Weight Loss Surgery

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Obesity is a disease where excess body fat has accumulated to the extent that it may adversely affect health.

The Body Mass Index (BMI), calculated as weight (in kilograms) divided by the square of height (in metres), is the recommended index to define obesity.

Classification of BMI in Asian adults.



Risk of co-morbidities




Normal Weight

18.5 to 22.9



23 to 27.4


Obese Class I

27.5 to 32.4


Obese Class II

32.5 to 37.4


Obese Class III


Very Severe

Patients who are morbidly obese (obese class III) have a much-reduced life expectancy compared to people of normal weight.

Calculate your BMI


There are no specific symptoms of obesity.
Obesity may cause the following problems:

When to Seek Treatment

When the BMI is in the obese range


During the consultation, the doctor will confirm that the patient has a high BMI and/or a high waist circumference. Specific tests to identify other medical conditions may also be needed.

Weight Loss Surgery and Obesity Treatments Option

Weight reduction can be achieved through various measures such as diet therapy, physical activity, behaviour therapy, and pharmacotherapy.

Bariatric Surgery, as part of a multi-discipliary approach is the most effective method for helping severely obese patients reduce weight.

[Colquitt JL , Pickett K , Loveman E , Frampton GK . Surgery for weight loss in adults . Cochrane Database Syst Rev 2014 : CD003641.]

There are different types of bariatric/weight loss procedures. They include

Adjustable Gastric Banding (AGB)

  • A collar of silicone containing an inflatable bladder is placed around the upper stomach.
  • Inflation is carried out by introducing saline via a special needle into a subcutaneous reservoir (port). This induces an earlier satiety and thereby decreases food intake
  • It also slows the passage of food from the upper pouch to the lower part of the stomach.
  • Patients who undergo adjustable gastric banding can lose 50-60% of their excess body weight.

Sleeve Gastrectomy

  • The stomach is reduced to about 15% of its original size.
  • This is a purely restrictive operation and eliminates the need to insert a foreign body.
  • However, this procedure does involve stomach stapling. Therefore leaks and other complications related to stapling may occur. It is also not reversible.

Gastric Bypass

  • This is a combined restrictive-malabsorptive procedure.
  • The operation includes forming a small stomach pouch and a small bowel bypass. This means that food bypasses the main part of the stomach and the upper part of the small intestine resulting in less calories being absorbed.
  • It has excellent and durable results with low morbidity and mortality rates.

Alternative intervention:

Intragastric balloon

  • A soft balloon is either swallowed or inserted into the stomach and filled with sterile saline.
  • This causes a feeling of satiety with resulting weight loss of about 15-20 kg.
  • The balloon will either be degraded or be removed after 4 months to a year.


Energy imbalances which causes the body to store fat
Some medical conditions such as hypothyroidism
Certain medications

Risk Factors

  • Unhealthy eating behaviours
  • Lack of physical activity
  • Family history

Consult Our Doctor

Dr Lim Khong Hee
Upper Gastrointestinal,
Bariatric & General Surgeon

MBBS (Singapore), M.Med (Surgery), FRCS (Edin), FRCSEd (Gen), FAMS (Surgery)

Bariatric Surgery or Weight Loss Surgery FAQs

The Body Mass Index (BMI), calculated as weight (in kilograms) divided by the square of height (in metres), is the recommended index to define obesity. Weight loss surgery should be considered for the treatment of obesity for acceptable Asian candidates with BMI ≥ 35 with or without other medical conditions. (IFSO-APC Consensus Statements 2011)

Although every surgical procedure will carry with it a certain amount of risks, weight loss surgery has been found to be one of the safest elective operations.

The three main types of weight loss surgery are gastric bypass, sleeve gastrectomy and adjustable gastric banding. Each of these procedures has different risks and potential weight loss. The choice of the procedure will depend on the individual patient’s factors such as coexisting medical conditions, BMI, expectations, etc.

You can lose between 20-25% of the total body weight at 5 years after the operation. The results will vary between patients. The amount of weight loss will also depend on how strictly you follow the dietary and lifestyle modification advice given.

Weight loss surgery for obesity alone is generally not covered by insurance in Singapore. However, some insurance plans may provide coverage for treatment of obesity-related medical conditions.

There is a staged approach to the dietary recommendations after weight loss surgery. The progression will be from liquids, pureed foods, and soft foods to solid foods. After 3 months, most patients can tolerate a regular diet comprising of small meals.

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