Obviously humans need food. People who try to survive on just light and air die.
And while there are stories like Barbieri's that make fasting almost sound safe and transformative, those who worry that fasting proponents sound like dangerous snake-oil salesmen can find stories to vindicate their case, too. Take the story of Linda Hazzard.
Hazzard was a practitioner of alternative medicine in Washington state in the early 1900s. She branded herself a "fasting specialist" and wrote articles and books with titles such as "Fasting for the Cure of Disease." She even started her own fasting clinic, the Institute of Natural Therapeutics in Olalla, Washington.
Many considered her a serial killer. About 50 people reportedly died in Hazzard's care, though she was convicted of only one murder. "Tales are told of her Sanitarium in Olalla on the Kitsap Peninsula, where starving patients stumbled like human skeletons into town, begging for food or help," according to a post on the Washington Secretary of State's office blog. During their treatments, "patients consumed only small servings of vegetable broth, their systems 'flushed' with daily enemas and vigorous massages that nurses said sometimes sounded more like beatings," according to Smithsonian Magazine. Before their deaths, many of those patients willed their estates and inheritances to the "doctor."
Hazzard was eventually found out after the case of Claire and Dora Williamson. The sisters had enrolled at the center for treatment, but after some time, one of them sent a disturbing message that persuaded their childhood nurse to travel from Australia to Washington to find them. When the nurse arrived, Claire was dead and Dora weighed about 50 pounds, and Hazzard had actually been appointed her guardian. The sisters' uncle eventually paid Hazzard a thousand dollars to get Dora away from the property. That led to other revelations and, eventually, a murder trial. Hazzard was convicted of murdering Claire Williamson.
But for reasons that remain unclear, Hazzard was pardoned after serving two years. She traveled to New Zealand before returning to Washington to build a new sanitarium. Eventually, after falling ill, she tried to cure herself in the way that she knew and seemed to believe in, by fasting. That last fast killed her.
Hazzard, of course, wasn't just a quack. She appeared to have had malicious intent.
Under a doctor's supervision, most people can handle a fast of a certain duration, especially if they take vitamin supplements. But researchers have found that after about six weeks people start to enter a danger zone, according to Frank Greenway, chief medical officer at Pennington Biomedical Research Center at LSU. By seven weeks, electrocardiograms start to show heart trouble, and by eight weeks people are at risk of sudden death, Greenway says. Skinny people might enter that danger zone sooner.
Even diets that provide food but not adequate nutrition have killed people in this way. In the late 1970s, Greenway says that an osteopath named Robert Linn wrote a book called "The Last Chance Diet," which promoted a low-calorie, high-protein solution for weight loss. But the nutritional drink Linn sold was made with a low-quality protein, which didn't provide what people need to live. A number of people on this diet died, their hearts showing signs of starvation.
Those risks are real, but experts such as Greenway and Mattson do agree that most people, especially those with some weight to lose, are fine on longer water fasts lasting several weeks, as long as they are medically supervised and in reasonable health to begin with (certain health conditions might be exacerbated by fasting).
One of the biggest myths about fasting is that it's dangerous, says Alan Goldhamer, an osteopathic physician and chiropractor in California and the founder of TrueNorth Health Center, where 15,000 patients have undergone periods of water fasting over the past 32 years.
Barbieri completed his 382-day fast after all, and his isn't the only fast longer than 100, 200, or 300 days. In 1964, researchers published a study noting that "prolonged starvation" could be an effective treatment for severe obesity, with at least one patient fasting for 117 days. For medical reasons, several others have exceeded the 200-day fasting mark, though there has been at least one death during the refeeding period for one of those patients. (Suddenly introducing nutrients to a malnourished person can be deadly.) At least one person has even gone longer without food than Barbieri; a man named Dennis Galer Goodwin lasted 385 days on a hunger strike to assert his innocence of a rape charge before he was force-fed through a tube. But those are extreme examples. Fasts longer than a few weeks are rare.
Still, Goldhamer says patients at TrueNorth have medical supervision throughout their fasts. Clinic staff members keep an eye on people and ensure that they'll be able to give them electrolytes or broth if they become faint or have a medical emergency.
Many people are comfortable enough with fasting that they embark on long fasts on their own. Chris Guida, one such self-experimenter I reached out to through Reddit, described how he decided to start a three-week fast.
Fasting was just one part of a longer effort to improve Guida's health that started in 2013 and involved various diets and exercise programs such as CrossFit, he tells Business Insider. At the time, he was 24 and having back pain. He'd lost the ability to hear certain treble frequencies in one ear. So he decided he wanted to try to conduct a self-optimization project, turning himself into a "science experiment." He tried the paleo diet, eliminated caffeine, and stopped sitting all day (he'd been working as an app developer).
Eventually he came to fasting, which seemed like the "logical" conclusion of his efforts.
"I found tons of helpful resources online that convinced me I shouldn't have any problems, and once I found r/fasting, I knew I could turn to that community if I really needed anything," he wrote, just over one week into his own water-only fast. "It was time."
Sixteen days into his fast, Guida told Business Insider that he felt good but that, overall, he didn't have a ton of energy. He said he was cautious because his weight was already pretty low.
Goldhamer said "we tend not to want to go over 40 days unless we absolutely have to" and that certain patients with severe medical conditions can be too sick to fast. He still argues that fasting is safe, but agrees complications are more likely with longer durations. The Guinness Book of World Records stopped keeping records on periods of prolonged starvation at least in part because they didn't want anyone to die trying to exceed a record.