What Are the Risks of Gastric Bypass Surgery?

Dr. Christopher McGowan
October 10, 2022

During the 20-year period from 2000 to 2020, the rate of obesity in the United States increased from 30.5% to 41.9%; this is a higher proportion of population than any other large industrialized nation in the world. Yet even as more and more Americans attempt to lose weight through various diet and exercise programs, the success rates tend to stay low. Over the last half century, bariatric procedures like gastric bypass have helped many people make lasting changes in their weight loss journey. But even though gastric bypass has demonstrated success, it remains an option with a number of risks and potential side effects. 

Who Can Get Gastric Bypass Surgery?      

Not everyone is a good candidate for gastric bypass surgery; indeed, it is possible to be either too heavy or not heavy enough to qualify for weight loss surgery. To determine whether someone is a good candidate, most bariatric surgeons around the world use body mass index (BMI). BMI is derived by comparing a person’s height and weight, and it is used as a rule of thumb in categorizing a person’s body weight; BMI of 18-24 is considered normal, 25-29 is overweight, and anything over 30 is considered obese.  

Body mass index is more of a predictive tool than a precise indicator of body fat content, but it does help bariatric surgeons figure out who would benefit most from the surgery. According to the American Society for Metabolic and Bariatric Surgery (ASMBS), the basic qualifications for surgery include: 

  • Having a BMI of greater than 40 or being more than 100 pounds of excess body weight
  • Having a BMI of greater than 35 or being diagnosed with an obesity-related condition (such as type 2 diabetes, high blood pressure, heart disease, or sleep apnea) 
  • Having a general inability to achieve a sustained healthy weight even after having exhausted other weight loss efforts

The ASMBS also recommends that the surgery be performed by a board-certified surgeon at a facility that has a multidisciplinary support team. Even though surgeries like gastric bypass are known to help people lose weight, the surgery alone is typically not enough to bring about long-term weight loss success. Having access to follow-up interactions from dietitians, mental health professionals, and exercise specialists often makes a huge difference in helping patients lose weight and keep it off. 

How Does Gastric Bypass Surgery Work?

The most common type of gastric bypass surgery is called Roux-en-Y gastric bypass; this is considered a minimally invasive procedure because it is performed laparoscopically and only requires small incisions. The two main goals of the surgery are to limit the total amount of food that can be eaten in one sitting and to reduce the absorption rate of nutrients from food in the small intestine. The patient feels full more quickly after eating and fewer calories are actually metabolized; over time, the resulting calorie deficit will lead to weight loss. 

The first part of the surgery involves bisecting the stomach into a small gastric pouch and a larger section that mostly sits dormant. The small pouch is then connected to the part of the small intestine known as the jejunum. Normally food would collect in the stomach and begin being broken down by stomach acid and peristalsis, but in gastric bypass this whole process is essentially delayed. Only a small amount of food is able to sit in the stomach, and this quickly triggers the release of hormones responsible for creating a sense of fullness and satiety.  

At the bottom of the now closed-off stomach remnant, the duodenum remains; the duodenum is the first part of the small intestine where stomach acid and digestive juices from the liver and pancreas normally empty into the small intestine in the digestive process. In gastric bypass, the remnant of the stomach, duodenum, and a section of intestine are then reattached to the small intestine further down the line. Because the digestive juices are introduced later in the digestive process, a significant amount of the intestinal absorption of nutrients (and thus calories) is avoided. 

What Are the Risks of Gastric Bypass Surgery?

Even if a patient is considered a good candidate, it’s important to consider the potential complications and risks of bariatric surgery. Though gastric bypass is a minimally invasive procedure, it still has inherent risks like any other kind of surgery that involves incisions; it is relatively common, for instance, to experience bleeding and minor infection directly after surgery. There are also, however, a series of potential minor or serious complications over the short and long term: 

Short term (post-op)

  • bleeding
  • infection
  • complications due to anesthesia 
  • nausea and vomiting 
  • dilation of the esophagus 
  • stomach or bowel obstruction 
  • acid reflux 
  • blood clots
  • ulcers
  • hernia

Long term 

  • Malnutrition: The nature of Roux-en-Y gastric bypass includes an intentional reduction of nutrient absorption, but this can potentially lead to malnutrition and a deficiency of certain important vitamins and minerals. To counteract this, some patients may need supplements to get sufficient amounts of nutrients like iron, calcium, and vitamin B12.   
  • Dumping syndrome: Because the stomach is so much smaller after gastric bypass, the food sometimes doesn’t get fully digested before being “dumped” into the small intestine; this is called dumping syndrome. Dumping syndrome involves problems with the hormones that control digestion and can cause a wide variety of gastrointestinal symptoms. Treatment for dumping syndrome primarily involves changes to diet and eating habits
  • Stomal stenosis: After the gastric bypass surgery is complete, the new connection point between the stomach pouch and small intestine can sometimes become tighter or narrower. This tightening is called stomal stenosis and can cause nausea, vomiting, and abdominal pain. 
  • Anastomotic Leaking: Even long after the surgery, the sutures or staples that close off the stomach can loosen and leak stomach acid, digestive enzymes, and bacteria into the abdominal cavity. This can cause inflammation of the inner wall of the abdomen (peritonitis) as well as infection or a severe abscess. 

Alternatives to Gastric Bypass

Any kind of weight loss surgery carries inherent risks, particularly for those who have other obesity-related health problems. Gastric bypass surgery has been called the “gold standard” of bariatric surgery, but in recent years new approaches have emerged that give patients new and safer options. One example is an endobariatric procedure called endoscopic sleeve gastroplasty (ESG). While it similarly aims to reduce stomach volume in order to promote a calorie deficit, it doesn’t require incisions; among other benefits, having no incisions means fewer risks and a much shorter recovery time. 

At True You Weight Loss, we know how difficult a weight loss journey can be, especially because traditional methods like diet and exercise are not effective for most people. ESG is just one of several non-surgical weight loss solutions that can start you on a new journey of long-term success. If you would like to learn more about ESG or gastric bypass revisions or any of our other state-of-the-art weight loss solutions, please contact us today to request a consultation. Our highly qualified and compassionate team is eager to help you find the freedom you’ve been waiting for.

Dr. Christopher McGowan
Dr. Christopher McGowan

Dr. Christopher McGowan, MD, a leader in endobariatrics, specializes in non-surgical obesity treatments and is triple-board-certified in Internal Medicine, Gastroenterology, and Obesity Medicine. Renowned for pioneering endoscopic sleeve gastroplasty (ESG) with over 2,000 procedures, his global influence and research contributions define him as a top expert.

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