About Obesity

Obesity, when used as a medical term, simply refers to people with a body mass index of greater than 30 kg/m².  Body Mass Index (or BMI) is a method of allowing for the fact that taller people will weigh more than shorter people, and is calculated by dividing a person’s weight in kilograms by the square of their height in metres.

 Obesity can further be graded according to BMI, with class II obesity being BMI greater than 35 kg/m², and class III being greater than 40 kg/m².

BMI Calculator

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BMI Categories

Am I a Candidate?

We know through experience and multiple medical studies that when a person has a BMI higher than 35 kg/m², it is exceptionally difficult to lose a meaningful amount of weight and keep it off.  This is where weight loss surgery fits in.

The original NIH criteria for weight loss surgery established in 1991 have recently been updated as the ASMBS/IFSO Guidelines 2022. These have extended the traditional criteria for bariatric surgery to include all people with a BMI of higher than 35 kg/m² regardless of health status, as well as people with a BMI of between 30 and 35 kg/m² if they have type 2 diabetes or have been unable to sustain substantial weight loss or health improvement using non-surgical methods.

At Aspiring Bariatrics Laparoscopy and Endoscopy Limited our criteria for undergoing weight loss surgery are:

  • Longstanding class II or greater obesity (BMI > 35 kg/m²)
  • Previous unsuccessful attempts at weight loss
  • Understanding of the risks and benefits of surgery
  • Prepared to comit to the life long lifestyle changes and follow-up required for weight loss surgery
  • Acceptable risk for surgery
  • No untreated medical, psychiatric or substance abuse issues

Weight loss surgery may also be indicated for people with a BMI of 30 – 35 kg/m² if the suffer from type 2 diabetes or have been unable to achieve sustained weight loss and health improvement with non-surgical weight loss attempts.

We offer a comprehensive multi-disciplinary assessment for all patients interested in weight loss surgery including medical assessment, nutritional assessment, diagnostic sleep testing and laboratory studies. Following this assessment we offer a choice of laparoscopic weight loss surgery operations in a modern, state of the art facility.

Roux-en-Y Gastric Bypass

The ‘gastric bypass’ is the second most common weight loss operation performed worldwide.  It has been performed since the 1960’s as an open operation, and laparoscopically since 1993.

In this operation the stomach is partitioned in to a small stomach pouch approximately 30mLs (two tablespoons) in size.  The small intestine is joined directly to this pouch and rejoined to itself in a ‘Y’ shape approximately 1m further down.  This results in people feeling much less hungry, and feeling satisfied after eating a very small portion of food.  On average, people will lose 25-35% of their starting body weight in 12-18 months (e.g. someone weighing 150kg may lose 37-53kg).  Gastric bypass may also have a specific anti-diabetes effect due to bypassing the upper small intestine.

Gastric bypass

Roux-en-Y Gastric Bypass.
Copyright ©2012 Covidien. All rights reserved. Reproduced with the permission of Covidien Pty Ltd.

Details and Risks

Laparoscopic Roux-en-Y gastric bypass is performed under a general anaesthetic (you are completely asleep). Usually people are in hospital for two nights after surgery, and go home tolerating a liquid diet and able to move about and care for themselves. After gastric bypass, certain vitamins and minerals are not absorbed as well because of the bypassed intestine. It is necessary therefore to take vitamin supplementation for life (multivitamin, calcium, iron). Gastric bypass is a major operation, and as with any operation, carries risks of potentially serious complications. However, in experienced hands, the modern laparoscopic Roux-en-Y gastric bypass is very safe, and the risks are comparable with having a major joint replacement operation. The risks of serious complications, requiring return to the operating room or intensive care admission are approximately 2 in 100. The risks of dying as a result of complications are 1 to 3 in 1000.

Gastric bypass is a permanent change to the digestive tract, and as such there are risks of late complications that may occur months or years after surgery. The most common is a stricture or narrowing at the join between the stomach pouch and small intestine. This usually occurs in the first six months after surgery, and can usually be treated with a single endoscopy (telescopic examination of the stomach). In people who smoke cigarettes, or take aspirin or anti-inflammatory drugs, this complication can be more severe, and very difficult to treat. Therefore, gastric bypass is not recommended in these circumstances. Blockages to the intestine may also occur because of the way the intestines have been rearranged. This may occur in approximately one in twenty people who have a gastric bypass. Surgery is usually required to treat this, however this surgery is usually relatively straightforward, and is not usually an emergency.

One Anastomosis
Gastric Bypass

The ‘One Anastomosis Gastric Bypass’ is a variation of the Roux-en-Y gastric bypass where there is just one join with the intestine rather than two.  It is a relatively recent procedure that is also sometimes called a loop gastric bypass, omega loop gastric bypass or mini gastric bypass.

Similar to the Roux-en-Y gastric bypass this operation works by helping people to feel much less hungry, and feel satisfied after eating a very small portion of food.  It has a similar effect on diabetes as well.

Gastric bypass

One Anastomosis Gastric Bypass.
Copyright ©2012 Covidien. All rights reserved. Reproduced with the permission of Covidien Pty Ltd.

Details and Risks

One anastomosis gastric bypass is also usually performed using laparoscopic or keyhole surgery.  Globally, it still accounts for a reasonably small proportion of all weight loss operations, and there is less long term outcomes data than there is for Roux-en-Y gastric bypass or gastric sleeve.  Compared to the Roux-en-Y gastric bypass, the one anastomosis gastric bypass may offer slightly greater average weight loss and slightly better control of diabetes.  The tradeoffs are that it probably results in greater malabsorbtion and more vitamin deficiencies than Roux-en-Y gastric bypass, and can cause abdominal pain from bile reflux in some people requiring a second operation to convert it to a Roux-en-Y configuration.

Gastric Sleeve

The gastric sleeve or sleeve gastrectomy is a relatively new weight loss operation that has been performed since 2000, but is now the most commonly performed weight loss operation worldwide.  It involves removing 4/5ths of the stomach to turn it from a reservoir for food in to a narrow tube or sleeve.  Weight loss outcomes between 3- and 5- years after sleeve gastrectomy are similar to those after a gastric bypass.  On average, people will lose 20-30% of their starting body weight in 12-18 months (e.g. someone weighing 150kg may lose 30-45kg).  

Similar to a gastric bypass, the sleeve gastrectomy acts to interfere with the signals of hunger and satisfaction between the brain and the intestine, so that people feel satisfied after eating a small portion of food. The sleeve gastrectomy also limits the amount of food a person is able to eat in a sitting, however as no intestine is bypassed, there is no reduction in absorption.

Gastric Sleeve

Gastric Sleeve.
Copyright ©2012 Covidien. All rights reserved. Reproduced with the permission of Covidien Pty Ltd.

Details and Risks

The sleeve gastrectomy is usually performed using laparoscopic or ‘keyhole’ surgery. It is performed under a general anaesthetic, and hospital stay is usually one night after surgery. Discharge diet and follow-up schedule are the same as that of a gastric bypass. As people are on a highly energy restricted diet after sleeve gastrectomy, vitamin supplementation is still recommended. However, the consequences of not taking these vitamins are not as critical as with a gastric bypass.

Laparoscopic sleeve gastrectomy has similar risks to that of gastric bypass. Overall, the risk of complications around the time of surgery is low, but serious complications may occur. With sleeve gastrectomy, there is a risk of leakage at the line of staples that is used to divide the stomach. Although the risk of this occurring is similar to the risk of leaking at the joins after a gastric bypass, it is a more difficult complication to treat after sleeve gastrectomy. If this occurs, it may require a hospital stay of many months, with repeat operations, and feeding via IV lines or tubes instead of by mouth.

Sleeve gastrectomy is also a permanent change to digestion, and as part of the stomach has been removed this operation cannot be reversed. Late complications include narrowing of the sleeve, and development of reflux or heartburn. Up to one in three people will need to take medications for reflux (or have surgery for this) after sleeve gastrectomy. Ulcers, blockages to the intestine, and vitamin deficiencies however are very uncommon after gastric sleeve.

Why Choose Us?

Here at Aspiring Bariatrics we know what a significant, life changing decision it is to undergo weight loss surgery, and how important it is to put your care in the hands of a team you can trust. Dr Smith is Otago and Southland’s most experienced weight loss surgeon and he and his team have your safety as their top priority.

Our experienced team knows just how important multi-disciplinary follow up care is to achieving the best outcomes after weight loss surgery. In addition to his Dunedin consulting, Dr Smith offers regular in person clinics in Invercargill and Queenstown to make these face to face visits easier for people living elsewhere in our region. He and his team consistently ensure that the wrap around care package incorporates the latest international best practice to help you achieve your objectives.

Dr Smith and the whole team at Aspiring Bariatrics have been helping people in Otago and Southland achieve their weight loss surgery goals since 2012. To find out how we can help you achieve yours, please contact us.

Dr Mark D Smith

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PO Box 6276, Dunedin North, 9059