Variation and outcomes of liver-reducing dietary regimens before bariatric surgery: a national retrospective cohort study

Background Liver-reducing diets (LRDs) are mandated prior to bariatric surgery, but there are no guidelines on their implementation. Objective To establish the variation and effectiveness of LRDs utilized in clinical practice. Setting A nationwide, multicenter, retrospective cohort study. Methods A total of 1699 adult patients across 14 bariatric centers in the United Kingdom were included. Multilevel logistic regression models were developed to examine factors predictive of 5% weight loss. Results Most centers (n = 9) prescribed an 800- to 1000-kcal diet, but the duration and formulation of diet was variable. Overall, 30.6% (n = 510) of patients achieved 5% weight loss during the LRD. After adjustment for preoperative weight, women had reduced odds (odds ratio [OR], .65; 95% confidence interval [CI], .48–.88; P = .005), while increasing age (OR, 1.01; 95% CI, 1.00–1.02; P = .043) and having type 2 diabetes (OR, 1.49; 95% CI, 1.16–1.92; P = .002) increased odds of 5% weight loss. A normal consistency food LRD (OR, .64; 95% CI, .42–.98; P = .041) and energy prescription of >1200 kcals/d (OR, .33; 95% CI, .13–.83; P = .019) reduced odds, while an LRD with a duration of 3 weeks (OR, 2.28; 95% CI, 1.02–5.09; P = .044) or greater increased odds of 5% weight loss. Conclusions There is wide variation in how LRDs are delivered in clinical practice, highlighting the need for an evidence-based consensus. Our findings suggest the optimal LRD before bariatric surgery contains 800 to 1200 kcals/d over a duration of 3 to 4 weeks. Further research is required to determine the optimal formulation of LRD and whether women may require a lower-energy LRD than men.