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Three things you should know about weight loss surgery before you contact a surgeon


Currently, I work with Mark Grant of Southern Weight Loss Surgery. He is a bariatric surgeon or, as I prefer, a weight loss surgeon.  I saw my first surgical patient when I worked in Scotland in 1998. I have had surgical patients on my caseload ever since.

Why do I prefer the term weight loss surgeon? Because I like plain language, not everyone will know what a bariatric surgeon does. Mark and I have discussed this, and he also likes the term “metabolic surgeon.”  I also like it because it changes the emphasis from what he does to why he does it.   Most people coming to see us will have “metabolic syndrome.” His surgery and the diet changes I support you to make are to reverse or manage this potentially life-shortening condition.

So what is Metabolic syndrome?

Metabolic syndrome is a condition that includes a cluster of risk factors specific to cardiovascular disease. The metabolic factors include

  • Abdominal obesity,
  • High blood pressure,
  • Impaired fasting glucose,
  • High triglyceride levels, and
  • Low HDL cholesterol levels.

Working with Southern Weight Loss, I see our patients before surgery and for up to two years post-surgery.

I also offer to see people who had surgery more than two years ago. I am happy to see those who have had surgery elsewhere and require dietetic support.

It may seem a paradox that I am working in weight loss surgery when I am a strong advocate of diet improvement without a focus on weight loss.

 Even if science tells me it is extremely difficult to lose weight and to keep weight off, some people want or need to lose weight. Loss of excess body fat will improve their health and quality of life. 

When counseling anyone in weight management, I am speaking about learning to accept the “good enough” effort. I will talk about learning to be kind to themselves and to improve their self-care. If there is lapse behavior, I will ask, “what happened” rather than being critical. This is the approach I take regardless of whether someone is having surgery.

 Currently, in New Zealand, we have very few options for weight loss. Very few of them are funded by the public system. This is an injustice, but sadly I do not see change occurring soon. This highlights how much education we need at all levels of society about the science of obesity. We must move away from seeing excess weight as about personal choice.


Who is eligible for weight loss surgery?

Weight loss surgery is an option for people with excess body weight who have tried and failed multiple times to lose weight through regular means. The guidance is that surgery is given to someone with a BMI of more than 40 if they have no health problems or a BMI of 35 if they have co-morbid health issues.

You and the surgeon discuss and decide on the right surgery for you. I will not go into details about the surgery here. Looking back at our data, around 1/2 of our patients have a sleeve gastrectomy (gastric sleeve). The other 1/2 have one of the bypass surgeries (Roux-en-Y or one anastomosis bypass).

As you can imagine, I have spoken with many people on their surgical journey. It is a major decision and investment if you are going privately for surgery.  Here are three things my surgical patients would have liked to have known. Before speaking to the surgeon, this knowledge would have helped them have an easier journey.

You will still be overweight when you reach your stable weight.

This is one of the most difficult conversations I have with people who see me. Many people want to get down to a normal BMI range because they have been told that that is a “healthy weight range.”   The reality is that BMI fails to look at individual differences.  If, as a person with a larger body, you have been carrying this extra weight around. You have built up extra muscle to carry that extra weight. 

Our goal is for you to lose body fat while retaining that extra muscle. This will help to maintain your metabolic rate.  We are starting with a higher lean muscle mass, which will affect the “ideal body weight.” 

When people use a BMI calculator on this “adjusted ideal body weight,” they are surprised to see their BMI remains in the overweight (BMI 25-29.9 kg/m2) or stage 1 obese category (BMI 30 to 34.9 kg/m2).

How can I be healthy without being in the healthy weight range?

I am often asked how this can be healthy, even by other health professionals.

Weight loss surgery aims to reduce cardiovascular and metabolic risk. We monitor blood pressure, cholesterol panels, and HbA1c. Most of these return to normal, with weight loss. Our goal is to keep them within the normal range.  It is worth knowing that sometimes people have genetic cholesterol. In this case, they will still need medication to manage their cholesterol levels, usually less than before surgery. Over time (15 to 20 years after surgery), some people develop type II diabetes.

Again, I am asked how this occurs and whether it is a surgery failure. One of the strongest but least recognized risk factors for type II diabetes is aging. People who have had surgery are getting 15 or 20 years of healthy life span. During this time, there is a reduced risk of type II diabetes and cardiovascular disease.

Some people want a lower body weight regardless of what I say. This can remain a tricky conversation because of some potential health risks of losing further weight. These include an increased risk of rebound weight gain and disordered eating.

After weight loss surgery, you will eat differently from everyone for the rest of your life.

When I book my first assessment, I send out an information page about the type of eating pattern that will endure after surgery. This is even after two years of post-surgical care. This is to help people start thinking about what a major change the surgery will bring to their diet. One of the pieces I include is the bariatric plate model.

You will see it is quite different from the regular plate model, which usually has 1/4 protein foods, 1/4 starchy foods, and 1/2 plate of vegetables.

This modified model highlights that there is a lifelong change in eating.

Immediately post-surgery, the stomach volume is around 1/4 C (60 ml). At the end of the two years, we expect a successful candidate to have a stomach volume of around 3/4 C (180ml). This means that you can eat up to this in one meal. The main point of difference is the need to eat protein first to achieve your protein goal.

This protein goal is advised at the initial appointment.  We talk about eating protein food first, then vegetables, and last starchy food. The carbohydrates are optional and only if you are not full after you have achieved your protein goal.


Supplements after weight loss surgery

All surgery patients need to commit to having a bariatric multivitamin every single day of their life after surgery.  Unfortunately, in New Zealand, we do not have bariatric-suitable multivitamins and minerals available on prescription. People in both the public and private health systems are required to self-fund this essential item.

Behavioral Changes

Behaviourally the big  changes are

  • Eating slowly (taking 20 minutes over a meal)
  • Chewing each mouthful well (a minimum of 20 chews) and
  • Not drinking fluids with the meal or within 30 minutes of the meal.

The other big change is regularly eating. For people after surgery, this means eating 5-6 times a day.


Why regular eating is so important after weight loss surgery

With the popularity of intermittent fasting, many people have a habit of going for long periods between eating. This must stop if you go for weight loss surgery. Although we encourage a window of 9 to 11 hours of not eating overnight spread, you will be eating 5 to 6 small meals spread across the day when you are eating.

This is the number one thing people struggle with during the two years after surgery.

The reason for frequent eating is to allow you to achieve your protein target. If you have a small stomach volume, you will not get enough protein on a three-meal-a-day pattern.

Some foods are the wrong texture after weight loss surgery.

The other change people find is what foods they can tolerate after surgery.

For some people, especially those who have bypass surgery, there will be foods they never manage to eat again. This is because the anastomoses (or hole) by which the food leaves the stomach and enters the small intestine is artificial. It remains small, so large and clumpy foods can get stuck in the anastomoses, causing unpleasant side effects. The most commonly not achieved foods are steak and white bread.

If you have disordered eating, it will still need to be managed even after weight loss surgery.

We know from the research that around 1/3 to ½ of people who presented weight loss surgery have diagnosable binge eating disorder. See the definition of binge eating disorder below.

Binge eating disorder is a complex condition and can be addressed with cognitive behavioral therapy. It is often rooted in the emotional response to weight bias or can be from learned behaviors to self-soothe from trauma and distress.

Of the rest of the patients, I see the vast majority will have a dieting mentality where they will often have strong judgments about good and bad food and will go for long periods without eating because they believe this will manage their body weight.  As you can imagine, if you need to shift from this irregular eating to eating 5 to 6 times a day, this is a big effort.

Most people seeing any dietitian for the first time will be so ashamed of the disordered eating that they will try and paint a good picture. This is not helpful. Having disordered eating will not necessarily exclude you from weight loss surgery, and managing the disordered eating will need to occur if you are going to have a successful outcome.

Why is managing an eating disorder so important?

We know from the research that roughly 50% of people return to a poor-quality diet within two years of the surgery. I suspect these people had a binge eating disorder beforehand and may not have admitted to it even during the postsurgical conversations.

It is sad because many people have experienced discrimination and oversimplification of body weight issues, even from dietitians, so having conversations about binge eating disorders or disordered thinking about food can be vulnerable making.

I would hope that my training around weight loss and my growing understanding of trauma would mean that it was a far less traumatic experience to discuss your eating-disordered behavior with me. This could occur either in the first appointment or if it becomes a problem after surgery. Screening for a binge eating disorder is problematic. While SCOFF is a simple tool, and there are binge eating disorder-specific tools such as BED-7, I think looking at an intuitive eating score is probably the most effective way of evaluating whether you are struggling with disordered thinking about food.

In another post, I will talk about managing binge eating disorders. It is useful to understand that we encourage eating 5 to 6 times a day and selecting foods that will sustain and nourish you in recovery from all eating disorders.

I will also go further into why binges feature ultra-processed foods and how these are identified as a significant problem for health across the population in future blogs.

I am currently in discussion with a psychologist colleague about whether or not we establish and run a binge eating group, either face-to-face in Dunedin or a virtual group, to help people work their way through this behavior regardless of whether they are thinking of weight loss surgery or not.

Get your support team onside.

If you are thinking of seeing a weight loss surgery, it is important to get your friends and family to support the decision.   There is still a wide perception that weight loss surgery is an easy option and that losing weight is as simple as eating less and exercising more. I will talk with family members about this for clients if they wish. It is easier to hear about the challenges that a loved one faces with their body weight from a professional sometimes.


The three things that my clients all say they wish they had known before surgery are

  1. Have realistic expectations about their end weight after surgery
  2. Think long and hard about how different your eating will be after surgery and for the rest of your life.
  3. If there is disordered eating, own up to it and get support. You will need to address it.


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I appreciate your thoughts about weight loss surgery and the challenges people face with larger bodies. If you or someone you know had surgery, was there anything else you wish you had known?