How does Gastric Sleeve surgery work?

There are two main types of surgery recommended by the surgical team. Gastric Sleeve and Gastric bypass. There is also a Mini Gastric Bypass procedure, but we do not compare it here.  Let’s look at the differences.

Gastric sleeve overview

A gastric sleeve is a surgical procedure that removes up to 80-85% of the stomach pouch. Less volume of food can be consumed in one sitting and as a result, the patient;

  • Can only eat small portions
  • Feels less hungry
  • Doesn’t think about food as often
  • Retains normal gastric processes(no bypass of stomach)
  • Feels fuller sooner and longer
  • Can lose a minimum of 75% of excess body weight within two years*
  • Can reverse or alleviate obesity-related illnesses or conditions

The gastric sleeve is not reversible but a
majority of patients report only positive
outcomes and they have no regrets,
especially given the new life being
embarked on. Recommended
for patients with a BMI of under 45.

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Gastric bypass overview

Gastric bypass is exactly how it sounds.  The procedure creates a new stomach pouch and reroutes the intestine bypassing the stomach.  As a result, the patient;

  • Can only eat small portions
  • Feels less hungry
  • Doesn’t think about food as often
  • Feel fuller sooner and for longer
  • Absorbs fewer calories into the body (malabsorption)
  • Can lose up to 65-67% of excess body weight within two years*
  • Can alleviate obesity-related illnesses and improve overall health

The bypass procedure is usually reserved for patients with a BMI of over 45 and is tried and true way for morbidly or super obese to lose weight, especially those who cannot incorporate exercise due to other ailments.

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Gastric sleeve overviewGastric bypass
Method of lossRestriction method (less food)Combines restriction (less food) with malabsorption
ProcedureSurgeon removes 80% of the stomach and creates a tube-like shaped stomach (sleeve) using titanium staplesSurgeon divides the stomach into a small upper pouch and large lower pouch and attached to the small intestine.
AnaestheticGeneralGeneral
Surgery methodLaparoscopic (keyhole) Minimally Invasive SurgeryLaparoscopic (keyhole) or Minilap (large incision)
Hospital stay2-3 days in hospital - minimum 5-7 days from surgery before cleared to fly2-3 days in hospital - minimum 5-7 days from surgery before cleared to fly
RECOVERYNormal activity within 6 weeksNormal activity within 6 weeks
PainManageable - Pain scale 3-4 for 1st 3 days (person dependent)Manageable - Pain scale 3-4 for 1st 3 days (person dependent)
Time off work1-3 weeks (depending on occupation)1-3 weeks (depending on occupation)
Risks short term
  • Reaction to anaesthetic
  • Staple line leaking
  • Bleeding
  • Stenosis/strictures
  • Digestion issues
  • Wound infection
  • Blood clots
  • Reaction to anaesthetic
  • Leaks in gastrointestinal system
  • Excessive bleeding
  • Blood clots
  • Infection
Risks Long-Term
  • Gastrointestinal obstruction
  • Hernias
  • Gastroesophageal reflux
  • Low blood sugar
  • Malnutrition
  • Vomiting
  • Bowel obstruction
  • Dumping syndrome
  • Hernias
  • Bowel obstruction
  • Gastroesophageal reflux
  • Low blood sugar
  • Malnutrition
  • Vomiting
  • Gallstones
  • Hernias
  • Malnutrition
  • Stomach perforation
  • Ulcers
Weight loss month 1Typically lose 2.5 to 7kg per week*Typically lose 2.5 to 7kg per week*
Weight loss month 333% of excess body weight or 29kg*33% of excess body weight or 29kg*
Weight loss month 650% excess body weight or 44kg*50% excess body weight or 44kg*
Weight loss month 1270% excess body weight or 62kg*65% body weight or 57kg*

How are the losses calculated?

When we say 50% of excess body weight, we mean the difference between what you
weigh NOW and the top of your healthy BMI range. For the examples in the table
above we used a 170cm, 160kg individual whose top healthy body weight should be
72kg. The loss required to get into the healthy range is 88kg. These types of losses
are indicative of the AVERAGE losses, some people lose less, some people much,
much more.

What are the reasons for the variance in weight loss?

Height: 170cm tall
Weight: 160kg – Excess = 88kg

  • Sticks to protein-rich foods as directed
  • Limits carbohydrates
  • Maybe has an alcoholic drink once a month
  • Does not eat a lot of empty calories such as bread
  • Tends to reward on one day a week with take away
  • Exercises 4 times per week for half an hour

RESULT AFTER 12 MONTHS – Lost 66kg or 75% of excess body weight.*

Height: 173cm
Weight: 183kg – Excess = 108.5kg

  • Mixes protein and carbohydrates in main diet
  • Tends to eat empty calories such as bread
  • Maybe has 1-2 alcoholic drinks per week
  • Tends to have a few chocolate treats per week
  • Consumes an additional 400-500 calories a day in liquids
  • Does not exercise other than normal functions

RESULT AFTER 12 MONTHS – Lost 52kg or 48% of excess body weight.*

Both patients had the same amount of stomach pouch removed, both patients hunger
hormones are muted and both patients can eat the same volume. Typically the person
who sticks to the plan provided to the patient is the one who will exceed the average
results and the person who goes outside of the recommendations may not achieve the
same results in the same amount of time.

Remember: 52kg is still an amazing result!

No weight loss after gastric surgery?

If you experience no loss at all, it has nothing to do with the surgery and has
everything to do with what is happening with caloric intake. Generally with 80-85% of
the stomach removed the maximum caloric intake will be around 1000 calories (it is nearly
impossible to eat any more than this consuming normal food). Anyone who only eats 1000 calories per day
WILL lose weight. This is not an opinion, this is a fact of science.

Basal Metabolic Rate

Everybody requires a minimum number of calories to live. This minimum number is
called the basal metabolic rate (BMR). Your BMR is the number of calories your organs
need to function while you perform no activity whatsoever. Think about sitting on the couch all day without moving.

  • Example A : Female, 35 years of age, 160cm tall, 115kg.
    Basal Metabolic Rate = 1887 calories
  • Example B: Male, 35 years of age, 170cm tall, 125kg.
    Basal Metabolic Rate = 2399 calories

So for the female in this example, the deficit, if you eat 1000 calories is 887 calories per
day and the male is 1399 calories per day. With the body in a caloric deficit, the fat stores become a target to meet the required BMR.

If you ‘drink’ your calories (there are many creative ways some people will still do this)
you can end up consuming more calories per day than you did pre-surgery and of
course, you will not lose weight! Someone who drinks 6 thick shakes, a few bottles of
wine or a melted tub of ice cream will not experience loss. Usually, people who drink
their calories have underlying issues (mental health) that need to be resolved in conjunction with
surgery. 99% of people who have this surgery fully use the tool
and gets their lives on track.

*Disclaimer: Results may vary from person to person

Sleeve or bypass?

A lot of patients wrestle with the choice of the sleeve or bypass. Once we submit
your details to the surgeon, he will make recommendations based on your personal
circumstances. See more detailed information about each procedure:

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