Bariatric Surgery: Types, Benefits, Complications

Bariatric surgery, types, benefits and complications written in black box on picture of fat man's belly and hand stop

Bariatric surgery is an operation to help very obese people lose weight. It is also called weight loss or metabolic surgery. Basically, the principle is to inhibit people from eating too much and/or decrease the absorption of food in the body. What happens is that, sometimes, some people do not lose weight with exercise and a proper diet. Consequently, they can opt for bariatric surgery.

Problems with obesity

Over the past five decades, the rate of obesity has peaked alarmingly. As it currently stands, one-third of the world population is actually overweight or obese. Obesity is a significant health threat as it affects the whole body system from heart issues to mental health.

Additionally, it affects the quality of life, work productivity and healthcare costs. For instance, the total direct and indirect costs related to obesity is equivalent to 0.47 to 0.61% of the total GDP in Europe.

bariatric surgery, obese man on blue background holding head thinking though callout with words written: diabetes, depression, decreased work productivity, cardiovascular problems, lack of self esteem, sleep apnea
Problems associated with obesity

What is obesity?

According to the WHO, obesity and overweight is the excessive or abnormal accumulation of fat in the body that poses health risks. We use the Body Mass Index (BMI) as a simple metric to indicate overall body fatness. It is an equation that divides the body weight in kilograms by the square of height in meters.

The WHO states that a normal BMI for an adult is in the range of 18.5 to 24.9 kg/m2. Thus, those who have a BMI equal to or above 25 kg/m2 are overweight, a BMI equal to or above 30 kg/m2 are obese and a BMI equal to or above 40 kg/m2 are severely obese.

What causes obesity?

All in all, obesity is the result of an excessive amount of energy intake compared to energy use. This excess energy is stored in adipose tissues which become bigger and bigger, thus leading to weight gain.

Generally, obesity is the result of consuming energy-dense and nutrient-poor foods and beverages. As processed food becomes more affordable, people tend to overconsume them. At the same, they undertake very little to no physical activities at all, thus compounding obesity.

Who is at risk of obesity?

Obesity can occur in children to adults irrespective of age, sex, ethnicity and location. In developing countries, it is mostly the rich, middle-aged people who are obese, especially women. In contrast, in developed countries, it affects all ages and both sexes, though disadvantaged groups are more at risk.

Treating obesity

As more and more people are getting obese around the world, it is crucial for us to find solutions to treat and/or prevent it.

Basically, we treat obesity by making changes in our lifestyles, using drugs and surgery.

1.      Making changes in our lifestyles

By making some changes in our lifestyles, we can indeed prevent weight gain. This includes eating healthy, balanced meals that make us feel full on less food. We can also opt for unprocessed foods, make healthier choices as well as restrict certain foods like desserts.

And, very importantly, we must boost our physical activity levels.

Unfortunately, we can only lose weight by 2-6% with lifestyle changes. Studies show that after 1-5 years, almost 90% of patients may return back to their original weight or even gain more.

bariatric surgery, red and green watermelon slices on wooden chopping board and steel knife
Changing lifestyles such as cutting on desserts for fresh fruits can decrease obesity problems; Image from Needpix

2.      Using drugs

Alongside lifestyle changes, sometimes some people can use drugs (medications) to treat obesity. These drugs principally prevent the person from feeling hungry or make him/her feel full. A doctor will prescribe specific medications based on a person’s health.

The main goal of using drugs is to stick to a low-calorie diet.

However, people who use drugs lose only some 5-15% of their original weight. And patients are rarely satisfied with the results in the long term.

3.      Surgery

Thus, ultimately, patients can go for weight loss surgery. There are various types of weight loss surgeries that have both advantages and disadvantages.

Certain operations prevent people from eating too much food. Others alter the way the body digests and absorbs food.

Bariatric surgery has proved to be an effective treatment compared to non-surgical methods. People can lose weight by 15-30% in the long term depending on the type of operation.

However, bariatric surgery costs a lot, usually in the range of $20,000 to $35,000.

Eligibility for bariatric surgery

Studies show that bariatric surgery is quite an effective and durable treatment for obesity. Nonetheless, health institutes have set in place some important eligibility criteria for this operation.

So, people who can have bariatric surgery must either

  • Have a BMI between 35 and 40 kg/m2 plus an obesity-related complication. Examples are diabetes, high blood pressure or sleep disorders.
  • Or, a BMI of more than 40 kg/m2, regardless of any health complications.

Types of bariatric surgery

There are four main types of bariatric surgery: laparoscopic adjustable gastric banding (AGB), Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG) and biliopancreatic diversion (BPD).

1.      Adjustable gastric banding (AGB)

The principle of the adjustable gastric banding is to feel full with less food. To achieve this, surgeons decrease the size of the stomach.

They thus place an adjustable silicone band around the stomach, forming a small 15-30 mL pouch towards the top. This band is connected to a small device under the skin, usually near the chest. Consequently, doctors can adjust the size of the pouch by injecting or removing saline water in the device.

2.      Roux-en-Y gastric bypass (RYGB)

In a gastric bypass, surgeons staple a small section of the stomach to form a small pouch. They then connect it directly to the small intestine, bypassing the rest of the stomach.

Consequently, the food no longer goes into certain parts of the stomach and small intestine. As a result, the body does not absorb as many calories from the eaten food.

3.      Sleeve gastrectomy (SG)

In the case of sleeve gastrectomy, surgeons remove a large part of the stomach (75%) making it much smaller. They conserve the valve at the bottom of the stomach so that stomach functions remain the same.

At the end, the stomach becomes the size of a banana. Consequently, people can only eat small amounts of food and feel full sooner.

This process is not reversible and can be the first stage for a gastric bypass.

4.      Biliopancreatic diversion (BPD)

As for the biliopancreatic diversion, surgeons remove a part of the stomach allowing an upper 200-250 mL pouch. They then connect this pouch directly to the final part of the small intestine, bypassing the upper parts.

They also create a common channel to allow bile and pancreatic juices to mix with digested food before it enters the colon.

People lose weight in this way as most calories go into the colon where they are not absorbed.

Is bariatric surgery safe?

Each of the above mentioned type of bariatric surgery has its owns benefits and risks.

Nevertheless, bariatric surgery is generally safe to undertake with 30-day mortality rates ranging from 0.1-1.1% depending on the procedure. Nonetheless, people who are especially vulnerable, like those with severe obesity, must undergo careful risk evaluation before surgery.

Benefits of bariatric surgery

  1. Decreases type 2 diabetes
  2. Improves cardiovascular health
  3. Improves joint pain
  4. Stops sleep apnea
  5. Decreases depression
  6. Provides long term weight loss
  7. Decreases deaths
  8. Treats other health conditions like dyslipidemia, cancer and urinary incontinence

Complications of bariatric surgery

  1. Infections
  2. Formation of gallstone
  3. Nutrient deficiencies
  4. Inability to eat certain foods
  5. Intestinal obstruction
  6. Dumping syndrome (dizziness and nausea)
  7. Excess of hanging skin
  8. Causes other health issues like anemia, acid reflux, hernia

What is the most common type of bariatric procedure?

Before a person can have bariatric surgery, a specialist will first assess his/her health based on various criteria. This can include blood tests, eating patterns and mental health conditions.

In general, the most common type of bariatric procedure that doctors perform is sleeve gastrectomy by 61%. Then we have the Roux-en-Y gastric bypass which accounts for 17%. Adjustable gastric banding and biliopancreatic diversion are less common (less than 2%) as they pose more health complications.

What makes bariatric surgery successful?

Broadly speaking, bariatric surgery has high success rates with patients maintaining weight loss in the long term. Nevertheless, as the number of potential candidates for surgery increases, there is a lack of experts with sufficient expertise to perform these operations.

Also, some eating disorders may persist after surgery thus resulting in weight gain. And those who suffer from active depression may also fail to maintain their weight.

Generally, the successful patient is the one who changes his/her lifestyle and eating patterns together with surgery. As some health complications may eventually develop, health monitoring must be ongoing.

Which is the best bariatric surgery for me?

In light of the above information, there is no best treatment for all patients. Each person’s body, health and mental state differs. Additionally, each bariatric procedure has its own short term and long term benefits and risks.

Therefore, each person must carefully consider his/her own preferences and values with an expert.


  1. Arterburn, D.E., Telem, D.A., Kushner, R.F. and Courcoulas, A.P., 2020. Benefits and risks of bariatric surgery in adults: a review. Jama, 324(9), pp.879-887.
  2. Le Roux, C.W. and Heneghan, H.M., 2018. Bariatric Surgery for Obesity. The Medical Clinics of North America, 102(1), pp.165-182.
  3. Lee, G.K. and Cha, Y.M., 2016. Cardiovascular benefits of bariatric surgery. Trends in cardiovascular medicine, 26(3), pp.280-289.

5 Comments on “Bariatric Surgery: Types, Benefits, Complications

  1. Pingback: BARIATRIC SURGERY: TYPES, BENEFITS, COMPLICATIONS – Normal weight – Good health

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  5. I am immensely grateful that this post underlined that gastric sleeve surgery is beneficial for those who suffer from obesity. I never knew that the surgery was designed and intended to help those suffering from diabetes to control their diet. I will definitely ask more about the procedure for my friend, who is borderline obese.

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