The keto diet was accidentally discovered in 1862 by a funeral director who lost 52 pounds on a diet of cordial and meat

• The keto diet is a popular wight-loss strategy, but many people don't know that the high-fat plan has been around since at least the late 1800s.
• Victorian-era funeral director William Banting lost over 50 pounds in the 1860s on a diet remarkably similar to the eating plan we now know as keto.
• After eliminating starches and sugars from his diet, Banting said he felt more comfortable and happier than he had in decades. So he wrote a booklet describing his daily meal plan, hoping others might follow his lead.
• But even Banting admitted that a keto diet probably isn't right for everyone.

In the late 1800s, wealthy Londoner William Banting knew that many people were battling the same "insidious creeping enemy" that he was: fat.

Banting, a former funeral director, wanted to help. And finally, after three decades of his own failed attempts at losing weight, he'd found a promising way to shed pounds: a regimen remarkably similar to today's trendy keto diet.

The keto diet is designed to force the body into a state of ketosis, in which it burns fat for energy instead of carbohydrates. Carbs are our default energy source, but when you don't consuming any, the body goes into a fat-burning state to stay alive.

Banting didn't know his new diet was a ketogenic routine, but that was the effect - he strictly limited how much bread, sugar, beer, and potatoes he ate, subsisting instead on small quantities of meat, fish, vegetables, and of course the occasional "large cup of tea."

Banting's weight-loss success led him to believe that neither the public nor the medical community properly understood obesity. He knew that a non-expert like himself couldn't get his own case study published in a top medical journal, but he wanted to call attention to his method. So he wrote a free booklet in 1863 called "Letter on Corpulence, Addressed to the Public," in which Banting described what he'd been eating and how the diet made him feel.

The novel strategy "might almost be termed miraculous," Banting wrote, "had it not been accomplished by the most simple common-sense means."

Banting changed his eating completely but didn't starve himself

For most of his life, Banting had followed a fairly traditional British diet heavy on bread, sugar, beer, milk, butter, and potatoes. Then, in his sixth decade of life, Banting said, he "found the right man" in doctor William Harvey, who "prescribed a certain diet" that banished many of those foods. They were all too starchy and sweet, Harvey cautioned.

"At the first blush it seemed to me that I had little left to live upon," Banting wrote. But he soon found the diet to be "luxurious and liberal." In total, the regimen helped him lose 52 pounds.

Here's the sample daily menu Banting offered his readers:

The Victorian-era regimen Harvey suggested started with a morning tablespoon of cordial mixed into a glass of water that Banting called the "balm of life." He endorsed the occasional bedtime nightcap as well - a glass of gin, whiskey, sherry or brandy.

The diet wasn't perfectly keto - while a shot of alcohol or glass of red wine is generally considered a fine once-in-a-while habit for people on keto diets, drinking too much can throw people out of their fat-burning state, especially if cocktails involve mixers or juices. A bit of toast could push people out of ketosis and back into carb-burning mode.

Banting also nixed butter, a fat source that modern-day keto dieters adore. What's more, his plan may have relied more on red meat and protein than is healthy.

Read More: A cancer researcher who's been on the keto diet for 6 years explains how he does it

Still, the sugar-banning principle behind Banting's diet was the same as today's keto technique, which is used therapeutically to treat epileptic seizures and holds some promise for managing Type 2 diabetes cases. Some cancer researchers and doctors treating obese patients also suggest it.

A high-fat diet pioneer

Harvey's advice was hundreds of years ahead of its time, as other nutrition experts have only recently embraced sugar as a major contributor to the obesity epidemic. The idea that a low-carb, high-fat diet might benefit certain people was largely brushed aside by the medical community until ketogenic diets began being used clinically in the 1920s.

Banting was so dedicated to his cause, however, that he gave out the first two printings of his "Letter on Corpulence" free to readers. By the time the the third printing rolled around a few months later, Banting said he could no longer cover the costs, so he sold that edition at-cost, asking his readers for the six pence it cost to print the slim volume.

Banting's book became a bestseller: over 63,000 copies were sold in the UK alone in the 1860s.

He hoped, he said, "to confer a benefit on my fellow creatures... the same comfort and happiness I now feel."

Today, some people who follow a low-carb diet are still said to be "banting." Acclaimed South African exercise scientist and low-carb guru Tim Noakes, a self-proclaimed "Banting proponent" has even developed a foundation that aims to educate people "about the dangers of excessive sugar and carbohydrate consumption."

Banting managed to shed 50 pounds in his mid-60s

Banting's pamphlet described a torturous cycle of failed weight-loss attempts that may still sound familiar to many people. Even though Banting said he'd led a fairly active life, exercise hadn't decreased the size of his waistline. He recounted how once, on the advice of a surgeon friend, he'd started rowing a few hours every morning in order to lose weight. That plan didn't help because it only made him hungrier.

He also tried Turkish baths when those became popular, but only dropped six pounds that way.

"I could not stoop to tie my shoe," he wrote.

Banting described how he'd felt pained by the "remarks and sneers, frequently painful in society" that he'd endured as a fat man. These difficulties led him to sometimes avoid crowded places, he added.

He offered his new diet as a solution.

"I am now nearly 66 years of age, about 5 feet 5 inches in stature, and, in August last, weighed 202 pounds," Banting wrote in the first edition of the pamphlet. "I now weigh 167 pounds, showing a diminution of something like 1 pound per week."

In the second edition, Banting announced that his weight loss had continued: he was down 46 pounds and was 12.25 inches skinnier around his waist. When the third edition was published in December 1863, Banting proclaimed he weighed 150 pounds.

He also suggested that the diet improved his hearing, sight, and fitness level. "I have not felt so well as now for the last 20 years," he wrote.

But despite his own success, Banting discouraged anyone from trying the diet without "full consultation with a physician." That jibes with modern advice that no single diet strategy is right for everyone. (The keto diet is especially risky for people with kidney or liver issues and those who've had gout. Pregnant women shouldn't try it, either.)

Banting died in 1878, about 14 years after the third edition of his booklet was published. He remained a keto evangelist (though he didn't yet have that term), believing that the diet was, "in a certain sense, a medicine."

As he wrote in the closing lines of his book: "I feel quite convinced [the diet] sweetens life, if it does not prolong it."