“The first thing you lose on a diet is your sense of humor.” is a dieting saying that has been printed on many images. The saying has been cited in print since at least 1979 (when it was said by Calgary Stampeders trainer Alex Recsky) and 1983, when it was printed on a T-shirt. Authorship is unknown.
 
   
24 November 1979, Calgary (Alberta) Herald, “Editors’ Quiz” by Susan Scott,  pg. G11, col. 2:
16) According to Stampeder trainer Alex Recsky, what is the first thing you lose on a crash diet?
Your sense of humor.
 
7 March 1983, Albuquerque (NM) Journal, pg. 21 ad:
The first thing you lose on a diet is your sense of humor
(Mervyn’s department store. The saying is shown on a T-shirt.—ed.)
 
Google Groups: alt.support.diet.low-carb
Valentine’s Day Question?
Carmen
2/10/03
(...)
The first thing you lose on a diet is your sense of humor.
   
Google Books
Lighten Up!:
The Authentic and Fun Way to Lose Your Weight and Your Worries
By Loretta LaRoche
Carlsbad, CA: Hay House, Inc.
2009
Pg. XI:
“The first thing you lose on a diet is your sense of humor.” — Anonymous
 
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Pimlico Flats ^..^
‏@pimlico_flats
Nick’s Thought for the Day “The first thing you lose on a diet is your sense of humor.”
3:22 AM - 29 Jan 2009
 
Google Books
Max Capacity Training:
How Unconventional Workouts Can Turn Minutes Into Muscles
By Samy Peyret
San Francisco, CA: Intelligent Laziness Books
2011
Pg. 146:
“The first thing you lose on a diet is your sense of humor.” - Author Unknown
 
Google Books
Smart People Don’t Diet:
How the Latest Science Can Help You Lose Weight Permanently
By Charlotte Markey
Philadelphia, PA: Da Capo Press
2014
Pg. 21:
The first thing you lose on a diet is your sense of humor. —Author Unknown
   
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The 3 Weeks Diet
September 9, 2015 ·
The first thing you lose on a diet is your sense of humor.