Standard dietary regiments for bariatric are advised prior to surgery. The most used diet is a very low calorie diet (VLCD). These diets potentially have multiple pittfalls. Very low-calorie ketogenic diets (VLCKD) have been proposed as a new regimen for achieving weight- and liver volume loss in patients undergoing bariatric surgery. The beneficial effect of VLCKDs compared to (V)LCDs is the aimed preservation of FFM and RMR, while still reducing FM. Only a few small studies addressed the role of VLCKDs prior to bariatric surgery, and the data including FFM and FM is actually scarce. Therefore, a well-designed randomised controlled trial is necessary to establish the efficacy of a VLCKD.
According to the World Health Organization, obesity rates have nearly tripled since 1975, resulting in the mortality of four million individuals each year. Obesity contributes to a reduced quality of life and is a significant risk factor for multiple chronic diseases such as type 2 diabetes mellitus, cardiovascular disease, osteoarthritis and certain types of cancer . Bariatric surgery is regarded the most effective treatment for extreme obesity because it achieves significant long-term weight loss and improves or even eliminates obesity-related complications. Based on the American Society for Metabolic and Bariatric surgery, approximately 230.000 bariatric procedures are performed annually, and those procedures predominantly included sleeve gastrectomy and Roux-en-Y gastric bypass (RYGB) procedures. Bariatric surgery can be challenging because of an increased thickness of the abdominal wall, the presence of intra-abdominal obesity and hepatomegaly. These anatomical changes are associated with more anaesthetic and surgical manoeuvres during the procedure. Losing weight prior to the procedure is frequently advised because it may help to overcome technical challenges. It may furthermore improve short-term outcomes like surgical time, blood loss, hospital stay and postoperative complications, as well as long-term outcomes like weight loss. In the preoperative phase, weight loss can be realised by multiple dietary regimens, including low-calorie diets (LCD) (800-1500 kcal/day) and very low-calorie diets (VLCD) (\<800 kcal/day). In Máxima Medical Center and a few other hospitals performing bariatric surgery in the Netherlands, the VLCD is the standard diet of choice, which begins two weeks prior to surgery. Systematic reviews reported, as result of these diets, a reduction in liver size (5-20% with a VLCD; 12-27% with a LCD), intrahepatic fat (43% with a VLCD; 40-51% with a LCD) and body weight (2.8-14.8kg with a VLCD; 5.4-23.6kg with a LCD). These diets varied in duration, from two weeks to four months. One of the primary drawbacks of these diets is the loss of metabolically active fat free mass (FFM) and lean body mass (LBM), which are crucial for whole-body protein metabolism, in addition to fat mass (FM). In contrast to FFM, LBM contains bone mass, connective tissue, internal organs and essential fat stored in these tissues. It has been hypothesised that LBM will contain 3 to 5% more fat than FFM. A significant loss of FFM may negatively affect the resting metabolic rate (RMR), slow the rate of weight loss and predispose weight regain in the long-term. A significant loss of FFM, in continuing presence of an excessive FM, may furthermore contribute to sarcopenic obesity. A second important downfall is that some patients may not tolerate a (V)LCD regime due to side-effects leading to poor compliance and subsequently poor weight loss outcomes. For clinical trials, the reported attrition rate for a (V)LCD regime is around 20%, raising concerns about the study validity. Very low-calorie ketogenic diets (VLCKD) have been proposed as a new regimen for achieving weight- and liver volume loss in patients undergoing bariatric surgery. A VLCKD is characterized by a very low carbohydrate content (\<50 g/daily), a low-fat content (15-30 g fat/daily) and a high amount of proteins (1-1.5 g protein/kg ideal body weight). The beneficial effect of VLCKDs compared to (V)LCDs is the aimed preservation of FFM and RMR, while still reducing FM. In addition, the compliance of patients might be improved by VLCKDs, possibly due to the anorexigenic effect and hunger reduction of ketone bodies. Only a few small studies addressed the role of VLCKDs prior to bariatric surgery, and the data including FFM and FM is actually scarce. A retrospective cohort study found that a three-week lasting VLCKD resulted in more weight loss (5.8kg vs. 4.8kg) compared to a VLCD. In addition, two prospective cohort studies showed as result of a VLCKD, FFM was reduced by 7.6 kg (10.0%) and 0.7kg (1.1%) , whereas FM was reduced by 10.5kg (17.9%) and 5kg (8.8%). What is important to note is that these studies lack a control group, randomisation and are subjected to limitations in FFM and FM measurement due to the use of single-frequency bioelectrical impedance analysis (BIA). Therefore, a well-designed randomised controlled trial is necessary to establish the efficacy of a VLCKD.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
SUPPORTIVE_CARE
Masking
NONE
Enrollment
46
diets prior to bariatric surgery
diets prior to bariatric surgery
Maxima Medical Center
Veldhoven, North Brabant, Netherlands
RECRUITINGChange in FFM (%) in proportion to TBWL
The main outcomes are the change in FFM (percentage) in proportion to total body weight loss (TBWL) measured from baseline to two weeks after start of the diet.
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Change in weight
Weight (in kilograms), measured by Multi-frequency bioelectrical impedance analysis (MF-BIA), measured a total of three times. Twice before surgery: once prior to the diet and once after ending the diet. The last time 3 months after surgery
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Physical activity questionnaire
Measured by International Physical Activity Questionnaire (IPAQ). The IPAQ is used to estimate physical activity levels and to examine if there are differences in comparison to each diet and to assess differences preoperatively and postoperatively during and after completion of the diet. Measured in minutes per day. With a minimum of 0 minutes up to 1440 minutes a day. Higher scores might indicate higher levels of activity
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Patient satisfaction assessed by a questionnaire
5-point Likert scale: not at all satisfied, slightly satisfied, neutral, very satisfied and extremely satisfied). To assess the degree of contentment in regard to each diet. Higher scores results in more satisfaction
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Incidence of side effects, assesed by questionnaire
Measured by self-reported questionnaires, making use of a dichotomous scale (Yes; No). With a score Yes indicating the occurence of a side effect.
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Compliance assesed by return of diet sachets
Via the amount of sachets a patient has used. The patients has to bring the empty sachets along to their appointment. With the amount of sachets we will have insight to how many have been used and to the extent of compliance a patient has shown regarding their dietary intake. More sachets returned mean a possibly a higher compliance
Time frame: 2 weeks prior to surgery till the day of surgery
Change in weight
Weight (in kilograms), measured by and Dual energy x-ray absorptiometry (DXA), measured twice before surgery (prior to the diet and after ending the diet) and once three months after surgery.
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Upper extremity muscle strenght
Muscle strength (in kilogram), measured by handgrip peak strength, measured twice before surgery (prior to start diet and after finishing diet) and measured after surgery. Muscle strength is tested to map general upper extremity muscle strength.
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Surgical outcome (1)
Surgical time needed to perform the RYGB. Measured in minutes
Time frame: Day of surgery
Surgical outcome (2)
Hospital stay during admission. Measured in days.
Time frame: From day of surgery untill the day of discharge, counted as the nights a patient has stayed in the hospital for admission
Surgical outcome (3)
Complications occuring during admission up to 30 days postoperatively. Scored with a yes or no
Time frame: Day of surgery up to 30 days postoperatively
Surgical outcome (4)
Re-admissions occuring within 30 days postoperatively. Scored with yes or no
Time frame: Day of surgery up to 30 days postoperatively
Biochemical testing- Ketosis
B-hydroxybutyrate measurement in blood. Aim of this test is to measure the degree of ketosis. Elevated levels of B-hydroxybutyrate could indicate a state of ketosis
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Biochemical testing (Electrolytes- Sodium)
Sodium. Reference values between 135-145 mmol/L are seen as normal. Aim of the biochemical testing is to assess nutritional status
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Biochemical testing (Electrolytes - Potassium)
Potassium. Reference values of 3.5-5.0 mmol/L. Aim of the biochemical testing is to assess nutritional status
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Biochemical testing (Electrolytes - Albumin)
Albumin. Reference values of 31-44g/L. Aim of the biochemical testing is to assess nutritional status
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Biochemical testing (Liverfunction - Aspartate Aminotransferase (AST))
Aspartate Aminotransferase (AST). Reference values of \<31 U/L. Aim of the biochemical testing is to assess nutritional status
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Biochemical testing (Liverfunction - Alanine Transaminase (ALT))
Alanine Transaminase (ALT). Referene values of \<34 U/L. Aim of the biochemical testing is to assess nutritional status
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Biochemical testing (Liverfunction - Gamma glutamyl transpeptidase (GGT))
Gamma glutamyl transpeptidase (GGT). Reference values of \<38 U/L. Aim of the biochemical testing is to assess nutritional status
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Biochemical testing (Kidney function - Creatinine)
Creatinine. Reference values of 49-90 micromol/L. Aim of the biochemical testing is to assess nutritional status
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Biochemical testing (Kidney function - Urea)
Urea. Reference values of 2.5-6.4 mmol/L. Aim of the biochemical testing is to assess nutritional status
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Biochemical testing (Kidney Function - Estimated glomerular filtration rate (eGFR))
Estimated glomerular filtration rate (eGFR). Reference values of \>90 ml/min/1.73m2. Aim of the biochemical testing is to assess nutritional status
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Biochemical testing (Iron)
Iron. Reference values of 9-30 micromol/L. Aim of the biochemical testing is to assess nutritional status
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Biochemical testing (Hemoglobin)
Hemoglobin. Reference values ranging from 7.5-10 mmol/L. Aim of the biochemical testing is to assess nutritional status
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Biochemical testing (Metabolic profile - Total cholesterol)
Total cholesterol. Reference value \< 5mmol/L. Aim of the biochemical testing is to assess nutritional status
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Biochemical testing (Metabolic profile - low-density lipoprotein (LDL))
Low-density lipoprotein (LDL). Reference value \<2.6mmol/L. Aim of the biochemical testing is to assess nutritional status
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Biochemical testing (Metabolic profile - High-density lipoprotein (HDL))
High-density lipoprotein (HDL). Reference value \>1.1 mmol/L. Aim of the biochemical testing is to assess nutritional status
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Biochemical testing (Metabolic profile - Triglycerides)
Triglycerides. Reference value \<2.0 mmol/L. Aim of the biochemical testing is to assess nutritional status
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Biochemical testing (Calcium)
Calcium. Reference values ranging from 2.10-2.55 mmol/L. Aim of the biochemical testing is to assess nutritional status
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
Biochemical testing (Glucose)
Glucose. Reference values ranging from 4.0-7.8 mmol/L. Aim of the biochemical testing is to assess nutritional status
Time frame: 2 weeks prior to surgery, day of surgery and 3 months after surgery
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