Preparing for bariatric surgery
For patients scheduled for sleeve gastrectomy, gastric bypass or another bariatric operation. Follow these steps alongside your individual plan from Dr. Fady and the anaesthesia and nutrition teams.
Essential preparation
1–2 weeks before surgery
Stop eating bread, rice and pasta
- Bread
- Rice
- Pasta
Start 7–14 days before your operation, for the duration specified by Dr. Fady, and continue until the fasting time set by your anaesthetist.
This is part of the preoperative diet to reduce liver size and help access during laparoscopic surgery. Avoiding these foods alone does not replace the rest of your prescribed diet.
Food and fluids during preparation
- Follow the meals and portions prescribed by your team, including protein such as eggs, chicken, fish or dairy products suited to your plan, and permitted vegetables.
- Avoid sweets, sweetened drinks, juices and high-fat meals. Do not replace bread, rice and pasta with these foods.
- Drink water and permitted fluids according to your plan. Follow any fluid restriction prescribed for heart or kidney disease.
- Do not start complete fasting or a liquid-only diet yourself. If the team prescribes a specific plan, such as meal replacements, follow it as given.
- Contact the clinic before starting if you do not know your start date or which meals are allowed.
Tests and anaesthetic assessment
- Complete the tests requested by the team and send the results for review before your operation.
- Attend your anaesthetic assessment. Report medical conditions, allergies, previous anaesthetic problems and any history of blood clots.
- Bring previous operation notes, endoscopy reports and scans when available.
- Tell the team if you use a device for sleep apnoea and bring it to hospital if requested.
Review your medication
- Provide a complete list of medicines, doses, vitamins, herbal products and supplements.
- Obtain written instructions for diabetes medicines, insulin, blood thinners, antiplatelets and blood pressure medicines. Stop and restart times depend on your circumstances.
- Tell the team if you use Mounjaro, Ozempic, Wegovy, Saxenda or another weight-loss medicine. Include your last dose and any nausea, vomiting or bloating. Your team will set your medication and fasting plan.
- Do not stop prescribed medicines or change doses yourself. On the day, take only the medicines approved by your anaesthetist.
In the days before surgery
- Stop smoking, shisha and vaping as early as possible and tell the team if you are still using them.
- Keep active within your abilities and follow any prescribed breathing exercises.
- Inform the team promptly about fever, a new cough, infection, persistent vomiting, any important change in health or possible pregnancy.
- Confirm your hospital and arrival time. Arrange a companion, transport home and help after discharge.
Fasting and the night before
- Follow your anaesthetist’s written times for stopping food and fluids precisely. The cutoff for food may differ from the cutoff for water.
- Ask the team if fasting instructions are missing or unclear. Milk and juice with pulp are not water or clear fluids.
- Tell the team before anaesthesia if you have eaten or drunk after the specified cutoff.
- Shower as instructed by the hospital and pack comfortable clothes and personal essentials.
Before leaving for hospital
- Bring identification, admission paperwork and any required authorisations.
- Bring test results, scans, medical reports and your medication and allergy list.
- Bring your sleep apnoea device if you use one and have been asked to bring it.
- Make sure you know the food and fluid plan after discharge, prescribed medicines and supplements, follow-up date and contact number.
A question about preparation?
Contact the clinic team to confirm your diet dates, fasting instructions and medication plan before surgery.
Follow any individual instructions from Dr. Fady or your anaesthetist. This page covers preparation before surgery; your postoperative diet has different instructions.
Further reading on the preparation diet
Diet protocols vary between centres. Your clinic’s individual instructions determine your plan.
Chelsea and Westminster Hospital: liver shrinkage dietKeep a copy of your instructions
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