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A question we are often asked by our patients is whether or not they need to go on a diet before they have bariatric surgery. So today we thought we would explain the pre-surgery diet that we recommend to our patients and why.
Why do I need a special diet pre-bariatric surgery?
Although bariatric surgery is a very safe procedure, it is still major surgery and with all surgery, there are risks involved. The pre-bariatric surgery diet is designed to assist in making your surgery as safe as possible by increasing the amount of space in your abdomen to allow easier laparoscopic surgery.
When someone goes on a high protein Very Low Energy Diet (VLED) ½ the weight they lose comes from their abdomen. A 6kg weight loss will lead to an increase of 3 litres of intra-abdominal space for surgery to occur for example. This leads to less pain and faster recovery for you as internal cuts and bruising is less.
Other benefits;
- Patients with bad diabetes will get a reduction in their blood sugars which significantly reduces their risk of post-operative infections.
- Patients with sleep apnoea will reduce their risk of post-op breathing complications by over 50%
- Weight loss improves overall immunity
- Weight loss softens the abdominal wall, so if other issues such as hernias are found during surgery, they can be fixed without needing further surgery down the track.
- This diet allows people to try different formulations of VLED that they can use for the post-op diet.
How much weight someone “needs” to lose before surgery is different from person to person, however for many, 2 weeks on a VLED pre-op is sufficient to do the job. This equates to 4-8 kg for most people.
Special Cases
People with a BMI over 50 or weighing over 160-200 kg, those with significant and poorly controlled medical problems, and people who have had complex abdominal surgery before may need to lose a greater amount of weight before they can safely have surgery. In these circumstances we may set a specific weight target before surgery, with a plan to delay the procedure until the goals are met.
These goals may include, for example, achieving a 10% bodyweight reduction or getting to a certain nominated weight. In these circumstances the pre-op diet may need to be extended out to 4-12 weeks, depending on the goal.
What is the pre-bariatric surgery diet?
Our patients are asked to follow an intensive phase of VLED (very-low-energy-diet) or VLCD (very-low-calorie-diet), of three meal replacements and two cups of vegetables (sometimes an additional protein serve to ensure protein requirements are met if BMI is too high) for 2 weeks. Additional fibre and plenty of water are also advised during this VLED period.
The meal replacement that we often recommend to our patients is Optifast. It is a low carbohydrate, total diet replacement consisting of three Optifast products (meal replacement shakes or bars) that total 600-800 calories per day. Another really good product that we also recommend is Formulite, however any commercially available VLED will be OK as long as it has the protein and nutrients you need.
This diet puts patients into mild ketosis to help them lose weight rapidly, yet safely (on average 1.5 – 2.5kg per week). The low-carb nature is critical to success. Being in Ketosis forces us to burn glycogen and fat, but also suppresses hunger. Most other low energy diets promote hunger which isn’t very tolerated by most of us for more than a day or two.
It is important before you start on any diet to ensure that you have the approval of your doctor or dietitian, to avoid any nutritional deficits and to make sure you are losing weight safely.
Pre-op Diet Troubleshooting.
VLED’s or “diet shakes” are formulated foods. This means they have a number of natural and synthetic ingredients, and not everyone tolerates them or likes the flavours. It’s worthwhile for people to try different varieties before committing to the diet, not just to make the pre-op diet easier but also to make the post-op diet easier as well.
Common issues include
- Lactose intolerance which leads to wind and diarrhea in some people. There are lactose-free variants available (Tony Ferguson and some Vegan Shakes) however Lacteze tablets taken with the VLED will sort out most symptoms.
- Optifast Bars are an alternate for people who want a solid VLED or are lactose intolerant.
- Soy intolerance and artificial sweetener intolerance is an issue for some patients, in which case an individualised pre-op high-protein and low carb diet can be worked out with our dietician.
- Headaches/crankiness/hunger. The most difficult time of the diet is the first 24-48 hours when ketosis is “switching on”. Taking regular Panadol and avoiding stressful work over this time will help.
If you are considering bariatric surgery and would like to know more then contact our practice on (02) 9553 1120 or you can
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