How long can we survive without food? A: 382 days
A case report published in March 1973 in Postgraduate Medical Journal described how the patient Angus Barbieri spent 382 days without eating. His self-experiment ran between June 1965 and July 1966.
When he checked himself in at Maryfield Hospital in Dundee, Scotland, he was grossly obese, weighing around 456 lbs (~207kgs) .
382 days later marked the end of his fast. He was around 180 lbs (~82kgs). His weight remained stable at ~196 lbs (~89kgs) in the follow-up period of 5 years after the fast ended.
Throughout the experiment he consumed water, tea, coffee, and some supplements. He was under the supervision of researchers from the University of Dundee. They collected blood and urine samples, making observations on his progression.
Not surprisingly, fecal evacuations were very infrequent in the late period of the fast, with times between stools averaging from 37–48 days. I thought you may wanna know that.
Barbieri lost 276 lbs (~125kgs) during his 382-day fast. From what I know, this is the longest medically recorded fast in the science literature. Many other long-term fasting experiments have been conducted in the 1960s — their main focus was to treat obesity. Today they are considered unethical. Some of them were successful, some of them were not, while a few of them were fatal (mostly due to complications — on the background of pre-enrollment ill health of the patient).
In the case of Angus Barbieri, researchers tracked blood glucose levels, calcium levels, urea, uric acid, creatinine, magnesium and several other biomarkers. For geeks interested in a detailed interpretation of this case report, you can read my full scoop here.
This voluntary experiment goes to show the physiologic potential we have as human beings and it should dispel some myths about the imminent starvation that many of us fear when we don’t consume food every couple of hours.