Written by By Carma Hassan, CNN
Surgery to eliminate excess weight or belly fat can prevent many serious diseases, including heart disease, Type 2 diabetes and heart attack, but recent research suggests that it can also prevent complications in other parts of the body.
The so-called Lap Band, gastric bypass and other bariatric surgeries are often criticized for causing significant side effects such as joint pain, anxiety and sexual dysfunction — in some cases, even death.
But in a new study published by the journal “American Journal of Gastroenterology,” researchers found that weight loss surgery was associated with a 33% decreased risk of developing severe liver disease, as well as a 36% decrease in chance of developing fatty liver disease.
Determining which patients are most likely to develop severe liver disease is complicated. According to the study authors, a person’s underlying liver disease is usually fairly invisible, making it hard to tell whether weight loss surgery will improve liver function.
Liver disease is defined as any form of liver inflammation, necrosis, scarring, or insufficiency, which can ultimately result in death, according to the Mayo Clinic.
Similar to a burn victim
“It’s important to note that (SLS) is not the same as fat burn,” says co-author and George Washington University gastroenterologist Dr. Arash Khatibi.
“They’re very similar in that there’s damage to the organ, the liver does not work the way it should and because the organs need fatty acids to function properly, the liver tends to become enlarged. At the same time, that enlargement can cause pain and dyspepsia (a symptom related to pain).
“That’s why there are other diseases associated with this process of cirrhosis that are typically caused by tobacco use, alcohol abuse and other things, rather than due to weight gain.”
In the study, the researchers looked at two groups of patients: those who underwent bariatric surgery and those who did not.
In the first group, they followed between 3,075 and 4,546 people across an average of nearly three years.
The group who had weight loss surgery underwent operations that could either selectively remove large parts of the stomach, or completely reduce the stomach from the belly — roughly a 50% reduction.
These surgeries are known to cause liver injuries, sometimes to the point of death. However, their authors say that because it is very hard to precisely measure liver damage during weight loss surgery, the study was able to take an indirect approach to determining liver injury with a weight loss surgery.
In doing so, researchers used MRI to measure damage to the liver, compared to a control group of adults who did not undergo weight loss surgery. From this measurement, researchers determined a 33% decrease in risk of severe liver disease in those who had undergone weight loss surgery.
According to the study authors, because they were able to investigate how liver injury will progress after the gastric bypass, the results were almost exact, regardless of weight loss surgery method.
This, the authors say, means that the findings are likely applicable to a much larger population than initially thought.
After Lap Band, other problems
Another key finding in the study was that the eventual impact of weight loss surgery could vary depending on the patient.
A patient who has gastric bypass surgery, or other smaller-sized gastric operations, and then later has surgery to reduce their stomach size, is likely to have a worse outcome, according to the study authors.
Their analysis found that having a hysterectomy after gastric bypass surgery could even increase the risk of liver failure.
The fact that a patient who later has gastric bypass surgery has worse liver function may be linked to the surgery’s larger size, says Khatibi.
While it is important to understand the factors that have such a huge effect on this experiment, the researchers say that the results do have some limitations.
Although the study followed thousands of people across a range of pre-existing medical conditions, no prior information was given on age, ethnicity or socioeconomic background.
The authors were also not able to determine the source of the bacterial infections that were identified in the stomach in any of the patients.
Khatibi, as well as other major medical organizations, says that evidence-based guidelines on bariatric surgery should be developed to assess the risk of adverse effects — but for now, patients should continue to discuss their options with their doctors.