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One night in 1731, Cornelia di Bandi burst into flames. When the 62-year-old Italian countess was found the next morning, her head and torso had been reduced to ash and grease.

Only her arms and legs remained intact. After examining what was left of her body, a local physician concluded, in a report cited years later, that the conflagration “was caused in her entrails” by the variety of combustible materials to be found there, including alcohol and fat, “an oily liquid … of an easily combustible nature.” An early instance of what would come to be known as “spontaneous human combustion,” di Bandi’s case was one of many later studied by the French agronomist Pierre-Aimé Lair. If there was a common denominator to these otherwise unexplained phenomena, Lair concluded, it was the fact that most of them involved corpulent older women with a penchant for drink, thus combining fat and alcohol in a literally explosive mix. In addition to the fuel provided by excess body fat, which was rendered even more combustible when “penetrated by alcoholic substances,” surplus fat was said to create higher levels of hydrogen, making the body especially flammable. Lair concluded:

Thus there is no cause for surprise that old women, who are in general fatter and more given to drunkenness, and who are often motionless like inanimate masses, during the moment of intoxication, should experience the effects of combustion.

This post is adapted from Forth’s upcoming book.

Whatever Lair might have thought about fat old ladies who drank too much, in his report fat is about little more than the chemicals that composed it and the properties that rendered them combustible. Scientifically breaking the stuff of life down into its components was part of a general process of quantification that gained momentum during the 17th century to become pervasive in the 18th and 19th.

This was the period during which corpulence underwent a process of medicalization that would eventually contribute to our present views of obesity as a disease. Older ideas about fatness and mirth were reconceptualized in more mechanistic terms, which would only gain momentum in the following years. With the development of height and weight tables in the 19th century, the stage was set for the further development of ideas about metabolism, nutritional requirements, and eventually the body-mass index of our own time. But at the start of the modern era, fat played a very different role in Western cultures—that of a medical commodity.

Whether procured from plant, animal, or human sources, in one form or another fat has been an important element in the European pharmacopoeia since ancient times. For reasons that are not quite clear, a medicinal interest in human fat was especially pronounced in the 16th and 17th centuries. In 1543, the physician Andreas Vesalius instructed anatomists who boiled bones for the study of skeletons to carefully collect the layer of fat “for the benefit of the masses, who ascribe to it a considerable efficacy in obliterating scars and fostering the growth of nerves and tendons.” Vesalius knew what he was talking about. At the time, human fat was widely considered—and not just by “the masses”—to be efficacious in healing wounds, and was typically harvested from the recently deceased. In October 1601, after a particularly bloody battle during the Siege of Ostend, Dutch surgeons descended upon the battlefield to return with “bags full of human fat,” presumably to treat their own soldiers’ wounds.

If the fat of warriors was efficacious, that of executed criminals was easier to lay one’s hands on. What was called “poor sinner’s fat” was rendered from the bodies of the recently executed and used to treat sprains, broken bones, and arthritis. Beyond such uses, human fat was also prescribed as a painkiller or to treat sciatica and rheumatism, while dead men’s sweat was collected for the treatment of hemorrhoids. Until the mid-18th century, executioners in the city of Munich, who often prescribed and administered homemade remedies from the corpses of their doomed clients, had a lucrative trade in the fat they delivered to physicians by the pound.

Knowing what would become of their corpses was a source of great anguish for the condemned, many of whom believed in the Christian doctrine of the resurrection of bodies and were not consoled by the thought that their fat, flesh, blood, and bones might be parceled out for the benefit of others. Still, business was business, and against the wishes of donors, executioners continued to supply fat, blood, and other body parts to those willing to buy them. And it wasn’t just ordinary people buying such things. The wise druggist kept large supplies of human fat (Axungia hominis) on hand alongside numerous other solids and liquids derived from human corpses, a class of materia medica known as “mummy.” If fortune smiled on the fat trade when the rate of executions increased, it would have been positively beaming during the Terror days of the French Revolution. According to some reports, certain Parisian butchers started offering their customers an exciting new item: graisse de guillotiné, supposedly procured from the corpses of the freshly executed.


What was it about human fat that made it so sought-after? And what was so special about the fat of slain criminals in particular? The practice no doubt echoes the Catholic cult of holy relics, whereby saints were considered to be fully present in their bodies after death, as well as in the objects they touched. Yet this mystical appreciation explains only so much, and most executed criminals were no saints. Rather, the use of fat for medical purposes was perceived as a natural practice rather than a magical one, and thus was based on assumptions about the physical properties of the substance itself. Despite the apparent obsolescence of many of these beliefs, the claim that fat could heal wounds was not entirely misguided. Physicians today know that adipose tissue is highly “angiogenic,” meaning that it promotes the growth of new blood vessels from preexisting ones.

Early-modern people may have used fat in this way simply because it seemed to work. The reasons they gave for why it worked seem less convincing to most modern readers. According to the 16th-century Swiss physician Paracelsus and his followers, some of the vital force of the human being lingered in the body after death. This vitality, they contended, was strongest in the bodies of healthy young men who had died violently, especially—as in the case of an execution—when death came so swiftly that the life force had no time to evacuate the body. The provenance of this insight is uncertain, and even Paracelsus admitted to having received much of his medical knowledge from executioners trading in such substances. Nevertheless, the use of human fat remained widespread among laypeople and doctors alike, even among more orthodox Galenic physicians.

This well-known trafficking in human fat inevitably gave rise to fears that the precious matter might be harvested in less legitimate ways, perhaps for nefarious purposes. This fear was made plain in Spanish encounters in the New World. The soldier and chronicler Bernal Díaz del Castillo recorded how, following his first battle with the Tlascans in the Andes, he opened up the body of a plump slain Indian to dress his soldiers’ wounds with the dead man’s burned fat, and that in subsequent battles more Indian fat was used to heal wounded Spaniards. This was standard medical procedure among the conquistadors, another of whom—Hernando de Soto—was also said to have used Indian fat as a medicine.

Yet harvesting fat was a boon for sailors, too. Before leading the expedition that would bring down the Aztec empire, Hernán Cortés supposedly caulked 13 boats using the fat of the dead. Insofar as they too ascribed great powers to fat, the native population was understandably terrified by such behavior. In the Andes, rumors that the Spanish were exporting boatloads of fat back to Spain for medical purposes prompted the largest native rebellion of the first 200 years of Spanish rule. So durably entrenched did this fear become that, to the present day, Andeans tell stories about a bogeyman called the pishtaco (often depicted as a white man) who harvests Indian fat for medical and cannibalistic purposes. According to the missionary Jean-Baptiste Labat, similar concerns caused alarm among Africans who had been sold into slavery. Upon disembarking in America, the frightened captives told one another, their fat and marrow would be extracted and melted to make oil for the Europeans.

Concerns about the illicit harvesting of fat were not only by-products of colonial violence. Back in Europe, allegations of unauthorized fat extraction cropped up in numerous contexts. In a tradition extending back to the Middle Ages, especially in Germanic cultures, many thieves believed that their nocturnal pilfering would go unnoticed if they burned a candle made of human fat or the fingers of dead babies. As long as these “thieves’ candles” burned, it was said, burglars acquired powers of invisibility while homeowners would remain blissfully asleep. So powerful was this belief that in the 16th and 17th centuries, several thieves were convicted of murdering people just to make such candles. How ironic, then, that the murderers’ own fat would probably have been parceled off after their executions, to be used in medicines and other concoctions.

That human fat would be a mainstay in European pharmacies is thus not all that surprising. Yet the fact that druggists kept supplies of human fat and other body parts on hand does not mean the practice always had the seal of approval of medical specialists, many of whom had long argued that there was nothing special about human as opposed to any other kind of fat. In fact, by the mid-18th century, professional medical interest in human fat had already started to wane. “At present,” wrote the physician John Hill, “we are grown wise enough to know, that the Virtues ascribed to the Parts of the human Body are all either imaginary, or such as may be found in other animal Substances.” Such disapproval was compounded by a growing competition between doctors and executioners for access to dead bodies, the result being that the procurement of corpses was eventually taken out of the hands of executioners altogether.

Despite these changes, it took more than the frowning of a few doctors to stamp out the clandestine trafficking in human fat. A thriving fat trade had been reportedly operating for years out of the dissecting theaters of Paris. Its eventual discovery in the early 19th century was kept quiet for fear of alarming the public. Before being caught red-handed by the police agents who had been tipped off to their activities, medical assistants connected to various dissecting rooms had joined forces with their counterparts at the Faculty of Medicine to bring the fat to the people. They were hardly discreet about their activities, which seem to have been well known to everyone except the faculty administrators. Police raids revealed that at least four of the entrepreneurs had been storing the stuff at home. One was caught with massive amounts of it in his apartment. Another, presumably lacking more suitable containers, had filled two decorative sandstone fountains with purloined fat. While a fair amount was sold to medical charlatans and used to grease the wheels of medical carts, it was the city’s enamelists and fake-pearl makers who benefited most from this trade, thinking that they were receiving fat procured from horses or dogs. Or so they said.


This post is adapted from Forth’s upcoming book,  Fat: A Cultural History of the Stuff of Life.

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