For as long as people have been watching their figure, diet gurus have been there to tell us how best to shed pounds and keep in shape. According to legend, William the Conqueror went on a liquid diet (of nothing but alcohol, naturally) when he found himself too large to ride his favorite horse. Between bouts of feasting, the notoriously bulky Henry VIII still observed fast days—although with “soup, herring, cod, lampreys, pike, salmon, whiting, haddock, plaice, bream, porpoise, seal, carp, trout, crabs, lobsters, custard, tart, fritters and fruit” all on his table, even his leaner days were a lavish banquet. Lord Byron famously advocated a diet of vinegar-drenched potatoes to keep himself trim. And in the later 19th and 20th centuries, popular solutions to obesity ranged from deliberately infecting yourself with a tapeworm, to spitting out any food that didn’t turn to liquid after chewing it 30 times.

These days, thankfully, people have ceased giving themselves gut parasites and drinking themselves into oblivion in the name of losing weight, but one weight-loss regimen that has survived the test of time is the low-carb diet.

Nutritionists might be divided over the benefits and detriments of diets that replace carbohydrates with increased proteins and fats, but there’s no denying their popularity. At the height of the Atkins Diet fame in the early 2000s, 1 in 11 people in the United States were reportedly following Robert Atkins’s directions to cut bread, pasta, and rice from their diets while eating all the meat, eggs, and dairy products they wanted. But years before Atkins came along, there was the Banting Diet: a low-carb regimen championed by the most unlikely of health gurus—an overweight London undertaker.

Born in London in 1797, William Banting came from a family of funeral directors; in fact, they were the official Funeral Directors to the Royal Household. The success of the family business paid for a comfortable lifestyle, and Banting lived for much of his life in a four-story Georgian townhouse in Kensington, one of London’s wealthiest neighborhoods. Although his work kept him relatively active—and he claimed not to give in to “excessive eating, drinking or self-indulgence of any kind”—by his mid-thirties Banting was nevertheless struggling with his size, and had begun consulting some of the city’s finest doctors in an attempt to lose weight.

The first merely advocated “increased bodily exertion,” as he later recalled, and in response Banting took up rowing on the Thames first thing in the morning. This certainly built up his strength, but had the adverse effect of simultaneously increasing his appetite, leaving him no further forward. Another advocated brisk walks and exposure to sea air, but it too had little positive effect. Starvation diets and living “upon sixpence a day” followed, as did daily horse rides, purgative medicines, Turkish steam baths, and trips to medicinal spas all over the country, but still, in Banting’s own words, “the evil still gradually increased.” After years following an array of treatments and remedies, he had succeeded in losing just six pounds.

Now middle-aged, Banting was so obese that even tying his shoelaces became a chore. He took to walking downstairs backwards to ease the pressure on his knees and ankles, his sight began to fail, and his skin began to be afflicted with painful boils and lesions. But just when things seemed hopeless, one of Banting’s doctors took a summer vacation—and in his absence he booked an appointment with another London surgeon, one named Dr. William Harvey.

As luck would have it, Dr. Harvey had just returned from a convention in Paris, and was keen to test out the newfound dietary theories of Claude Bernard, one of France’s foremost physicians, which he had heard there. And in William Banting, he had found the perfect guinea pig.

Dr. Harvey listened to Banting’s medical history, and after having asked him to list a typical day’s meals, prescribed him a precise diet plan prohibiting “bread, butter, milk, sugar, beer and potatoes.” Breakfast was now “four or five ounces of beef” with a small biscuit or some dry toast on the side. Dinner was no longer “meat, beer, much bread … and pastry,” but four or five ounces of fish, served with vegetables and washed down with “two or three glasses of good claret, sherry, or Madeira.” Tea time was “two or three ounces of fruit” and "a rusk or two" with some black unsweetened tea, while supper was the same amount of meat or fish, helped down by another glass of claret or “a tumbler of grog” at the end of the evening. Champagne, port, and beer, however, were all expressly forbidden.

Banting felt the effects of Dr. Harvey’s diet almost immediately. He reported sleeping better than he had in years, and his overall health quickly improved. More importantly, the weight soon began to disappear.

At his heaviest, 5-foot-5-inch Banting weighed 202 pounds; within a year, he weighed just 167 pounds. After a lifetime of obesity, Banting described Dr. Harvey’s diet as “simply miraculous,” and as a show of gratitude donated the princely sum of £50 to his favorite hospital (about £5500, or $7000 USD, today). But he didn’t stop there—Banting wanted everyone to know just how successful his diet had been.

In 1863, at the age of almost 66, Banting published a pamphlet—or rather, a “letter to the public”—entitled On Corpulence. In it, he outlined his struggles with his weight, his history of poor health, and the miraculous transformation that Dr. Harvey’s low-carb diet had brought about. The pamphlet’s mix of personal testimonial and straightforward health advice soon proved hugely popular, and the first edition, self-published at Banting’s own expense, quickly sold out. By the time it had made it to the fifth edition, 63,000 copies of On Corpulence had been sold in Britain, Europe, and all around the world.

Banting continued to follow Harvey’s dietary advice for the remainder of his life, and died in 1878 at the age of 81. After his death, On Corpulence continued to sell, while he and the story of his miraculous weight loss lived on in music hall songs, satirical cartoons, and even in the language itself: to bant soon came to mean “to diet” or “to watch what you eat,” and remains in use in some areas even today—a claim to fame that eluded even Robert Atkins.