drinks and standard fasting before surgery.