Effects of short-term energy restriction prior to bariatric surgery on liver fat, inflammation and systemic metabolic parameters
Aims: To compare the effects of two very low energy dietary regimens on liver fat, inflammation and systemic metabolic parameters in severely obese adults prior to undergoing bariatric surgery. Methods: We conducted a prospective randomised clinical trial at the Royal Derby Hospital, May 2012 to June 2014, comparing outcomes of two energy restrictive regimens applied over 2 weeks: (1) food-based diet; (2) meal replacement plan (provided by LighterLife). Clinical and anthropometric information and fasting blood were collected pre- and post-diet, and a liver biopsy was obtained during surgery. Results: Of 60 participants recruited, 54 completed the study, food-based diet n=26, meal replacement plan n=28. Diet groups matched demographically: overall 81.5% female, median age 45 years, median body mass index (BMI) pre-diet 50.7kg/m2, 30% with Type 2 diabetes. Reported daily energy intake (median 715kcal/day) and body weight loss achieved (median 3.4%) were similar between groups. However, percentage of energy intake from carbohydrate, fat and protein were significantly different between groups. Circulating cholesterol, NEFA, CRP, fetuin-A and leptin all changed significantly in both diet groups; however, IL-6, triglycerides and glucose only changed significantly after the meal replacement plan. On liver biopsy, significant associations were found between diabetes status/impaired fasting glucose and histological grade of steatosis, lobular inflammation and non-alcoholic fatty liver disease (NAFLD) activity score. Conclusions: Both diet groups achieved significant weight loss prior to bariatric surgery; however, the meal replacement plan achieved greater modification in circulating biomarkers. Patients with Type 2 diabetes or impaired fasting glucose had greater severity of NAFLD on histology.