Safety and Effectiveness of a 4-Week Diet on Low-Carb Ready-to-Eat Ketogenic Products as Preoperative Care Treatment in Patients Scheduled for Metabolic and Bariatric Surgery

Before metabolic and bariatric surgery (MBS), moderate weight loss and liver left lateral section (LLLS) volume reduction are desirable. Low-carb ketogenic diet-induced weight loss before MBS has been shown to have beneficial effects on the reduction in body weight (BW) and LLLS. However, the nutritional protocol of low-carb ketogenic diet may be hard to keep for prolonged periods due to the lack of sweet taste. Furthermore, transitioning to a low-carb ketogenic diet can cause people to crave foods that are restricted in the ketogenic diet, such as cookies, bread, pasta, and bagels. Therefore, many ready-to-eat low-carb ketogenic products (RLCKP) that mimic carbohydrate-rich foods despite a low-carb composition have been provided to make it easier for the patients to adopt a low-carb lifestyle. To date, there are no studies describing the dietary protocol for efficient and safe use of pre-operative RLCKP in terms of weight and LLLS volume reduction in patients with obesity scheduled for MBS. Therefore, the aim of this study was to assess the safety and effectiveness of a 4-week diet using RLCKP in reducing BW and LLLS volume in patients with obesity scheduled for MBS. Patients with obesity (<i>n</i> = 42) with a mean body mass index (BMI) of 42.4 ± 9.2 kg/m² scheduled for MBS underwent a 4-week preoperative RLCKP diet intervention. Their weight, LLLS volume, and biochemical and metabolic parameters were measured before and after the diet. Patient compliance was assessed by the presence of ketonuria and weight loss. Qualitative methods (5-point Likert questionnaire) were used to measure diet acceptability and side effects. All patients completed the study. We observed highly significant decreases in BW (-6.5%, <i>p</i> < 0.001), and LLLS volume (-22.3%, <i>p</i> < 0.001) and an amelioration of patient clinical status. All patients showed a high frequency of acceptability and compliance in following the diet. No adverse side effects were reported. Based on our findings, we were able to support the hypothesis that a 4-week preoperative RLCKP diet is safe and effective in reducing BW, and LLLS volume in patients with obesity scheduled for MBS.