A new study suggests that weight loss surgery increases a person's likelihood of committing suicide or exhibiting other self-harming behaviors. Canadian researchers found that this likelihood occurs mostly two or three years after the surgery, Health Day reported.

This is true, in particular, to those who were already suffering from some kind of mental illness or depression about five years before they went through the surgery.

"While we are clear and confident about the medical benefits of weight loss, especially through weight-loss surgery, I think we're not as attentive to the potential psychological benefits or harms of it," Dr. Amir Ghaferi, director of bariatric surgery at the Ann Arbor Veterans Administration Healthcare System in Michigan, told Health Day. Ghaferi was not involved in the study but wrote an editorial about it.

To investigate the association between bariatric surgery and self-harming behavior, the researchers studied 8,800 patients, following them for three years before the surgery and three years after the surgery. They found that after weight loss surgery, 111 of them committed a total of 158 suicide attempts that became emergency room cases.

Ninety-three percent of those who attempted suicide were struggling with a mental health disorder before the surgery, while 78 percent of them attempted suicide by overdosing on medications.

The study authors emphasized that the study only looked at emergency room cases and suggested that their results could be underestimated.

There could be several explanations for these self-harming behaviors, according to the researchers. Hormonal changes could be driving these behaviors. The patients could also be subject to more stress and anxiety after the procedure.

Additionally, bariatric surgery alters the way alcohol gets broken down in the body such that a person could get drunk faster with a lesser amount of alcohol, causing the person to throw away inhibitions against self-harming behavior more easily.

Whatever the reason, the researchers emphasized the importance of following up on patients particularly two to three years after the surgery, citing "the need for screening for suicide risk during follow-up."

"Bariatric surgery follow-up is notoriously poor," Ghaferi said. "We try to maintain at least one-year follow-up with our patients, but it's hard. Patients fall off the radar. They move, or it's the type of operation where if they're doing well or doing poorly, they're not going to come see you."

He said that offering incentives to patients might push them to keep coming back for follow-up.

The study was published in the Oct. 7 issue of the journal JAMA Surgery.