Amanda Singer was 17 the first time someone snaked a tube up her nose, down the back of her throat and into her stomach—funneling a nutritional supplement into her body. Singer needed the feeding tube because of anorexia bulimia. That first time, she was nervous and extremely uncomfortable but eventually she learned a few strategies to make the process easier. For example, she learned that if she drank water through a straw while the tube was being put in, the swallowing would help ease the tube down her throat. She also discovered that if she sat or lay down in a certain position, the tube went down more comfortably.

“It was never enjoyable but it got easier,” she says, “It was pretty uncomfortable, I wouldn’t say painful, but it was not pleasant by any means.”

Singer is one of thousands of people across the U.S. who receive their daily sustenance via tube-feeding because they cannot or will not swallow. In hospitals or nursing homes many patients have the tubes left in for weeks at a time. People treated at home sometimes insert and remove the tube themselves, perhaps daily.

“There are many thousands of people being fed this way in the United States on any given day,” says David Seres, director of medical nutrition at Columbia University Medical Center. Typically, if a person has to receive artificial nutrition longer than a month (pdf), it is recommended they instead have a tube inserted directly into the stomach or intestinal tract, but Seres says that in practice patients often use the nasal tube longer than the recommended time.

In recent months tube feeding has been thrust into the limelight because it is being used involuntarily on inmates on hunger strike in the U.S. prison at Guantánamo Bay in Cuba. When a person struggles against the tube, the discomfort increases and it is harder to get the tube where you want it to go, Seres says. That struggle can lead to physical complications including injuries to the nose and throat, nose bleeding and minor cuts. The psychological impacts, however, have not been widely studied.

Beyond force-feedings, people often associate tube-feeding with individuals in comas. “There’s a misconception out there—force-feeding is not just for people in vegetative states or situations like Guantánamo,” Seres says. Individuals with a variety of maladies including stroke, or other neurological disorders, cancer of the throat or a loss of appetite due to chronic illnesses like liver disease may receive nutrition via a tube placed through the nose leading either to the stomach or farther down in the digestive track. In Seres’s hospital there are 60 people receiving tube-feedings on any given day, and approximately 75 percent receive them through nasogastric feeding tubes like Singer’s. “We believe that the products that we use to feed people provide adequate and balanced nourishment,” Seres says.

The mixture entering into the body during tube-feeding may be Ensure—the can sold at supermarkets that looks vaguely like a milkshake. If it is not Ensure, it is often a similar concoction—a liquid slurry of protein derived from milk or soy, sugars, starches, oils, vitamins and minerals.

This week a group of physicians and lawyers spoke out against the force-feeding of inmates at the Guantánamo Bay prison. In an essay published in The New England Journal of Medicine they argue that this tube-feeding violates medical ethics. “Hunger striking is a peaceful political activity to protest terms of detention or prison conditions; it is not a medical condition, and the fact that hunger strikers have medical problems that need attention and can worsen does not make hunger striking itself a medical problem,” they wrote.

As of Tuesday, 106 of the 166 detainees at the detention center at Guantánamo Bay were engaged in a hunger strike, according to the Department of Defense (DoD). Forty-five detainees have missed nine consecutive meals and their doctors decided they needed to be fit with feeding tubes. During Ramadan, which started this week, the DoD intends to honor religious requirements against eating during daylight hours, including for detainees on hunger strike, says Lt. Col. Todd Breasseale, a Pentagon spokesman.

Before being force-fed, detainees typically receive a topical anesthetic before the lubricated three-millimeter tube is inserted, and then they are generally fed about two cans of Ensure, Breasseale told Scientific American in an e-mail.