Horace Fletcher is best known for starting a food fad in that came to be known as Fletcherism. This early 20th century fad involved, in part, chewing your food A LOT.
Research:

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Crowninshield, Francis W. “Manners for the Metropolis: An Entrance Key to the Fantastic Life of the 400.” New York. D. Appleton and Company. 1909. Via Babel Trust. https://babel.hathitrust.org/cgi/pt?id=uc1.31175009622302
Feltman, Rachel. “Fact: Horace Fletcher became a millionaire lifestyle influencer by telling people to chew as much as possible.” Popular Science. 4/26/2021. https://www.popsci.com/story/science/weirdest-thing-fletcherism-wawa-genetic-testing/
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Franklin, Deborah. “Chew, Chew, Chew!” NPR. 7/13/2009. https://www.npr.org/sections/health-shots/2009/07/chew_chew_chew.html/
Kean, Sam. “Disappearing spoon: Chewing it Over—and Over and Over and Over.” Distillations. Podcast. 5/4/2021. https://www.sciencehistory.org/distillations/podcast/chewing-it-over-and-over-and-over-and-over
"Horace Fletcher." Dictionary of American Biography, Charles Scribner's Sons, 1936. Gale In Context: U.S. History, link.gale.com/apps/doc/BT2310013484/GPS?u=mlin_n_melpub&sid=bookmark-GPS&xid=e3d11c0e. Accessed 13 Dec. 2022.
Levenstein, Harvey A. “Revolution at the Table: The Transformation of the American Diet.” Berkeley : University of California Press. 2003.
New York Times. “HORACE FLETCHER DIES IN COPENHAGEN; Dietetics Expert Was Originator of a System for Proper Mastication of Food. HIS EXPERIMENTS AT YALE Official Food Economist Taught ‘Fletcherism’ to 8,000,000 Starving Belgians During the War.” 1/14/1919. https://www.nytimes.com/1919/01/14/archives/horace-fletcher-dies-in-copenhagen-dietetics-expert-was-originator.html
Temple, Holly Eliza. “Repast: Horace Fletcher, the Original Food Faddist.” This Is Mold. 5/21/2021. https://thisismold.com/profile/repast/repast-horace-fletcher-the-original-food-faddist
Walthausen, Abby. “Fletcherizing Was the Juicing of the 1890s.” MyRecipes. 2/13/2018. https://www.myrecipes.com/extracrispy/fletcherizing-was-the-juicing-of-the-1890s
Roach, Mary. “How Many Times Should You Chew Your Food?” Adapted from Gulp: Adventures on the Alimentary Canal. Slate. 4/10/2013. http://www.slate.com/articles/health_and_science/medical_examiner/2013/04/excerpt_of_mary_roach_s_gulp_how_many_times_should_you_chew_a_bite_of_food.html
Fletcher, Horace. “Menticulture; or, the A-B-C of True Living.” Chicago. A.C. Mcclurg & Company. 1895.
Fletcher, Horace. “Happiness as Found in Forethought Minus Fearthought.” New York. Frederick A. Stokes Company. 1898.
Fletcher, Horace. “That Last Waif, Or, Social Quarantine: A Brief.” New York. Frederick A Stokes Company. 1898, 1909.
Fletcher, Horace. “The New Glutton, Or, Epicure.” New York. Frederick A Stokes Company. 1899, 1903.
Fletcher, Horace. “A.B.C. of Snap Shooting.” San Francisco. Published by the Author. 1880.
Fletcher, Horace. “The A.B.-Z. of Our Own Nutrition.” New York. Frederick A Stokes Company. 1903.
Fletcher, Horace. “Fletcherism: What It Is, Or, How I Became Young At Sixty.” Frederick A. Stokes Company. 1913.
Chittenden, Russell H. “Physiological Economy in Nutrition.” Popular Science Monthly Volume 63 June 1903. https://en.wikisource.org/wiki/Popular_Science_Monthly/Volume_63/June_1903/Physiological_Economy_in_Nutrition
Chittenden, Russell H. “Physiological Economy in Nutrition.” Popular Science Monthly Volume 63 June 1903. “The Influence of Diet on Endurance and General Efficiency.” Popular Science Monthly Volume 71 December 1907. https://en.wikisource.org/wiki/Popular_Science_Monthly/Volume_71/December_1907/The_Influence_of_Diet_on_Endurance_and_General_Efficiency
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