Low-calorie diets are effective for weight loss in patients undergoing benign upper gastrointestinal surgery: a systematic review and meta-analysis

Abstract

BackgroundObesity may increase surgical complexity in patients undergoing abdominal surgery by limiting visualization and increasing the risk of peri-operative complications. A preoperative reduction in weight and liver volume may improve surgical outcomes. The aim of our study was to evaluate the efficacy of a low-calorie diet (LCD) versus a very low-calorie diet (VLCD) in reducing weight and liver volume prior to laparoscopic surgery.MethodsA systematic search was conducted using the following inclusion criteria: obese patients undergoing preoperative weight loss using a VLCD or LCD, evaluation of liver volume reduction, and the use of an imaging modality before and after the diet.ResultsA total of 814 patients from 21 different studies were included in this systematic review and meta-analysis, with 544 female patients (66.8%) and a mean age range between 24 and 54 years old. There was a total mean weight loss of 6.42% and mean liver volume reduction of 16.7%. Meta-analysis demonstrated that a preoperative diet (LCD or VLCD) significantly reduced weight [SMD = − 0.68; 95% CI (− 0.93, − 0.42), I2 = 82%, p ≤ 0.01] and liver volume [SMD = − 2.03; 95% CI (− 4.00, − 0.06), I2 = 94%, p ≤ 0.01]. When assessed individually, a VLCD led to significant weight reduction [SMD = − 0.79; CI (− 1.24; − 0.34), p ≤ 0.01, I2 = 90%], as did an LCD [SMD = − 0.60; CI (− 0.90; − 0.29), p ≤ 0.01, I2 = 68%). Similarly, there was a significant reduction in liver volume following a VLCD [SMD = − 1.40; CI (− 2.77, − 0.03), p ≤ 0.01, I2 = 96%], and an LCD [SMD = − 2.66; CI (− 6.13, 0.81), p ≤ 0.01, I2 = 93%]. However, there was no significant difference between the two regimens.ConclusionsPreoperative restrictive calorie diets are effective in reducing weight and liver volume prior to laparoscopic surgery. Whilst a VLCD was better than an LCD at reducing both weight and liver volume, the difference was not significant.Graphical abstract