Bariatric Surgery

Bariatric Surgery - What is Bariatric Surgery?

Exercise and diet alone often fails to effectively treat people with extreme and excessive obesity. Bariatric surgery is an operation that is performed in order to help such individuals lose weight. Evidence suggests that bariatric surgery may lower death rates for patients with severe obesity, especially when coupled with healthy eating and lifestyle changes after surgery.

Principles of bariatric surgery

The basic principle of bariatric surgery is to restrict food intake and decrease the absorption of food in the stomach and intestines.

The digestion process begins in the mouth where food is chewed and mixed with saliva and other enzyme-containing secretions. The food then reaches the stomach where it is mixed with digestive juices and broken down so that nutrients and calories can be absorbed. Digestion then becomes faster as food moves into the duodenum (first part of the small intestine) where it is mixed with bile and pancreatic juice.

Bariatric surgery is designed to alter or interrupt this digestion process so that food is not broken down and absorbed in the usual way. A reduction in the amount of nutrients and calories absorbed enables patients to lose weight and decrease their risk for obesity-related health risks or disorders.

Body mass index (BMI)

Body mass index (BMI), a measure of height in relation to weight, is used to define levels of obesity and help determine whether bariatric intervention is required. Clinically severe obesity describes a BMI of over 40 kg/m2 or a BMI of over 35 kg/m2 in combination with severe health problems.

Health problems associated with obesity include type 2 diabetes, arthritis, heart disease, and severe obstructive sleep apnea. The Food and Drug Administration (FDA) approves the use of adjustable gastric banding for patients with a BMI of 30 kg/m2 or more who also have at least one of these conditions.

Types of Bariatric Surgery

There are various types of bariatric surgeries that can be performed. Surgery may be performed using an “open” approach, which involves cutting open the abdomen or by means of laparoscopy, during which surgical instruments are guided into the abdomen through small half-inch incisions. Today, most bariatric surgery is laparoscopic because compared with open surgery, it requires less extensive cuts, causes relatively minimal tissue damage, leads to fewer post-operative complications and allows for earlier hospital discharge.

There are four types of operations that are offered:

  • Adjustable gastric banding (AGB)
  • Roux-en-Y gastric bypass (RYGB)
  • Biliopancreatic diversion with a duodenal switch (BPD-DS)
  • Vertical sleeve gastrectomy (VSG)
Diagram of Surgical Options. Image credit: Walter Pories, M.D. FACS.

Each of the surgery types has advantages and disadvantages and various patient factors affect which procedure is chosen including BMI, eating habits, health problems related to obesity, and number of previous stomach surgeries. The patient and provider should discuss the most suitable option by considering the benefits and risks of each type of surgery.

Surgical and post-operative risks

People who have had bariatric surgery need to adhere to a rigorous and lifelong diet and exercise plan to prevent complications and to avoid putting on weight after surgery. In addition, patients may develop excess loose and folded skin that requires further surgery to remove and tighten.

As with all types of surgery, bariatric surgery is associated with risks including internal bleeding, deep vein thrombosis, infections, and pulmonary embolism (blood clot in the lungs). It is estimated that the risk of dying shortly after bariatric surgery is around 1 in 200.



Bariatric Surgery Side Effects

Bariatric surgery is a procedure performed on obese individuals in order to help them achieve rapid weight loss. The risks associated with bariatric surgery fall into two main categories: those related to restricted food intake and rapid weight loss and those associated with the surgical procedure itself.

Accordingly, side effects can be categorized as:

  • Immediate post-operative complications
    • Infection of the wound and of the operative site  (affects around 1 in 20 patients)
    • Internal bleeding (occurs in around 1 in 100 patients)
    • Development of blood clots (occurs in around 1 in 100 patients). Clots may develop in leg veins (deep vein thrombosis) or travel up to the lungs causing a pulmonary embolism, which can be life threatening.
  • Death

The immediate complications of bariatric surgery can result in a patient’s death. Pulmonary embolism, severe bleeding, major infection, stroke, or heart attack are all conditions that put the patient’s life at serious risk. The estimated risk of death after gastric band insertion is around 1 in 200 and after gastric bypass surgery, the risk is around 1 in 100.

Factors that raise the risk of dying due to post-operative complications include age, male gender, high blood pressure, increased risk for pulmonary embolism and a body mass index of 50 or above. Risks for pulmonary embolism include a history of pulmonary hypertension, deep vein thrombosis, and blood clots.

Development of gallstones

Gall bladder stones are a common outcome of bariatric surgery, with stones developing in around 1 in 12 individuals. Gallstones are aggregates of chemicals and cholesterol that eventually clog up the gall bladder. The stones may be symptomless or may cause intense pain in the abdomen as well as nausea, vomiting and jaundice.

Stoma blockage

Stoma blockage is a common complication of gastric bypass surgery that occurs when the opening (stoma) that connects the stomach pouch to the small intestine becomes blocked by a piece of food, resulting in persistent vomiting. The condition occurs in around one-fifth of patients and is treated by directing a small flexible tube called an endoscope into the stoma where a balloon attached to the endoscope is inflated to remove the obstruction. To avoid stoma blockage, food must always be taken in small bites and chewed thoroughly.

Excess skin

Rapid weight loss among obese individuals results in skin becoming excessively loose and folded. Folds of skin are most typically acquired around the breasts, back, abdomen, limbs, and hips and are normally most apparent 12 to 18 months after surgery. The folds can be unsightly and may harbour moisture leading to infections and rashes. These excess skin flaps can be removed and the skin tightened using cosmetic surgery.

Effects on mental health

Rapid weight loss may have a detrimental effect on mental health, with many patients suffering from depression and anxiety after surgery. Patients may also develop relationship problems with their partner. Additionally, social occasions orientated around meals may make the patient feel isolated and anxious due to their much reduced appetite and restricted diet.

Slippage of the gastric band

Gastric band slippage is a problem that affects around 1 in 50 patients who have had an adjustable band fitted. The band slips out of position and the stomach pouch becomes bigger than it should be, resulting in nausea, vomiting and heartburn. Further surgery is then required to repair the slippage.

Intolerance to foods

Food intolerance occurs in around 1 in 35 patients who have had bariatric surgery and may develop years after the procedure. Foods such as red meat may bring on heartburn, nausea and vomiting.



Bariatric Surgery Types

The type of bariatric surgery that is used to help extremely or morbidly obese individuals lose weight depends on a number of factors, with each type of surgery associated with advantages and disadvantages. Patients and healthcare providers need to discuss the risks and benefits of procedures before deciding on the most suitable type of surgery.

Open and laparoscopic surgery

An open surgery involves cutting open the abdomen and making modifications to the digestive tract. This involves making a single, large incision across the abdomen that may later take time to heal and may also lead to complications such as hernias.

A laparoscopic surgery involves distending the abdomen with an inert gas and making several small half-inch incisions across it to enable insertion of surgical instruments and a small camera that can be used to aid the operating surgeon. Today, most bariatric surgery is laparoscopic because compared to open surgery, it requires smaller incisions that heal faster, are associated with fewer post-operative complications (especially hernias) and allow for early hospital discharge.

However, not all patients are suitable for laparoscopy. Extremely obese individuals, those with complex medical problems such as severe heart and lung disease or those who have previously had abdominal surgery may require the open surgery approach.

Types of bariatric surgery

There are four types of operations that are commonly offered to patients:

  • Adjustable gastric banding
  • Roux-en-Y gastric bypass
  • Biliopancreatic diversion with a duodenal switch
  • Vertical sleeve gastrectomy

Factors that are considered when choosing the surgery include:

  • Benefits and risks associated with surgery type
  • Patient preference and willingness to adhere to the post-surgery dietary recommendations
  • Body mass index
  • Eating habits
  • Health conditions related to obesity
  • Previous stomach surgeries
Diagram of Surgical Options. Image credit: Walter Pories, M.D. FACS.
  1. Adjustable Gastric Banding (AGB)

The basic principle of this type of surgery is to decrease food intake with the use of a small bracelet-like band placed around the top of the stomach. The band restricts the size of the opening from the throat to the stomach, limiting the amount of food a patient can ingest. The size of the opening can be modified using a balloon inside the band that can be inflated or deflated with saline solution according to the needs of the patient.

  1. Roux-en-Y Gastric Bypass (RYGB)

This method is also used to decrease food intake and involves creating a small pouch that is similar in size to the pouch created with AGB. The food bypasses the rest of the stomach and reaches the small intestine, where it is absorbed to a much lesser degree than if it had passed through the stomach, duodenum, and upper intestine.

  1. Vertical Sleeve Gastrectomy (VSG)

This procedure involves removal of most of the stomach, which not only restricts food intake and absorption, but lowers levels of the hormone ghrelin that is responsible for appetite.

  1. Biliopancreatic Diversion with a Duodenal Switch (BPD-DS)

Also called the duodenal switch, this three-stage procedure involves the removal of a large part of the stomach which makes the patient feel full after eating only a small meal, followed by re-routing of the small intestines to prevent food absorption. The third step involves changing how bile and other digestive juices affect the process of digesting and absorbing calories.

Diet After Bariatric Surgery

Weight loss surgery involves reducing the capacity of the stomach to hold food, and therefore the amount of calories and nutrients that can be absorbed in the intestines. A patient’s diet needs to be modified accordingly after surgery to ensure maximum nutrition while reducing calorie intake.

A typical diet plan for a patient who has undergone bariatric surgery involves:

  • The stage 1 diet that is provided at hospital immediately after surgery. This initial diet comprises mainly liquids that the patient can slowly sip until the new stomach or stomach pouch is full.
  • The stage 2 diet is made up of low-sugar, liquid or semi-liquid foods such as warmed cereal with milk.
  • The stage 3 diet is designed for when a patient is discharged from hospital and includes semi-solid, pureed, and finally soft foods. The progress to soft food is slow to allow time for post-operative wounds in the stomach and intestines to heal.

Diet progression

Initial requirements include enough liquid to prevent dehydration and sufficient protein. Later, the diet needs to be adjusted to accommodate nutritional needs. The size of the stomach pouch is about one ounce and initially, as little as two to three teaspoons of food may make the patient feel full. Over time, the pouch stretches bit-by-bit to allow more food intake.

The diet’s composition

About three quarters of the patient’s calorie intake should come from protein sources such as eggs, fish and meat, while carbohydrates such as potatoes, rice and wheat should provide 10 to 20 % of the calorie intake, and fats between 5 to 15 %.

For the first six months, the diet should provide the patient with 800 to 1,000 calories and 75 grams of protein a day.

Foods to avoid

Foods containing sugars should be avoided, firstly because they may hamper weight loss and, secondly, because eating sugary food may lead to a condition called dumping syndrome, which describes when sugar moves directly from the stomach pouch into the small intestine where it can cause palpitations, nausea, abdominal pain and diarrhea.

Liquids should be avoided for a period of 30 minutes before and after eating solid food. When taken together with solids, liquids may cause nausea, as well as pushing food through the stomach pouch at a faster rate, leading to more eating than advised to satisfy appetite.

Overeating should be avoided at all costs. Overeating by even an ounce may induce nausea, vomiting or lead to stretching of the pouch.


Patients must maintain good levels of hydration, with 1 ½ to 2 liters of water consumed every 24 hours. This amount is to be increased by 20% if the patient is sweating. Carbonated beverages, soft fizzy drinks, sweetened drinks, and caffeine-containing drinks need to be avoided.

Maintaining nutrition

Due to the decreased food intake post-surgery, patients are at risk of vitamin and mineral deficiency and diet must be supplemented with multivitamins and minerals for the rest of the patient’s life.