Harvey prescribed the regimen to Banting, who began dieting in August 1862. He ate three meals a day of meat, fish, or game, usually five or six ounces at a meal, with an ounce or two of stale toast or cooked fruit on the side. He had his evening tea with a few more ounces of fruit or toast. He scrupulously avoided any other food that might contain either sugar or starch, in particular bread, milk, beer, sweets, and potatoes. Despite a considerable allowance of alcohol in Banting’s regimen—four or five glasses of wine each day, a cordial every morning, and an evening tumbler of gin, whisky, or brandy—Banting dropped thirty-five pounds by the following May and fifty pounds by early 1864. “I have not felt better in health than now for the last twenty-six years,” he wrote. “My other bodily ailments have become mere matters of history.”

We know this because Banting published a sixteen-page pamphlet describing his dietary experience in 1863—Letter on Corpulence, Addressed to the Public—promptly launching the first popular diet craze, known farther and wider than Banting could have imagined as Bantingism. His Letter on Corpulence was widely translated and sold particularly well in the United States, Germany, Austria, and France, where according to the British Medical Journal, “the emperor of the French is trying the Banting system and is said to have already profited greatly thereby.” Within a year, “Banting” had entered the English language as a verb meaning “to diet.” “If he is gouty, obese, and nervous, we strongly recommend him to ‘bant,’” suggested the Pall Mall Gazette in June 1865.

The medical community of Banting’s day didn’t quite know what to make of him or his diet. Correspondents to the British Medical Journal seemed occasionally open-minded, albeit suitably skeptical; a formal paper was presented on the efficacy and safety of Banting’s diet at the 1864 meeting of the British Medical Association. Others did what members of established societies often do when confronted with a radical new concept: they attacked both the message and the messenger. The editors of The Lancet, which is to the BMJ what Newsweek is to Time, were particularly ruthless. First, they insisted that Banting’s diet was old news, which it was, although Banting never claimed otherwise. The medical literature, wrote The Lancet, “is tolerably complete, and supplies abundant evidence that all which Mr. Banting advises has been written over and over again.” Banting responded that this might well have been so, but it was news to him and other corpulent individuals.

In fact, Banting properly acknowledged his medical adviser Harvey, and in later editions of his pamphlet he apologized for not being familiar with the three Frenchmen who probably should have gotten credit: Claude Bernard, Jean Anthelme Brillat-Savarin, and Jean-François Dancel. (Banting neglected to mention his countrymen Alfred William Moore and John Harvey, who published treatises on similar meaty, starch-free diets in 1860 and 1861 respectively.)