Effectiveness and Tolerability of a Two-Week Hypocaloric Protein-Rich Diet Prior to Obesity Surgery with Two Different Diet Interventions: a Prospective Randomized Trial

Purpose Preoperative very low-calorie diets (VLCDs) have been shown to reduce liver volume and improve bariatric surgery safety. Here, we compare two VLCD that differ in macronutrient composition. Material/Methods Ninety patients awaiting obesity surgery were included in a prospective, open-label, randomized mono-centre trial comparing the effects of 2-week preoperative VLCDs: BCM Diät™ (diet 1) versus Optifast™ (diet 2). Results Data from 33 patients in diet 1 and 36 in diet 2 could be analysed. There was no significant difference between the two diet intervention arms on outcome parameters. Overall, both VLCD strategies led to a mean weight reduction of 5.24 [4.72–5.76] kg ( p < 0.001), mean excess weight loss was 8.2 [7.4–9.1] % ( p < 0.001). BMI reduction was 1.81 [1.63–1.99] kg/m 2 ( p < 0.001). Over all patients, the liver volume was reduced by 397 [329–466] ml ( p < 0.001), which corresponds to 14.6 [12.4; 16.8] %. Liver fat content was significantly reduced by 18.35 [8.98–27.71] %. Reduction of body weight correlates with liver volume loss. In addition, hip/waist circumferences, body fat and fat-free mass decreased significantly. We found an increase of ALAT/ASAT and a significant decrease of triglycerides, LDL-cholesterol and HbA1c. Parameters of inflammatory were significantly reduced upon VLCD. Conclusion Independently of the macronutrient composition, VLCD leads to a significant decrease of body weight, reduction of liver volume and improved parameters of inflammation, glucose and lipid metabolism. Preoperative diets are widely used in conditioning; however, VLCD should be considered as option for patients with obesity undergoing other abdominal surgeries. Graphical abstract