Efficacy of pre-operative'liver shrinking'dietary regimens: a UK national cohort study

Research output: Contribution to journalMeeting Abstract



Low energy diets (LEDs)(1000-1200kcal) and very low energy diets (VLEDs) (<800kcal) have been shown to significantly reduce liver size in preparation for laparoscopic bariatric surgery. However, pre-operative dietary practices vary considerably and research to date has not examined the efficacy of a range of pre-operative diets within clinical practice. Thus, our study aimed to establish the variation in, and efficacy of, pre-operative dietary regimes utilised in practice across the UK.


We conducted a retrospective cohort study of all patients who underwent a primary bariatric procedure at 16 participating UK bariatric centres between 1st January 2019 to 31st December 2019. Patient demographic data (gender, age, ethnicity), diabetes status and weight at baseline and on the day of surgery was collected. We also collected data about the pre-operative diet regimes, including kcals/day and duration. A multilevel linear random effects model was developed to examine predictors of weight on day of surgery. Baseline weight, diabetes status, diet duration and kcals/day were included in the model.


A total of 2,092 patients were included in the analysis. Diets ranged from <800kcal to >1200kcals/day and lasted one week to ≥5 weeks. The most common diets followed by patients were 800-1000kcals (55.7%) and lasted 2 weeks (71.4%). The unadjusted mean weight loss across all patients was 5.43kg (95% CI 5.18 to 5.68). Weight on the day of surgery was, on average, 0.79kg less for patients with diabetes compared to those without diabetes (p=0.002), and also less for 4 week (1.90kg, p=0.035) and ≥5 week diets (3.54kg, p=0.001), compared to a 1 week diet. Patients on a <800kcals/day diet were, on average, 8.86kg lighter than >1200 Kcals/day diets on the day of surgery (p=0.016). There was no significant difference in weight between VLED of <800kcal/day diets and LEDs of either 800-1000kcal/day (p=0.194) or 1000-1200kcal/day (p=0.212).


A range of pre-operative diets are used in clinical practice in the UK, reflecting a need for standardised guidance in this area. Our study found that lower kcal and longer duration pre-operative diets were associated with greater pre-operative weight loss. Further research is required to confirm our findings that patients with diabetes respond better to pre-operative diets and to establish the adequate level of weight loss as proxy for liver shrinkage prior to bariatric surgery.
Original languageEnglish
Article numberP1
Number of pages17
JournalObesity Surgery
Issue numberSupp 1
Publication statusPublished - 23 Oct 2021
Event2th BOMSS Annual Scientific Meeting - Oxford, United Kingdom
Duration: 27 Jul 202128 Jul 2021


Dive into the research topics of 'Efficacy of pre-operative'liver shrinking'dietary regimens: a UK national cohort study'. Together they form a unique fingerprint.

Cite this