There are various weight loss surgeries available to people depending on their body mass index (BMI) and if they have certain medical conditons. There are benefits and risks to consider for each type of surgery, so it is important to discuss these with a medical professional.

Approximately 1 in 3 American adults are overweight, while more than 2 in 5 people have obesity. Obesity-related conditions such as diabetes and stroke may lead to serious complications if left untreated.

A number of existing weight loss or bariatric surgeries may help with weight loss. The American Society for Metabolic and bariatric surgery (ASMBS) estimates 256,000 people in the United States underwent a weight-loss operation in 2019.

This article lists various weight loss surgeries, their advantages, potential drawbacks, and risks.

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Surgery may also be suitable for individuals who have tried different nonsurgical methods to reduce excess weight that have not been successful.

The Centers for Disease Control and Prevention subdivide obesity into three categories:

  • Class 1: BMI of 30–less than 35
  • Class 2: BMI of 35–less than 40
  • Class 3: BMI of 40 or higher — doctors categorize Class 3 obesity as severe obesity

According to current guidelines in bariatric surgery, a person should have a BMI of 40 or higher (Class 3) to qualify for bariatric surgery.

A person with a BMI of 35–39 (Class 2) can also qualify if they have an obesity-related condition that can resolve or improve with the surgery. These include:

The ASMBS has suggested lowering the threshold for bariatric surgery for individuals with a BMI of 30–34 (Class 1). This is also based on a person’s preference, the presence of conditions such as gastroesophageal reflux disease (GERD) or type 2 diabetes, or blood sugars that are uncontrolled by medications.

Bariatric surgeries are surgical procedures that make significant changes to the digestive system. Treatment aims to treat obesity and help people lose weight.

Surgery may involve the following methods:

  • Restriction: These procedures make the stomach smaller and helps slow down digestion. By reducing the amount of food the stomach can hold, this method may help lessen a person’s food intake as it decreases calorie intake.
  • Malabsorption: This type of procedure shortens or alters the structure of the digestive tract. This causes food to bypass or bypassing portions of the tract which limits the nutrients and calories absorbed by the body.
  • Mixed (restrective and malabsoprtive): These procedures cause malabsorption and also limit food intake.
  • Reduction of hunger hormones: These are newer procedures that focus on reducing the production of the hunger hormone produced in the stomach and sent to the hypothalamus in the brain.

Bariatric surgery offers a range of benefits. A 2021 study found that it can improve metabolism and subclinical (asymptomatic) cardiac function.

A 2020 review also stated that bariatric surgery improved weight loss and diabetes outcomes compared to nonsurgical methods.

Below are different types of bariatric surgeries available to people who are suitable for weight-loss surgery. There are several benefits, drawbacks, and risks to consider for each procedure.

Gastric bypass, also called Roux-en-Y, is a mixed procedure that restricts the size of the stomach and limits food absorption.


This method involves cutting the top portion of the stomach to form a pouch the size of an egg. The surgeon also cuts the small intestine and attaches its lower part to the stomach pouch.

Following this procedure, foods will go directly into the lower portion of the intestines. Skipping a part of the digestive tract means that the body will absorb fewer calories, potentially leading to weight loss.


There are a number of benefits of this type of procedure, including:

  • rapid and long lasting weight loss
  • increase in feelings of fullness
  • rapid improvement and remission of type 2 diabetes and GERD


There are several drawbacks to this type of procedure. It:

  • is more complex than other procedures
  • requires strict diet and vitamins and nutrient supplementation for life
  • may cause dumping syndrome, or symptoms such as tiredness and nausea after a meal due to rapid gastric emptying


It is important to consider the potential risks, including:

Gastric banding is a type of restrictive procedure. It is minimally invasive, adjustable, and reversible.


Adjustable gastric bands are inflatable silicon bands that a surgeon secures at the top of the stomach. This creates a pouch above the band.

The feeling of fullness depends on the opening between the pouch and the rest of the stomach. Doctors can adjust this opening by injecting fluid through the access port underneath the skin.


Medical professionals consider this type of procedure to have the following benefits:

  • no cuts in the gastrointestinal tract
  • an outpatient procedure
  • fast recovery time
  • adjustable and removable band
  • lowest risk of complications and deficiencies


The drawbacks may include:

  • less impact on weight-related conditions such as diabetes
  • less weight loss than other procedures
  • implant stays inside the body
  • high-rate of reoperation


There is a risk of the following incidences:

  • band slippage or erosion into the stomach
  • potential damage to the stomach over time
  • additional surgery may be necessary

Sleeve gastrectomy, or “sleeve,” is a restrictive type of weight loss procedure.


The procedure involves the removal of around 80% of the stomach, leaving only a banana-shaped section that the surgeon closes with staples.

Part of the removed stomach produces most of the hunger hormone called ghrelin, which affects a person’s appetite and metabolism. It also helps with blood sugar control.


The benefits of a “sleeve” include:

  • a safe, relatively short, and straightforward procedure
  • ideal for people with high-risk medical conditions
  • performed as an initial step to other procedures


There are some downsides to this procedure, such as:

  • a non-reversible procedure
  • less impact on metabolism compared to a gastric bypass
  • can cause heartburn or worsen existing heartburn


This type of procedure does carry some risks, including:

The biliopancreatic diversion with a duodenal switch, or simply duodenal switch, is a complex surgery that creates more weight loss than a gastric bypass. It is not as common as sleeve gastrectomy and Roux en-Y gastric bypass. However, it is growing in popularity.

Doctors recommend this procedure for people with BMIs at 50 or higher.


This procedure involves removing two-thirds of the stomach to create a new stomach pouch and removing the upper part of the small intestine. The latter third of the small intestine attaches to the new stomach pouch.

The surgeon reattaches the middle third of the intestine to the end of the intestine. This allows the gastric juices and enzymes to flow to this area and digest food.

This procedure bypasses around 75% of the small intestine, significantly reducing calorie and nutrient absorption.


This procedure has the following benefits:

  • faster and more significant weight loss than gastric bypass
  • most effective for type 2 diabetes
  • targets hormone production, causing more fullness and less hunger


The downsides to this procedure are:

  • complex surgery with a long operating time
  • requires lifetime vitamin and nutrient supplementation
  • can cause reflux or worsen existing reflux


There are a number of risks to consider, including:

  • gastric leaking
  • chronic malabsorption syndrome
  • vitamin and nutrient deficiency and related conditions such as osteoporosis and anemia
  • surgical risks, such as bleeding, blood clots, hernia, infection, and death

In 2015, the Food and Drug Administration (FDA) approved balloon systems as a restrictive weight-loss strategy, such as Orbera. This is a nonsurgical and reversible outpatient procedure performed under mild sedation.


This involves placing a deflated balloon in the stomach using a thin tube (gastroscopy) passed down the throat. Once settled, the doctor inflates the balloon with saline solution.


The advantages of this type of method are:

  • there are no surgical cuts or anatomic alterations
  • the balloon is temporary and only left in for a maximum of 6 months
  • relatively safe with the use of saline solution made of salt and water


However, the balloon systems do have the following cons:

  • as it is a temporary measure, may not have long-term effects
  • cause muscle pain, headache, and nausea from the procedure
  • may result in stomach aches, feelings of indigestion, stomach ulcers, and vomiting several days after balloon placement


Experts consider this procedure to have certain risks, such as:

Since 2016, the FDA has received reports of a total of 12 deaths that occurred in patients with liquid-filled balloon systems worldwide. The FDA continues to monitor the safety and effectiveness of these devices and assess possible risk factors.

Vagal blockade or vBloc is a minimally invasive procedure implanted under laparoscopy and general anesthesia. It aims to block the hunger signals between the stomach and the brain through the vagus nerve.


The doctor places a device under the skin near the ribcage using three to five incisions.

This device delivers intermittent electrical pulses that are low energy and high frequency to the intra-abdominal vagal trunks for a predetermined number of hours each day.


This method has some positive aspects, such as:

  • it is minimally invasive, safe, and reversible
  • there are fewer complications than other weight-loss surgeries
  • noted improvements in weight loss and blood pressure


Vagal blockade may carry some drawbacks, for example:

  • malfunction and battery drainage
  • effects such as heartburn, indigestion (dyspepsia) and diffuclty swallowing (dysphagia)
  • pain at site of implantation or incision


The potential adverse effects of this method include:

  • the need to modify position of implant
  • risk of infection
  • adverse effects from the anathesia such as nausea and vomiting

Below are questions that a person may ask their doctors to know their options and what to expect before, during, and after the weight loss surgery. These include:

  • Do I qualify for bariatric surgery?
  • How does each type of surgery compare?
  • How much weight will I lose and how quickly?
  • What are the potential side effects of each procedure?
  • Is the procedure reversible?
  • Are there minimally invasive procedures available?
  • How much and what food can I eat afterwards?
  • Will insurance cover it?

Read more about Medicare here.

Following surgery, a person will experience the biggest weight loss during the first few months. After a few months, weight loss will gradually decrease.

The success rate of a procedure is measured by the percentage of excess weight a person loses.

Within the first 2 years, a person can expect to lose average proportions of:

  • 50% with a gastric band
  • 50–60% with sleeve gastrectomy
  • 60–70% with gastric bypass

However, many factors aside from the type of surgery can also affect how much weight a person can lose. These include:

  • age
  • weight before surgery
  • overall health
  • ability to exercise
  • aftercare
  • dietary guidelines

As with any weight loss program, a person may be able to maintain a moderate weight by following a balanced diet and increasing physical activity.

People who have experienced unsuccessful nonsurgical methods for weight loss can try bariatric surgery. However, they need to meet specific criteria to qualify. Currently, weight loss surgery is only for people with BMIs at 35 and above.

Each type of surgery comes with its own risks of side effects and complications. People must discuss their options with their doctors and find the most appropriate type of surgery that meets their needs.