Bariatric Surgery

Bariatric surgery procedures include gastric bypass, sleeve gastrectomy, gastric band and duodenal switch. These operations have proven results in treating class III obesity. They also help normalize your metabolism, including blood sugar, blood pressure and cholesterol.


What is bariatric surgery?

Bariatric surgery, also called weight loss surgery, is a category of surgical operations intended to help people with obesity lose weight. Healthcare providers may recommend bariatric surgery if other weight loss methods have failed and if obesity appears to pose a greater risk to your health than surgery.

Bariatric surgery procedures work by modifying your digestive system — usually your stomach, and sometimes also your small intestine — to regulate how many calories you can consume and absorb. They can also reduce the hunger signals that travel from your digestive system to your brain.

These procedures can help treat and prevent many metabolic diseases related to obesity, including diabetes and fatty liver disease. But weight loss surgery isn't an easy “quick fix”. It requires preparation beforehand and long-term lifestyle changes afterward to be successful.


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Why is bariatric surgery done?

Bariatric surgery is the most successful long-term treatment for class III obesity. According to the National Institutes of Health (NIH), it is nearly impossible for people with class III obesity to sustain weight loss through diet and exercise alone. Once your body has registered your higher weight as “normal,” it continues to try to return to that weight. Bariatric surgery works by changing how your body manages what you eat, allowing healthy diet and lifestyle changes to be effective for sustained weight loss and health.

What kinds of conditions can bariatric surgery treat?

Obesity is associated with many chronic diseases, many of which can be life-threatening. These conditions and risk factors greatly improve after surgery and weight loss. If you're a candidate for bariatric surgery, you may already have or be at risk of developing any of these diseases, including:

  • High cholesterol. Hyperlipidemia (high cholesterol) means your blood has too many lipids (fats) in it. These can add up and lead to blockages in your blood vessels. This is why high cholesterol can put you at risk for a stroke or heart attack.
  • High blood pressure. Hypertension (high blood pressure) means the force of blood flowing through your blood vessels is too high. This wears down the walls of your blood vessels and puts you at greater risk of heart attack and stroke.
  • High blood sugar. Hyperglycemia (high blood sugar) is highly linked to insulin resistance and is considered a precursor to diabetes. Left untreated, it can damage your nerves, blood vessels, tissues and organs, increasing your risk of many diseases.
  • Type 2 diabetes. Excess fat storage can lead to insulin resistance, which can lead to adult-onset diabetes (type 2). The risk of developing type 2 diabetes increases by 20% for each 1 point increase on the BMI (body mass index) scale.
  • Heart disease. Obesity can lead to impaired cardiac function and congestive heart failure. It can also cause plaque to build up inside your arteries and increases your risk of heart attack and stroke.
  • Kidney disease. Metabolic syndromes associated with obesity, including high blood pressure, insulin resistance and congestive heart failure, are major contributors to chronic kidney disease and kidney failure.
  • Obstructive sleep apnea. People with untreated sleep apnea stop breathing repeatedly during their sleep when their upper respiratory tract becomes blocked. These episodes reduce oxygen flow to the vital organs and particularly endanger the heart.
  • Osteoarthritis. Having excess weight puts extra pressure on joints like your knees. This makes it more likely that you'll develop osteoarthritis, a degenerative joint disease, or make it worse if you already have it.
  • Non-alcohol related fatty liver disease (NAFLD). NAFLD occurs when your body begins depositing excess fat in your liver. It can lead to non-alcohol related steatohepatitis (NASH), chronic inflammation that can do long-term damage to your liver.
  • Cancer. While the connection isn't entirely understood, obesity is correlated with an increased risk of acquiring more than a dozen types of cancer. It also increases your risk of death from cancer by more than 50%.


Procedure Details

What qualifies you for bariatric surgery?

Bariatric surgery requirements begin with establishing a diagnosis of class III obesity. That means that you either:

  • Have a BMI of 40 or higher. The Body Mass Index (BMI) is a way of estimating how much body fat you have based on your height-to-weight ratio. A score of 40 or higher is associated with a high risk of related diseases. It usually equates to about 100 lbs. overweight.
  • Have a BMI of at least 35 and at least one related health problem. A BMI of 35 without a related health problem is considered class II obesity.

The criteria are slightly higher for adolescents. An adolescent may be a candidate if they have:

  • BMI of at least 40 and an obesity-related medical condition.
  • BMI of at least 35 and a severe obesity-related medical condition.

While BMI is easily measured, you may have to take some medical tests to diagnose your obesity-related health conditions.

Common myths about bariatric surgery

  • That surgery is a last resort. Bariatric surgery is the most effective long-term treatment for class III obesity. When studied scientifically, diet and exercise — alone or in combination with medications — are much less effective over the long term.
  • That surgery is the “easy way out.” Bariatric surgery can be thought of as a tool that allows a healthy diet and lifestyle to lead to sustained weight loss. Often, patients have made these changes before without long-term success. Surgery allows those changes to be effective.


What’s involved in preparation for bariatric surgery?

Before scheduling your bariatric surgery, your healthcare provider will want to ensure that you’re physically and mentally fit for the surgery. You’ll meet with a team of specialists who will counsel you about the risks and benefits while evaluating your physical and mental health.

You may need to pass medical screening tests to make sure the surgery is safe for you. If you use tobacco, drugs or excessive alcohol, you’ll be required to quit before qualifying for surgery. Your healthcare team can help you with this.

Your surgeon may also ask you to follow a pre-bariatric surgery diet for a few weeks to prepare for your operation. This is to reduce the fat inside your abdomen, where the operation will take place, making the operation safer and reducing the risk of complications. Your surgeon will give you specific guidelines to follow.

How is weight loss surgery performed?

Weight loss surgery is usually performed through minimally invasive methods (laparoscopic surgery). That means small incisions, faster healing and less pain and scarring than you would have with traditional open surgery. Very rarely, some patients are better treated with open surgery due to their specific conditions.

What are the different types of bariatric surgery?

Gastric sleeve

The gastric sleeve, also called sleeve gastrectomy, is the most commonly performed bariatric surgery in the U.S. This may be because it’s a relatively simple procedure that's safe to perform on most people with little risk of complications. The gastrectomy simply removes a large portion of your stomach — about 80% — leaving behind a small, tubular portion, like a sleeve. This naturally reduces the amount of food you can consume in one sitting and makes you feel fuller faster. But it also reduces the hunger hormones that are normally produced in your stomach. This helps to stabilize your metabolism, decreasing your appetite and regulating your blood sugar.

Gastric bypass

The gastric bypass is also known as the “Roux-en-Y," which is a French term meaning “in the form of the letter Y.” With this procedure, your small intestine will end up in that form. First, surgeons create a small pouch at the top of your stomach, separating it from the lower portion with surgical staples. Then they divide your small intestine and bring the new segment up to connect to the stomach pouch. Food will now flow through the new, smaller stomach and lower segment of your small intestine, bypassing the rest. This restricts how much your stomach can hold and also how much nutrition your small intestine can absorb. Restricting the small intestine makes this method more effective than gastric restriction alone.

Biliopancreatic Diversion with Duodenal Switch (BPD-DS)

This is the original version of the duodenal switch, an operation that combines a sleeve gastrectomy with an intestinal bypass. (It sometimes goes by a shorter name: Gastric Reduction Duodenal Switch). It’s similar to the Roux-en-Y gastric bypass but more extreme. This operation bypasses most of your small intestine — about 75%. This significantly reduces the hunger hormones produced in your small intestine as well as in your stomach. It also significantly restricts how much nutrition your small intestine can absorb. This is what makes the duodenal switch the most effective surgery for weight loss and for improving metabolic syndromes like diabetes. But it can also make it hard for your body to absorb enough nutrients to stay healthy.

Stomach Intestinal Pylorus Sparing Surgery (SIPS)

This newer procedure is a modified version of the original duodenal switch, intended to reduce complications. It also goes by the names Loop Duodenal Switch or SADI-s. Early results are still being studied, but so far it appears promising that this version may eventually replace the original duodenal switch. Like the original, it begins with a sleeve gastrectomy, then divides the first part of the small intestine just after the stomach (the duodenum). This time, the small intestine is reattached as a loop, which requires just one surgical connection (anastomosis) instead of two. It also means that less of the small intestine is bypassed, allowing for a little more absorption of nutrients.

What kind of postoperative care will I have after weight loss surgery?

During the first year after your surgery, your healthcare provider will see you regularly for follow-up visits and testing. They will take metabolic blood tests to monitor how your health is improving and screen for any nutritional deficiencies. After the first year, if you're in good health and have lost a lot of weight, you may want to discuss body contouring options with your healthcare provider. Body contouring can help remove excess skin folds and tighten loose tissues.

How much weight do you lose with bariatric surgery?

Most people — about 90% — lose about 50% of their excess weight after bariatric surgery, and keep it off. Different procedures have slightly different results. The average weight loss after gastric bypass is about 70% of excess body weight. After a duodenal switch, it’s about 80%. Weight loss after sleeve gastrectomy ranges between 30% and 80%. These results are measured after a period of 18 to 24 months.

Risks / Benefits

What are the risks of bariatric surgery?

When weighing the pros and cons of bariatric surgery, it’s important to consider the risks of the operation itself as well as the possible side effects that may occur afterward.

Surgical complications

All surgeries involve certain risks. Longer and more complex operations may involve more. Risks include:

Surgery side effects

Surgeries that modify your digestive system can cause certain digestive complications. These are sometimes called post-gastrectomy syndromes. Possible complications include:

  • Dumping syndrome. This is a collection of symptoms that can occur when your stomach dumps food too fast into your small intestine. Up to 50% of people who have bariatric surgery may have some symptoms of dumping syndrome afterward. Symptoms can include nausea, diarrhea, abdominal cramping and hypoglycemia. They usually fade with time. Your healthcare team will give you dietary guidelines to help prevent or reduce dumping syndrome while you recover.
  • Malabsorption and malnutrition. Many bariatric surgery procedures intentionally induce malabsorption in your small intestine to reduce the calories you absorb. But malabsorption can lead to loose stools. It can also lead to nutritional deficiencies if you aren’t careful. Your healthcare provider will prescribe nutritional supplements to help prevent this.
  • Bile reflux. Surgery that affects the pyloric valve, the opening between your stomach and your small intestine, can cause it to malfunction. If the pyloric valve doesn’t close properly, one possible result is bile reflux. That means the bile that your gallbladder sends to your small intestine to help digest food can backwash into your stomach. Bile reflux can erode your stomach lining, leading to gastritis and stomach ulcers.
  • Gallstones. Rapid weight loss sends a large load of cholesterol to your liver to process. When your liver sends bile to your gallbladder, it carries extra cholesterol with it. This extra cholesterol can build up in your gallbladder, forming cholesterol gallstones. Gallstones don’t always cause problems, but they can be dangerous if they travel and get stuck in your bile ducts. Your healthcare provider may give you a prescription medication to prevent gallstones after surgery.

What are the advantages of bariatric surgery?

  • Significant, sustained weight loss. Surgery is the only treatment that has been proven effective for class III obesity over the long term.
  • Reduced hunger hormones and improved metabolism. Surgery is the only obesity treatment that rewires your body’s metabolic programming after obesity to prevent weight regain.
  • Cholesterol and blood sugar management. Weight loss surgery often causes remission of diabetes symptoms and allows people with various metabolic syndromes to discontinue medications.
  • A longer, healthier life. In addition to reducing diseases and discomforts related to obesity, weight loss surgery can actually extend your life. Large scientific studies have shown that bariatric surgery reduces the risks of death from any cause by over 40%.

Recovery and Outlook

How long does it take to recover from bariatric surgery?

You’ll likely spend a few days recovering in the hospital, then a few weeks recovering at home before you feel ready to go back to work. You may need to avoid strenuous activity for up to six weeks, and it may take up to 12 weeks to resume a normal diet.

What is the success rate of bariatric surgery?

Weight loss surgery is considered successful if you lose 50% of your excess weight and keep it off. By this standard, the success rate is 90%. Many people experience steady weight loss for the first two years, then stall or regain some weight after that. Usually, the weight regained is less than 25%.

A note from Cleveland Clinic

Bariatric surgery offers a much-needed, long-term solution to a difficult, progressive disease. Obesity is very hard to beat, and without intervention, it has heavy effects on your health, quality of life and lifespan. Bariatric surgery can change the biological factors that make it so hard for people with obesity to lose weight and keep it off. While surgery can have its own risks and complications, in most cases these are much lower than the risks and complications that come with obesity and its related diseases.

Medically Reviewed

Last reviewed on 06/09/2022.

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