A new study published in the journal Obesity found that people with severe obesity who underwent bariatric (weight loss) surgery were significantly less likely to die from heart disease, diabetes, or cancer, compared with people with severe obesity who didn’t have the surgery.
After a follow-up of up to 40 years post-surgery, people who underwent weight loss surgery saw their risk of premature death from any cause cut by 16 percent when compared with matched subjects who did not have bariatric surgery, says coauthor Ted D. Adams, PhD, MPH, researcher and professor at Intermountain Surgical Specialties–Digestive Health Clinical Program and in the department of nutrition and integrative physiology at the University of Utah in Salt Lake City.
“Additionally, the patients who had bariatric surgery had 29 percent, 43 percent, and 72 percent lower death rate from cardiovascular disease, cancer, and diabetes, respectively, when compared to the matched subjects who had not had bariatric surgery,” says Dr. Adams.
Bariatric Surgery Effects Go Beyond Weight Loss
Bariatric surgery surgically alters the digestive system to help people lose weight. There are three major types of surgery, with the two most common methods being sleeve gastrectomy and Roux-en-Y gastric bypass, according to Mayo Clinic. In both surgeries, surgeons seal off or remove part of the stomach, thereby limiting the amount of food a person can eat at one time and reducing the absorption of nutrients.
Typically, the stomach can hold about 3 pints of food, but after gastric bypass, the much smaller food pouch can only hold about 1 ounce.
Bariatric surgery is much safer and less invasive today than when it was first performed in the 1950s, in large part due to the introduction of laparoscopic surgery (performed with just a small incision using a camera), says Dana Portenier, MD, a weight loss surgeon at Duke Health in Durham, North Carolina, who was not involved in the research.
“We also eventually discovered that this surgery is just not shrinking the size of the stomach or how much food is absorbed. It’s also changing some of the hormones in the GI tract and this affects more things than weight, things like diabetes and metabolic syndrome,” says Dr. Portenier.
A person is considered to have metabolic syndrome when they have three of the following conditions, according to the National Heart, Lung, and Blood Institute:
- A large waistline, or abdominal obesity
- High blood pressure
- High sugar levels
- High blood triglycerides (a type of fat found in the blood that can raise LDL or “bad” cholesterol levels
- Low HDL cholesterol (sometimes called “good” cholesterol)
“When metabolic syndrome is treated, we’ve found that people live longer and do better. Based on the evidence, the indication or recommendation on who may benefit from bariatric surgery has changed. It relies less on weight or BMI and more on whether the person has metabolic syndrome. As a result, some of the restrictions around weight are being dropped lower,” Portenier says.
Only About 1 Percent of People Who Are Eligible to Get Surgery Elect to Have It
Right now, about 1 percent of the people who are eligible to get this type of surgery elect to have it. That’s between 200,000 and 250,000 people per year in the United States, says Portenier. “The number of people choosing to have surgery has grown, but not as fast as the obesity rate,” he says.
It’s estimated that 41.9 percent of adults in the United States have obesity today, according to the Centers for Disease Control and Prevention (CDC). About 20 years ago, it was estimated that about 30 percent of Americans had obesity, per the CDC.
Findings Support the Benefits of Bariatric Surgery
To investigate how bariatric surgery affects the risk of death, investigators matched 21,837 people into pairs: one person who had surgery, and one who did not. The subjects were paired for age, sex, and body mass index (BMI). Mortality rates were compared and ranked according to sex, surgery type, and age at surgery.
“I believe our findings support the benefits of bariatric surgery,” says Adams. The results should also encourage future research to try and determine what changes are happening in the body due to bariatric surgery so that new nonsurgical treatments can be developed that have the same benefits, he says.
Portenier agrees, saying, “Forty years of data — and keep in mind bariatric surgery 40 years ago was very different than it is now and had a much higher risk — shows that those who had surgery lived longer. That’s what we’re trying to do in most medical interventions: help people live longer and healthier lives.”
The surgery also dramatically reduced the risk of dying from most major diseases — heart disease, diabetes, and cancer — he adds.
People Who Had Bariatric Surgery Had a Higher Risk of Suicide
Researchers found that death from suicide was significantly greater among the bariatric surgery group compared with the nonsurgery group, mostly among those who had their surgery when they were ages 18 to 34 years old.
These findings indicate that more aggressive, pre-surgical psychological screening and post-surgery follow-up may be beneficial, according to the authors.
This finding on suicide risk is concerning and warrants attention, though it does align with previous research, says Portenier. “When we look at surveys of people who are struggling with their weight and considering bariatric surgery, we do see a higher rate of depression and other mental health conditions, and the most common medications that people report taking are antidepressants,” he says.
Insurance companies and medical guidelines now require healthcare providers perform a psychological evaluation up front before moving forward with the surgery, says Portenier. “At Duke, we have embedded psychologists here at our weight loss clinic that work hand in hand with us. We have a team approach to ensure that people can access the support they need. What this study highlights is the need to continue that long-term mental health support after surgery, too,” he says.
There can be an initial euphoria or “honeymoon” right after surgery where people’s mood can really improve for a period, but that eventually wears off and the difficulties of day-to-day life remain, which can be quite difficult for some people, says Portenier.
“There also needs to be more research about how bariatric surgery may impact the absorption of antidepressants or other medications people may be on for mood disorders. We need to make sure that a person’s depression is still being adequately managed,” he says.
Bariatric Surgery May Increase the Risk of Death From Chronic Liver Disease
The study also found evidence suggesting bariatric surgery leads to an increased risk of death from chronic liver disease.
Obesity is becoming one of the leading causes of patients needing a liver transplant in America, even surpassing alcohol misuse, says Portenier. “We know that with fatty changes in the body, that leads to fatty deposits in the liver, which can lead to permanent changes. There’s a lot of evidence that suggests that bariatric surgery helps with liver disease. But in this study, that’s not what the authors found over the course of the follow-up,” he says.
“These findings don’t really match what we’ve seen in other research. Many hepatologists [who deal with diseases of the liver] are sending patients to bariatric surgery because of the benefits it can have for the liver. It could be that in the long-term, that might not always be the case. I think the jury is still out on that,” says Portenier.
Bariatric Surgery Is Losing Its Stigma
“I think the attitudes around weight loss surgery have evolved and it’s more accepted by the general population. Part of that is that it’s much safer than when it was first introduced,” says Portenier.
But some long-standing biases and misunderstandings about people with obesity still linger. “People can see obesity as an individual failure rather than a real genetic disease process like high blood pressure or high cholesterol. But more and more people are beginning to recognize it for what it is — a disease process — and we’re slowly seeing attitudes change,” he says.
Portenier believes that more people should be choosing surgery to treat their obesity and metabolic syndrome. “I think a lot of that [reluctance to opt for surgery] has to do with the fact that we make it all about the weight in the United States, and there can be a stigma with that. In many countries, bariatric surgery is considered surgery for diabetes or for metabolic syndrome, which emphasizes that the surgery is to treat a disease, rather than just a way to drop weight,” he says.
Updated Guidelines on Who Is Eligible for Bariatric Surgery Were Released In 2022
The National Institutes of Health (NIH) released new guidelines for weight loss surgery in October 2022, the first update in 30 years. In the 1991 NIH consensus statement (PDF), bariatric surgery was limited to people with a BMI of at least 40 or a BMI of 35 or more and at least one obesity-related condition such as hypertension or heart disease.
BMI is a person’s weight in kilograms divided by the square of their height in meters. A BMI of under 18.5 is considered underweight, 18.5 to 24.9 is within the healthy range, 25 to 29.9 is within the overweight range, and 30 or higher falls within the obese range, according to the CDC.
The updated guides, developed by the American Society for Metabolic and Bariatric Surgery (ASMBS) and the International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO), now recommend metabolic and bariatric surgery for individuals with a BMI of 35 and that it be considered for people with a BMI of 30 to 34.9 and metabolic disease.
But even without metabolic disease, the guidelines state that weight loss surgery should be considered starting at BMI 30 for people who do not achieve substantial or durable weight loss or obesity disease-related improvement using nonsurgical methods. It was also recommended that obesity definitions using standard BMI thresholds be adjusted by population and that Asian individuals consider weight loss surgery beginning at BMI 27.5.
“These recent guideline changes are a good step in the right direction so that people with metabolic syndrome can get what they need,” says Portenier.
