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The man who ate charcoal and glass in the name of science

If you are what you eat, then Frederick Hoelzel is about as close as it gets to a human billy goat grazing the gutters of a city street.

As a teenager in the early 1900s, Hoelzel suffered from stomachaches. He wanted to experiment with not eating food, which he thought was making him sick, but worried about the effects of hunger. So he set out on a series of self-experiments to rid himself of his stomachaches by eating calorie-free substitutes.

Those substitutes included things the average person wouldn’t dare put in his mouth–think charcoal, sand, chalk, straw, sponge, hair, wool, glass balls and feathers. However, nothing seemed to satisfy Hoelzel like surgical cotton.

In the 1920s, Hoelzel was finally able to apply his peculiar interest in digestion to the scientific community when University of Chicago Physiologist Anton Julius Carlson took him under his wing. Carlson turned Hoelzel’s self-experimentations into bona fide research. For example, they conducted an experiment to determine whether long-term fasting could rid one of the feeling of hunger. They also studied how long it took certain objects to move through Hoelzel’s digestive system; they discovered that gold pellets took the longest (22 days) and knotted twine blasted through his system the fastest (90 minutes).

For all of Hoelzel’s digestive sacrifices, he merely gained the title of Assistant in Physiology. Despite this, he was able to pave the way for some serious scientific studies–like being one of the first researchers to suggest overeating could shorten your life. And remember Hoelzel’s favorite meal of surgical cotton? It inspired him to make cellulose flour. And though not widely accepted during his lifetime, cellulose is a go-to additive in diet foods today.

Sacrificed is a Fusion original series in which we share the stories of scientists so passionate about their research, they use themselves as human guinea pigs, subjecting their bodies to dangerous conditions and diseases in a valiant (though sometimes misguided) search for the truth.

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