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

ABSTRACT

BACKGROUND: Obesity 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. METHODS: A 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. RESULTS: A 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. CONCLUSIONS: Preoperative 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.