Weight loss surgery

Weight loss surgery is also known as bariatric surgery. It aims to reduce weight and improve medical conditions which are associated with obesity.1

A man smiling at the camera who had undertaken weight loss surgery

Who qualifies for weight loss surgery?

Your doctor may consider you for bariatric surgery if these conditions apply to you:2

  • Your BMI is over 40.
  • Your BMI is over 35 and you have a comorbidity that may improve with weight loss.
  • Your BMI is over 30 and you have uncontrolled type 2 diabetes and at increased cardiovascular risk.

You must show that you’re committed to making lifestyle changes and you need to understand the risks of surgery and agree to followup care.

Disclaimer: Consult your doctor for weight management and get help to work out what weight loss plan is best for you.

How does bariatric surgery work?

Weight loss surgery works by increasing the feeling of fullness after you eat.3 4

Most weight loss surgeries in New Zealand are performed laparoscopically. That means they’re key-hole surgery.5

When you have key-hole surgery, you usually spend less time in hospital, have fewer complications and it takes less time to make a full recovery compared to open surgery.6 7 8

The average length of stay in hospital for patients after bariatric surgery is between 1.9 and 2.8 days, depending on which procedure you have done.9

Types of bariatric surgeries

Sleeve gastrectomy or gastric sleeve surgery

72% of weight loss surgeries in 2018/19 were sleeve gastrectomy.10

Your surgeon uses a stapling device to create a ‘sleeve’ in your stomach and removes the rest of the stomach.

Your stomach will hold only about a fifth of what it used to.11

Roux-en-y gastric bypass surgery

10% of weight loss surgeries in 2018/19 were roux-en-y- gastric bypasses.10

In this surgery, your surgeon will use staples to create a small pouch in the top part of the stomach.

The pouch sends nutrients straight to the small intestine, bypassing most of the stomach and making you feel fuller.11

One anastomosis gastric bypass surgery

7% of weight loss surgeries in 2018/19 were one anastomosis gastric bypass surgeries, sometimes called mini gastric bypass surgery.10

Your surgeon will create a gastric pouch which joins to the loop of the intestine.

It’s considered a less complicated version of the roux-en-y gastric bypass.12

How well does bariatric surgery work for weight loss?

Of all the weight loss strategies, studies have shown that surgery leads to the greatest and most sustained weight loss for people with obesity.2 13

After three years, the average weight loss is 24%. By 5 years, the average weight loss is 19%.10

There are other health advantages too. 31-77% of people with type 2 diabetes manage normal blood sugar without diabetes medication after weight loss surgery. 80% maintain good glycaemic control with reduced or no medication.14

Other reported improvements include:1 14 15 16

  • Lower cardiovascular risk factors (stroke, high blood pressure, high cholesterol)
  • Improved kidney function
  • Reduced respiratory diseases such as asthma and sleep apnoea
  • Less reflux disease
  • A better quality of life

What are the risks of weight loss surgery?

Like any medical intervention, bariatric surgery has risks, including the risk of surgical failure, complications, even in rare cases, death.1 16

Of the over 70,000 patients in Australia and New Zealand who have had surgery since 2012, 0.8% had to have another operation to fix a problem. Less than 1% have been re-admitted to hospital with a complication.10

In 2018-19, the rates of adverse events ranged from 1.6% (sleeve gastrectomy) to 6.3% (roux-en-y gastric bypass surgery).10

What should you consider before thinking about weight loss surgery?

Bariatric surgery is not a quick fix. You need long term commitment to get the best outcomes.

You will need to make substantial lifestyle changes before your surgery. This might mean giving up smoking and most patients will need to use meal replacements for 2-4 weeks beforehand to increase safety of the surgery.1

After your weight loss surgery, you will have to follow a healthy lifestyle plan and you will need to take vitamin and mineral supplements for the rest of your life. It’s important that you work on your mental health and get help if you need it, as it will increase your chances of success.17

Obesity is a chronic and progressive disease and there is a high likelihood that you may regain some weight at some point. If you stay connected with your healthcare team, you can help minimise weight gain and live a healthy, active lifestyle.1

Watch some patient stories

The research behind the science

1 National Health and Medical Research Council (2013). Clinical practice guidelines for the management of overweight and obesity in adults, adolescents and children in Australia. Available at https://www.nhmrc.gov.au/about-us/publications/clinical-practice-guidelines-management-overweight-and-obesity, accessed September 2019.

2 ANZOS and ADS. 2020. The Australian Obesity Management Algorithm. Available at: https://static1.squaresp ace.com/static/5e3b5875edc1485d14d6fe3a/t/5f333410b37c0216c50936dc/1597191187793/Australian+Obesity+Management+Algorithm+update_22Jun2020.pdf . Accessed December 2021.

3 Dimitriadis, G. K., Randeva, M. S., & Miras, A. D. (2017). Potential Hormone Mechanisms of Bariatric Surgery. Current obesity reports, 6(3), 253–265. doi:10.1007/s13679-017-0276-5 https://link.springer.com/article/10.1007%2Fs13679-017-0276-5

4 Batterham R.L., Cummings D.E. Mechanisms of diabetes improvement following bariatric/metabolic surgery, 2016 Diabetes Care, 39 (6), pp. 893-901. https://diabetesjournals.org/care/article/39/6/893/29560/Mechanisms-of-Diabetes-Improvement-Following

5 AIHW National Hospital Morbidity Database Australian refined diagnosis-related groups (AR-DRG) data cubes. Version 8.0, 2017-18. https://www.aihw.gov.au/reports/hospitals/ar-drg-data-cubes/contents/data-cubes. Accessed December 2019

6 Das B, Khan O. The myths of obesity. Int J Surg 2019; 68: 114–16. https://www.sciencedirect.com/science/article/pii/S1743919119301529

7 Banka G et al. Laparoscopic vs Open Gastric Bypass Surgery Differences in Patient Demographics, Safety, and Outcomes. Arch Surg. 2012;147(6):550-556.

8 Reoch J et al. Safety of Laparoscopic vs Open Bariatric Surgery – A Systematic Review and Meta-analysis. Arch Surg. 2011; 146 (11):1314-1322.

9 Ramos A, et al. The International Federation for the Surgery of Obesity and Metabolic Disorders Fifth IFSO Global Registry Report 2019. Available at https://www.ifso.com/pdf/5th-ifso-global-registry-report-september-2019.pdf, accessed December 2019.

10 Monash University. Bariatric Surgery Registry 2018–19 Report. Available at www.monash.edu/medicine/sphpm/registries/bariatric, accessed September 2019.

11 Lee P, Dixon J, RACGP Bariatric–metabolic surgery: A guide for the primary care physician July 2017 46(7), Available at https://www.racgp.org.au/afp/2017/july/bariatric-metabolic-surgery-a-guide-for-the-primar Accessed December 2021

12 Carbajo MA, Luque-de-León E, Jiménez JM, Ortiz-de-Solórzano J, Pérez-Miranda M, Castro-Alija MJ. Laparoscopic One-Anastomosis Gastric Bypass: Technique, Results, and Long-Term Follow-Up in 1200 Patients. Obes Surg. 2017;27(5):1153-1167. doi:10.1007/s11695-016-2428-1 https://link.springer.com/article/10.1007/s11695-016-2428-1

13 Schwartz M, et al. Endocrine Rev 2017; 38: 267–96.

14 érez-Pevida B, Escalada J, Miras AD and Frühbeck G (2019) Mechanisms Underlying Type 2 Diabetes Remission After Metabolic Surgery. Front. Endocrinol. 10:641. doi: 10.3389/fendo.2019.00641

15 De Luca M, et al. Obes Surg 2016; 26(8): 1659–96.

16 Pareek M, et al. J Am Coll Cardiol 2018; 71(6): 670–87.

17 Karasu S, Psychotherapy-Lite:Obesity and the Role of the Mental Health Practitioner American Journal of Psychotherapy2013 67:1, 3-22 https://psychotherapy.psychiatryonline.org/doi/10.1176/appi.psychotherapy.2013.67.1.3