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Bariatric Surgery for Weight Loss

  • A surgery that alters the stomach's anatomy to reduce the amount of food eaten and digested
  • For people with a body mass index (BMI) of 40 or higher or BMI of 35 but have health problems
  • For the severely obese, bariatric surgery is an effective treatment for long-term weight loss
  • Involves bariatric & minimally invasive surgery, surgery

Bariatric Surgery for Weight Loss


Bariatric surgery can help people lose weight and live healthy, active lives. There are several types of bariatric surgery procedures, but all work by changing the stomach to limit the amount of food you can eat at one time, reducing your appetite, and reducing the ability of the body to digest the food consumed. It may be worth considering bariatric surgery if you are obese and have tried other strategies but haven’t been able to take off enough weight to reduce your health risks.

It may be helpful to know that bariatric surgery also can greatly improve and sometimes reverse such obesity-related conditions as diabetes, high cholesterol, high blood pressure, sleep apnea, and chronic pain, especially in the hips and knees.

“Obesity is a chronic disease, and research has demonstrated that bariatric surgery is the most effective tool for inducing and maintaining long-term weight loss,” says Yale Medicine bariatric surgeon Randal Zhou, MD. “An astonishingly low percentage of people who are eligible—and can greatly benefit—receive this surgery.”  

What is bariatric surgery?

Bariatric surgery is the umbrella term for a variety of procedures that help with weight loss. These surgeries work mainly by changing the anatomy and size of the stomach to limit the amount of food you take in, and, in some cases, by altering your digestion process to improve fat metabolism. Some procedures impact the production of intestinal hormones, affecting appetite.

It’s important to understand that bariatric surgery itself is only part of the solution. To succeed at weight loss, you will also need to focus on developing healthy lifestyle habits. That said, bariatric surgery can make it easier for you to achieve a healthier weight and change some of the habits that contributed to the initial weight gain.

For severely obese people, the National Institutes of Health (NIH) recognizes bariatric surgery as the only effective treatment for maintaining long-term weight loss for people who have had no success with diet, exercise and other common weight-loss strategies.

What types of bariatric surgery are there?

There are several types of bariatric surgery. If you are considering a bariatric procedure, it’s important to talk to your doctor about the pros and cons of each one, and what might be best for your particular situation. Here are three different types of bariatric procedures, all offered by Yale Medicine doctors.

Endoscopic intragastric balloon. This nonsurgical approach involves inserting a balloon that fills up about half of the stomach. The balloon increases the feeling of fullness after eating, limiting the amount of food that you want to consume. It will be removed about six months later.

Roux-en-Y gastric bypass. This procedure uses staples at the top of the stomach to create a pouch about the size of an egg. This pouch gets attached to a surgically created Y-shaped section of the small intestine, so that the food bypasses the lower stomach, the duodenum (the first segment of the small intestine), and the first portion of the jejunum (the second segment of the small intestine). This not only reduces the amount of calories and nutrients the body can absorb, it can also bring about helpful changes in the gut hormones that reduce hunger.

Sleeve Gastrectomy. This procedure removes about 80 percent of the stomach and staples together the remaining portions to create a thin, vertical banana-sized sleeve. This sleeve holds less food and, therefore, you are satisfied after eating less. This method also alters digestive hormones, reducing hunger. 

Though it is not optimal for every patient, bariatric surgery can often be performed using a minimally invasive laparoscopic approach. This involves making several small cuts to the abdomen, instead of one large one. The benefits of this approach include less pain and scarring, and a speedier recovery.

Who is a candidate for bariatric surgery?

There are some clear guidelines covering who is a candidate for bariatric surgery. These include the requirement that patients be morbidly obese, with a body mass index (BMI) of 40 or higher. Or, they must have a BMI of 35 to 39 along with one or more medical conditions, such as diabetes, hypertension or sleep apnea. 

BMI is an established measure of obesity that divides your weight (in kilograms) by your height (in meters squared). You can use an online calculator to determine your own BMI.

So, to qualify for bariatric surgery as an adult, you must meet one of the following criteria:

  • A BMI of 40 or higher
  • A BMI of 35 or higher, coupled with an obesity-related health problem, such as sleep apnea, hypertension, or type 2 diabetes  

Teenagers can have bariatric surgery if they have reached their adult height, are past puberty and meet one of the qualifications listed above.

You may not be a candidate for bariatric surgery if you have a drug or alcohol abuse problem, a severe psychiatric disorder or an obesity-causing disorder that reversed without surgery.

How do I prepare for bariatric surgery?

Your surgeon will want you to see other specialists, including a dietician and a counselor, and usually a psychologist or psychiatrist. All of these practitioners provide valuable support in helping you prepare to change your eating habits after surgery, cope with body image changes, and make sure you are physically and psychologically prepared for a life-changing experience. The counselor also will help address any anxiety you may have about the surgery.

What is recovery like after bariatric surgery?

Your recovery will vary depending on the type of bariatric surgery you have. You will likely spend some time limited to a liquid diet and gradually move on to solid foods over a period of weeks. It will be important to chew your food thoroughly and eat small meals.

Does bariatric surgery work for everyone?

The amount of weight you lose will depend on the surgery, your commitment to lifestyle changes and other factors. Studies have found that more than 90 percent of bariatric patients are able to maintain long-term weight loss of 50 percent or more of their excess body weight, according to the American Society for Metabolic and Bariatric Surgery. In many cases, patients can improve their chances for success by following the advice of their surgeon and support team about how to make appropriate lifestyle changes.

What are the lifestyle changes I will need to make after bariatric surgery?

Patients who have bariatric surgery should expect to make a lifelong commitment to their weight-loss goals. Bariatric surgery makes drastic changes to the digestive system. You will need to decrease the amount of food you eat, eat more protein-rich foods, and supplement your diet with vitamins and minerals.

How is Yale Medicine unique in its approach to bariatric surgery?

Yale Medicine Bariatric & Minimally Invasive Surgery is an accredited Center for Metabolic and Bariatric Surgery through both the American Society of Metabolic and Bariatric Surgery and the American College of Surgeons. Our bariatric program was the first in Connecticut to offer minimally invasive (laparoscopic) bariatric surgical techniques, including Roux-en-Y gastric bypass, laparoscopic sleeve gastrectomy, and revisional (redo) bariatric surgery.

Our dedicated team includes world-class surgeons and experts in medicine, nursing, nutrition and psychology. They help navigate patients through all stages of weight loss and provide care in a compassionate, nonjudgmental environment for people struggling with morbid and extreme obesity.

“In addition to the wide breadth of expertise, our Yale team will treat you like family,” says Dr. Zhou. “We will listen to your goals and formulize the best treatment plan for you. We understand undergoing surgery is an anxiety-provoking process. We will support you before, during, and long after surgery.”