A popular food riddle is:
Q: How many hamburgers can you eat on an empty stomach?
A: One. After that, your stomach isn’t empty.
The riddle has been cited in print since at least 1849, when it was phrased, “How many soft boiled eggs could the giant Goliah (Goliath—ed.) eat on an empty stomach?” “Oysters” replaced eggs in 1927, “buns” was used in 1929, “apricots” in 1939, “clams” in 1940, “pancakes” in 1955 and “hamburgers” in 1977.
8 January 1849, The Daily Sanduskian (Sandusky, OH), pg. 2, col. 3:
A PROFITABLE TRADE IN RIDDLES.
By MRS. St. SIMON.
(...)
Thus, for example, the first asked: “How many soft boiled eggs could the giant Goliah eat on an empty stomach?”
All said that it was impossible to answer that question, and each paid his twelve kreutzers.
But the Jew said—“One; for he who has eaten one egg, cannot put a second upon an empty stomach,” and the other paid him twelve kreutzers.
Chronicling America
10 March 1849, The North Carolinian (Fayetteille, NC), pg. 4, col. 3:
A PROFITABLE TRADE IN RIDDLES.
Translated from the German by Mrs. St. Simon.
(...)
Thus, for example, the first asked: “How many soft boiled eggs could the giant Goliah eat on an empty stomach?”
All said that it was impossible to answer that question, and each paid his twelve kreutzers.
But the Jew said—“One; for he who has eaten one egg, cannot put a second upon an empty stomach,” and the other paid him twelve kreutzers.
20 November 1927, The Sunday Courier and Journal (Evansville, IN)< "Guess These Riddles," Magazine Section, pg. 3, col. 4:
How many oysters can a hungry man eat on an empty stomach?
1 July 1929, Aberdeen (SD) Evening News, pg. 4, col. 4:
‘TIS TRUE
“How many buns could you eat on an empty stomach?”
“About a dozen.”
“You’re wrong. You could eat only one, because after that your stomach wouldn’t be empty.”
Google News Archive
15 April 1939, The Evening Citizen (Ottawa, Ontario), pg. 20, col. 5:
How many apricots can you eat on an empty stomach? One, because after that your stomach is not empty.
Google Books
Mathematical Clubs and Recreations
By Samuel Isaac Jones
Nashville, TN: S. I. Jones Company
1940
Pg. 168:
How many clams can you eat on an empty stomach?
Google News Archive
27 April 1940, Owosso (MI) Argus-Press, “Riddles,” pg. 3, cols. 3-4:
How many eggs can you eat on an empty stomach? Helen Havnes
Only one. After you eat one egg your stomach is no longer empty.
Google Books
Handbook of Indoor Games and Stunts
By Darwin Alexander Hindman
Englewood Cliffs, NJ: Prentice Hall
1955
Pg. 296:
How many pancakes can you eat on an empty stomach? ANSWER: Just one; then your stomach is no longer empty.
12 August 1962, South China Sunday Post-Herald (Hong Kong), “Riddles,” pg. 17, col. 3:
How many cakes can you eat on an empty stomach?
One, after which your stomach isn’t empty.
Google News Archive
25 May 1977, Gadsden (SC) Times, ‘“Kid Stuff,” pg. 7, col. 1:
How many hamburgers can you eat on an empty stomach?
One. After that your stomach isn’t empty.
Google Books
Rats, Spiders & Love
By Bonnie Pryor
Illustrated by J. Winslow Higginbottom
New York, NY: Dell
1989, ©1986
Pg. 74:
“How many pieces of pizza can you eat on an empty stomach?” Sam asked.
Mrs. Wilson patted her plump stomach. “I could probably eat about six, but I am sure that isn’t the answer,” she chuckled. “How many?”
“Only one. After that your stomach isn’t empty,” Samantha told her.
Google Books
The World’s Most Crazy, Wacky, & Goofy Good Clean Jokes for Kids
By Bob Phillips
New York, NY: Galahad Books
1999
Pg. 174:
How many hamburgers can you eat on an empty stomach?
Only one, because after that your stomach is no longer empty.
Google Books
Chelm Stories My Saba Sent Me
By Yoni Elkins
Lulu Publishing (Lulu.com)
2015
Pg. 61:
How many cookies can you eat on an empty stomach?” Moshe thought and thought. “How big?” “Medium size,” said the man. Moshe thought again and said “about five.” The man smiled “You are wrong. You can only eat one. After you eat one, your stomach’s not empty any more.