On November 27, surgeons in India operated on a man admitted for abdominal pain to find and remove 15 pounds of metal foreign objects from his stomach.

Maksud Khan, 35, had been complaining of stomach pain for three months, according to The Independent, and when doctors did an endoscopy, they found hundreds of coins, 3 pounds of nails, dozens of shaving blades, shards of glass, stones, and a 6-inch piece of rusted iron shackle.

This isn't the first time someone has ingested foreign objects like Khan did. In fact, a 2012 study published in Clinical Gastroenterology and Hepatology looked at 33 patients at the Rhode Island Hospital who swallowed things like pens, batteries, knives, and razor blades.

While we don't know precisely what caused Khan's and the others' behavior, there's an explanation for why some people are compelled to do this.

According to psychiatrist Ken Yeager, Ph.D., director of The Ohio State University Wexner Medical Center's Stress Trauma and Resilience (STAR) Program, an eating disorder called Pica may be the cause.

"Pica involves eating items that are not typically thought of as food," Yeager says. "It frequently occurs with other mental health disorders like intellectual disability, Autism Spectrum Disorder, or Schizophrenia."

There is no single identified cause of Pica, but Yeager says that according to The Handbook of Clinical Child Psychology, it frequently begins in childhood and affects between 4 and 26 percent of the population.

"Frequently, these actions [of eating foreign objects] help to calm the individual," Yeager says. "There is a connection with anxiety, and many who have anxiety also suffer from depression at times."

The first line of treatment, says Yeager, is to test for mineral or nutrient deficiencies like iron or zinc. Many cases can be lessened or resolved by correcting these deficiencies if they're present. Since Pica is a form of an eating disorder, approaches like therapy are also helpful.

If someone has already ingested a lot of foreign objects, a laparotomy is usually performed, where surgeons make a large incision in a person's abdominal wall to be able to access the abdominal cavity where the objects are. And according to the Healthcare Cost and Utilization Project, Pica hospitalizations have essentially doubled in the last decade, increasing by 93 percent between 1999 and 2009.

What can you do if you suspect someone you know might be suffering from Pica? Yeager has some words of advice.

"The most important tool in communicating with anybody—mentally ill or not—is respect," he says. "Treat the other person like you would like to be treated. When someone feels respected and heard, they are more likely to be respectful and consider what the other person has to say."