Why would any man eat charcoal or glass? For science, of course! Frederick Hoelzel, known as the glass-eating scientist, conducted a range of bizarre experiments throughout the late 19th century, and early 20th century in which he test the limits of digestion in some very stomach-churning ways.

He first became curious about digestion when he was a teenager; spending most of his life in bed, Hoelzel was plagued by stomach ailments he mostly attributed to the food he ate. So naturally, Hoelzel decided to eat a slew of calorie-less, inedible substances in an attempt to get rid of hunger altogether. For example, he’d eat the cob instead of the corn, and the peel rather than the actual banana.

Eventually, Hoelzel moved on to other less desirable options, guzzling down all kinds of things ranging from charcoal, chalk, sand, sponge, hair, wool, and feathers. He developed quite the taste for surgical cotton, though (yum?).

Unfortunately, Hoelzel had a hard time finding a forum to express and foster his research until he met University of Chicago physiologist, Anton Julius Carlson. An expert in digestion, Carlson was eager to utilize Hoezel’s strange tastes for legitimate scientific experiments.

Together, the two tried to see if going without food for long periods of time could get rid of hunger. (Spoiler alert: It didn’t). They also tested how long certain foods took to go through Hoelzel’s digestive system; ingesting things like glass balls, gravel, silver wire, knotted twine and gold pellets, the pair found that gold pellets take the longest to go through your digestive system, while twine makes it out in about 90 minutes.

But before you write Hoelzel off as history’s human garbage disposal, he did make some legitimate advances in the field of digestion. For one, he was one of the first scientists to suggest that overeating could possibly lead to death. His love of surgical cotton also led him to invent cellulose flour, which can be found in many diet products to make you feel fuller on less calories.

So the next time you think about advancements in weight loss, tip your hat off to Frederick Hoelzel; if it wasn’t for his strange need to eat glass, we may not know as much as we do about digestion.

To learn more, watch the video above.