Preparing for Bariatric Surgery

Your Pre-Operative Journey

Bariatric surgery is one of the most significant health decisions you can make. Thorough preparation in the weeks and months before surgery reduces surgical risk, improves outcomes, and sets the foundation for long-term success.

This guide outlines the typical pre-operative process. Your surgeon and Dr Chong will provide instructions specific to your procedure and circumstances.

Pre-Operative Investigations

Before surgery is approved, a comprehensive assessment is required. This typically includes:

Blood tests:

• Full blood count, iron studies, vitamin B12, vitamin D, and folate
• Fasting glucose and HbA1c (diabetes status)
• Fasting lipid panel (cholesterol)
• Thyroid function
• Liver and kidney function tests
• Urine analysis

Other investigations:

• Sleep study — undiagnosed obstructive sleep apnoea is common in people with obesity and must be identified and managed before surgery
• Abdominal ultrasound — to assess the liver and gallbladder for stones or fatty infiltration
• Gastroscopy (endoscopy) — to check for H. pylori infection and any stomach or oesophageal conditions that may affect the surgical plan
• Chest X-ray and ECG — for cardiac and respiratory assessment
• Echocardiogram or exercise stress test — may be required if there are cardiovascular concerns

Allied health assessments:

• Dietitian review — to assess current diet and begin nutritional preparation
• Psychology assessment — to assess readiness for surgery, identify eating disorder patterns or mental health conditions that may affect outcomes
• Physiotherapy assessment — in some programs, particularly for patients with significant joint disease

The Pre-Operative Liver-Shrinking Diet

In the 2–4 weeks before surgery, you will be placed on a very low calorie diet (VLCD), also called the liver-shrinking diet. Following this diet strictly is one of the most important things you can do to prepare for safe surgery.

Why is it necessary?

In people with obesity, the liver commonly accumulates fat (hepatic steatosis). An enlarged, fatty liver sits over the stomach and significantly obstructs the surgeon's view and access. A pre-operative VLCD shrinks the liver by 20–30%, making the operation technically safer and easier.

What does it involve?

• Typically 2 meal replacement shakes or bars per day plus one small low-carbohydrate meal
• Very low carbohydrate intake — usually less than 50 g per day
• High protein intake to preserve muscle mass
• At least 2 litres of water per day
• No alcohol

Cheating on this diet risks surgery being cancelled on the day if the liver is found to be too large, or may require conversion from laparoscopic (keyhole) to open surgery. Follow it strictly.

Medications to Stop Before Surgery

Several medications need to be stopped or adjusted before surgery. Always follow your surgeon's and anaesthetist's specific instructions, as timing varies.

Commonly stopped 1–2 weeks before surgery:

• Blood thinners (warfarin, rivaroxaban, apixaban) — timing must be confirmed with your surgeon
• Aspirin and anti-inflammatory medications (NSAIDs) — ibuprofen, naproxen, diclofenac
• Combined oral contraceptive pill and hormone replacement therapy — increased blood clot risk perioperatively
• GLP-1 receptor agonists (semaglutide, liraglutide) — typically stopped 1–2 weeks before surgery due to delayed gastric emptying, which increases aspiration risk under anaesthesia

Medications generally continued until surgery day:

• Blood pressure medications
• Thyroid medications (taken with a small sip of water on the morning of surgery)
• Seizure medications
• Most psychiatric medications

Never stop any prescription medication without discussing it with your surgeon and Dr Chong first.

The Day Before Surgery

• Nothing to eat or drink after midnight (or as specifically instructed by your anaesthetist — some programs allow clear fluids until 2 hours before surgery)
• Shower with antiseptic soap if instructed
• Remove nail polish (allows the pulse oximeter to read correctly), jewellery, and piercings
• Arrange transport — you will not be permitted to drive after surgery
• Pack a hospital bag: loose, comfortable clothing; toiletries; reading material; phone charger; your medications list

Surgery Day: What to Expect

• Arrive at the hospital at the designated time (usually 2 hours before surgery)
• You will be admitted, weighed, and prepared by the nursing team
• You will meet the anaesthetist, who will explain the anaesthetic process and answer questions
• Your surgeon will review the plan and mark the operative site if required
• Surgery typically takes 1–2 hours depending on the procedure (sleeve, bypass, or band)
• Most procedures are performed laparoscopically (keyhole) under general anaesthesia
• After surgery, you will spend time in the recovery room before going to your ward
• Hospital stay is typically 1–3 nights

Preparing Emotionally

Surgery is not just a physical process. Emotional readiness is equally important:

• Inform close family members or support people, and ensure you have help at home for at least the first 2 weeks
• Understand that this is a lifelong commitment — surgery is a tool, and long-term success depends on the dietary changes, supplementation, and follow-up you maintain after the operation
• If you have concerns, anxiety, or unresolved questions, discuss them with your surgeon, Dr Chong, or the psychologist before surgery day