“A diet is what helps a person gain weight more slowly”

“A diet is something that helps a person gain weight more slowly.—Bill Copeland” is a jocular line about dieting that was printed in February 1976 newspapers. “A diet is what helps a person gain weight more slowly” is another version of the Copeland quote that was published in 1976.
 
Bill Copeland is a common name and biographical details are not known.
 
     
18 February 1976, Indianapolis (N) Star, Earl Wilson syndicated entertainment column, pg. 29, col. 2:
WISH I’D SAID THAT: A diet is something that helps a person gain weight more slowly.—Bill Copeland.
   
Google Books
The Reader’s Digest
Volume 109
1976
Pg. 167:
A DIET is what helps a person gain weight more slowly. — Bill Copeland in Sarasota, Fla., Journal
   
Google Books
Modern English in action [Level 8]
By Henry I Christ and Jerome Carlin
Lexington, MA: D.C. Heath and Company.
1978
Pg. 484:
A diet is what helps a person gain weight more slowly said Bill Copeland.
 
Google Books 
Another Treasury of Clean Jokes
By Tal D. Bonham
Nashville, TN: Broadman Press
1983
Pg. 112:
Diet: What helps a person gain weight more slowly.
 
Google Books
The World’s Greatest Wacky One-Line Jokes
By Bob Phillips
Eugene, OR: Harvest House Publishers
2005
Pg. 32:
A diet is what helps a person gain weight more slowly.
   
Twitter
NYC Health&Nutrition‏
@Nutrition_NYC
Diet: The thing that helps a person gain weight more slowly.
We do not promote diets, we promote a better lifestyle!
6:42 PM - 2 May 2013
 
Twitter
P.L. Klein, Author‏
@PLKlein_Author
“A diet is what helps a person gain weight more slowly.” ~ Bill Copeland #QuickQuotes #PLKleinAuthor http://plklein.com
12:51 PM - 26 Oct 2015