Very low calorie diet in cardiac surgery patients with obesity and metabolic syndrome: short and mid-term outcomes

We aim to investigate the feasibility and outcomes of a preoperative supervised very low calorie diet (VLCD) program in elective cardiac surgery patients with obesity and the metabolic syndrome. All elective cardiac surgery patients who are obese (WHO BMI criteria / waist circumference) and have the metabolic syndrome (modified NCEP-ATP III criteria of hypertension, high cholesterol and treated diabetes mellitus) will be invited to participate in a supervised very low calorie diet program for six weeks preoperatively. The initial two weeks will utilise a VLCD only (3 liquid meal replacements / day, approx 800 calories / day). Whole foods will then be added over the subsequent four weeks using the Healthy Eating Plan devised by the Nutrition and Dietetics Department. The participants will be reviewed by a Dietician and Endocrinologist (diabetic patients only) upon recruitment to provide information regarding the VLCD program. They will be reviewed again by the Dietician at two weeks for reintroduction of whole foods. Diabetic patients will be monitored by the Endocrinologist weekly if their blood sugars are erratic or if they require changes to medications. Blood tests will be performed both on recruitment and preoperatively (approximately six weeks after VLCD use). No specific strategies will be employed to improve compliance. Encouragement will be provided during follow-up phone calls. Perioperative management will be conducted in a routine manner. We will analyse short and mid-term outcomes including weight loss, postoperative mortality, morbidity and length of stay. Patients will be contacted either by phone or mail, at 6 and 12 months post-operatively to complete a follow-up questionnaire. These results will be compared with retrospective data for: elective cardiac surgery patients (all-comers), elective obese cardiac surgery patients without metabolic syndrome, and elective obese cardiac surgery patients with metabolic syndrome who did not undergo the VLCD intervention.