“I’m not fat—just short for my weight”

Height and weight charts have led to the jocular excuse that one has the right weight, but just has the wrong height. The American humorist Sam Levenson (1911-1980) said in 1952, “But I’m not really fat. It’s just that I’m 10 inches too short for my weight.”
 
The joke usually concludes with someone saying that the right height for such a weight is an exaggerated amount—often at least eight feet. The American comedienne Totie Fields (1930-1978) added the joke to her routine and said in 1964, “I’m not overweight. I’m just too short. For my weight, I should be about 12-feet-7.”
 
The similar saying of “I’m not overweight—I’m undertall” was popularized in 1979 by the overweight comic strip cat Garfield. Other similar sayings include “I’m not fat—I’m just easy to see,” “I’m not fat—I’m just big boned,” “I’m not fat—I’m just well-marbled,” “I’m not fat—I’m flooded,” “I’m not fat—I’m fluffy,” “I’m not fat—I’m cultivating mass,” “I’m not fat—I’m insulated,” “I’m not fat—I’m just so sexy, it overflows” and “I’m not fat—my stomach is just in 3D.”
 
       
5 September 1952, Morning Advocate (Baton Rouge, LA), “The Lyons’ Den” by Leonard Lyons, pg. 4A, col. 2:
Sam Levenson obeyed his doctor’s orders and lost 15 pounds in two weeks. The moonfaced humorist kept assuring his doctor: “But I’m not really fat. It’s just that I’m 10 inches too short for my weight.”
 
Google Books
August 1957, Farm Journal, pg. 19:
When those doctors said I was too heavy for my height I tried to convince them they were wrong; that I just was too short for my weight.
 
Google News Archive
7 March 1964, Sarasota (FL) Herald-Tribune, “It Happened Last Night” by Earl Wilson, pg. 46, col. 4:
Fat Girl Totie Fields: “I’m not overweight. I’m just too short. For my weight, I should be about 12-feet-7.”
 
29 June 1967, San Diego (CA) Union, “Point of View” by Donald Freeman (TV-Radio Editor), pg. C7, col. 1:
Jackie Gleason insists he really isn’t heavy—“I’m just short for my weight,” Jackie contends. “I should actually be about 8 feet 6 inches.”
 
Google News Archive
30 January 1969, Lewiston (ID) Morning Tribune, “Checking Up” by L. M. Boyd, pg. 16, col. 1:
WRITES an Ohio lady, “I’m not too fat. It’s just that I’m short for my weight. According to the tables, I should be 8 feet 9 inches tall.”
 
Google News Archive
9 June 1973, Windsor (Ontario) Star, “Totie Fields,” TV Magazine, pg. 26, col. 2:
A roly-poly 200 pounds, give or take a few ounces, Miss Fields explains away her corpulence: “I’m not really fat. I’m just short for my weight. I should actually be about 8 feet 6 inches, have an 18-inch waist through the center.”
 
Google Books
Planet of the Perfectly Awful People: a one act play
By Joseph Robinette
Chicago, IL: Dramatic Pub. Co.
1979
Pg. 18:
GROAN. I am not fat. I—I’m just too short for my weight.
 
10 March 1986, Toronto (Ontario) Star, “Excuses are blooming in T-shirts these days” by George Gamester, pg. A2:
I’M NOT FAT, claims one from Bruce Bryer of West Hill, JUST SHORT FOR MY WEIGHT. And I’M NOT OVERWEIGHT, explains another from George Karpati of Toronto, JUST UNDERTALL.