When pursuing bariatric surgery, many thoughts can circulate in your head – eating after surgery, exercising, post-operative pain – but one of the biggest concerns is the dreaded pre-op diet. A quick internet search on bariatric pre-op diets shows that no two are alike. One thing that cannot be stressed enough: every surgeon and every clinic has their own pre-op diet. Follow their diet and guidelines, as this is what they have found to be best for their patients.
Key takeaways
- Pre-op diets vary from a few days of clear liquids to months of nutrition visits or a very low-calorie diet.
- A main purpose is to reduce the size of the liver, making surgery safer.
- Losing just 9.5% of excess body weight before a gastric bypass reduced post-operative complications.
- Start a multivitamin and mineral supplement during this time.
Length of the pre-op diet
Pre-op diets can range from:
- a few days of a clear liquid diet;
- full liquids for a few weeks;
- a programme with several months of nutrition visits and weight checks;
- a very low-calorie diet (VLCD, 800 calories a day or less).
Although each diet looks different, one of the main purposes of each is to reduce the size of your liver. An enlarged, fatty liver has been shown to complicate bariatric surgery, and it is estimated that 75–100% of bariatric patients have non-alcoholic fatty liver disease.3,4 An enlarged, fatty liver can obstruct access and increase the risk of bleeding during surgery, due to the friability of the liver tissue.
Reason for the pre-op diet
These restricted diets are necessary for more than just reducing liver size. A large-scale study showed that gastric bypass patients who lost just 9.5% of their excess body weight (EBW) had fewer post-operative complications, including anastomotic leaks, deep infections and minor wound complications.1 Pre-op weight loss has been shown to improve weight loss and liver function at 6 months post-op4 and can even help reduce surgery time.1
Changes surrounding the pre-op diet
The benefits of following the restricted diet your surgeon and dietitian give you outweigh the drawbacks. However, these restrictions can make it difficult to meet all your nutritional needs through diet alone, so it is recommended that you also start a multivitamin and mineral supplement during this time.2 A visit with a registered dietitian before your procedure can help improve and correct any nutritional deficiencies before surgery, and answer your questions about your pre-op diet.
Other changes that might be introduced with your pre-op diet:
- Switching to decaffeinated drinks
- Stopping smoking and alcohol
- Stopping hormonal contraception
- Avoiding NSAIDs
- Lifestyle changes, such as taking small sips of non-sugary drinks throughout the day
Your surgeon and bariatric team will discuss all these changes with you before you start them. They are there for a reason, so follow their instructions closely.
Sources
- Dagan SS, et al. Nutritional recommendations for adult bariatric surgery patients: clinical practice. Advances in Nutrition. 2017;8(2):382–394. doi:10.3945/an.116.014258
- Parrott JM, et al. The optimal nutritional programme for bariatric and metabolic surgery. Current Obesity Reports. 2020. doi:10.1007/s13679-020-00384-z
- Van Wissen J, et al. Preoperative methods to reduce liver volume in bariatric surgery: a systematic review. Obesity Surgery. 2015;26(2):251–256. doi:10.1007/s11695-015-1769-5
- Wolf RM, et al. Impact of a preoperative low-calorie diet on liver histology in patients with fatty liver disease undergoing bariatric surgery. Surgery for Obesity and Related Diseases. 2019;15(10):1766–1772. doi:10.1016/j.soard.2019.08.013
This article is for general information only and does not replace personal medical advice. Always discuss your situation, blood test results and supplementation with your bariatric team or healthcare provider.