Effects of a very low calorie diet in the preoperative stage of bariatric surgery: a randomized trial

Abstract

Background: Preoperative bariatric patients can follow very low calorie diets (VLCD), reducing surgical risks. However, possible advantages of a liquid diet over one of normal consistency are controversial. This study investigated the effect of a liquid VLCD compared with one of normal consistency considering visceral fat (VF) loss and metabolic profile in preoperative clinically severe obese patients.

Methods: This was a randomized, open-labeled, controlled clinical trial. Patients were divided into 2 groups: liquid diet and normal diet. Data were collected at baseline and 7 and 14 days after intervention. Information gathered was analyzed for loss of weight and VF, biochemical data, anthropometric data, and energy intake.

Results: Fifty-seven patients consumed the liquid diet and 47 consumed the normal consistency diet. The liquid diet group lost significantly more weight (P<.0290) and VF (P<.0410) than the normal diet group. An inverse correlation occurred between VF loss and surgical time among the liquid diet group (r2=-.1302, P=.001). Additionally, there was a positive correlation between the percentage of excess weight loss and ketonuria (P=.0070). No between-group difference occurred regarding calorie intake.

Conclusion: Patients that consumed a liquid diet presented a positive effect on reducing VF and greater weight loss than the normal diet group. Both VLCDs presented benefits offering a protective effect during the preoperative stage.

Keywords: Bariatric surgery; Liquid diet; Obesity; Very low calorie diet; Visceral fat.