College freshmen often gain weight with many dining hall choices and available snacks during late-night study hours. The term “freshman five” (or “freshman 5”) for the number of pounds added during the year is rare, but “freshman ten” (or “freshman 10”) and “freshman 15” (or “freshman 15”) have been commonly used since at least the early 1980s.
   
“My COVID-19 is the most weight I’ve gained since my Freshman 15” is a joke that was told during the 2019-20 coronavirus outbreak.
   
     
Wikipedia: Freshman fifteen
The Freshman fifteen refers to an amount (somewhat arbitrarily set at fifteen pounds) of weight often gained during a student’s first year at a college or university.
 
The expression is commonly used in the United States and Canada. In Australia and New Zealand it is sometimes referred to as First Year Fatties, Fresher spread, or Fresher Five - the latter referring to a five kilogram gain).
 
The purported causes of this weight gain are increased alcohol intake and the consumption of fat and carbohydrate-rich cafeteria-style food and fast food in university dormitories. Many dining halls in United States universities are all-you-can-eat style and offer copious dessert choices. In addition, lack of sleep may lead to overeating and weight gain, because it lowers the level of leptin. Other causes include malnutrition, stress, and decreased levels of exercise. All of these factors can affect each person in a different way. Studies confirm many of these causes. Colleges and universities have recently been cracking down on this common problem and are trying to educate people on how to prevent it. This problem has grown so much that students are focusing on how to stop the freshman fifteen before it even happens.
 
Word Spy
freshman 15
n. The number of pounds that many students gain in their first year of college; the often observed phenomenon of weight gain among first year college students. Also: Freshman 15, Freshman Fifteen.
(...)
Earliest Citation:
The 1,820 freshmen at Northwestern are almost grown-ups now, old enough to live on pizza and candy, go out for a midnight snack and stay up till 3 a.m.
 
It was all supposed to be wonderful, and sometimes it is, but they are also getting fat and feeling sleepy. They miss their homes, their rooms, their friends and, most of all, their parents, terribly.
 
They have freshman blues and Freshman 15, the latter referring to how many pounds many freshmen gain.
—Barbara Brotman, “Forget the calendar, for freshmen this is a leap year for growing up,” Chicago Tribune, November 5, 1985
 
Mount Holyoke College Freshman Handbook
For the Class of 1966
From Their Sister Class. 1964
1962
Pg. 17:
CANDLELIGHT, COFFEE AND CONVERSATION
The meals on Wednesday evening and Sunday noon are known as “Gracious Living.” These are times of metamorphosis from the perpetual bermudas and sweatshirt to stockings, heels, and more formal attire.
(...)
TEA AND CRUMPETS; MILK AND CRACKERS
To help you add those extra freshman ten pounds, milk and crackers are set out each night at 9:45, a welcome break in the study routine.
     
Google Books
Mademoiselle
Volume 85
1979
Pg. 134:
The “freshman ten” is more monster than myth; proof is in the pudding (or pastry or candy machine or cake.)
   
Google Books
Selective Guide to Colleges
By Edward B. Fiske
New York, NY: Times Books
1982
Pg. 186:
Students even have a name — “The Freshman Fifteen” — for the extra pounds enjoyably gained the first year. (After that they can take advantage of the dining hall’s Scarsdale Diet menu.)
 
21 December 1983, State Center (IA) Enterprise, “The Trials and Tribulations of a Freshman College Student” by Karen Knights, pg. 6, col. 4:
Compared to the “eat it or leave it” tactics of high school, the food’s not bad at all. (Maybe that’s why there’s a rumor about the infamous “Freshman 15”—pounds gained, that is!)
 
Google News Archive
10 August 1984, Pittsburgh (PA) Post-Gazette, pg. 3, cols. 1-2:
Bulge: College freshman year a puzzler as students get 9 pounds heftier
By Jeff Barker
Associated Press Writer
STATE COLLEGE, Pa.—Be it anxiety or natural body change, college students put on a lot of weight their freshman year, and starchy dormitory food is not the reason, according to a study released yesterday.
(...)
Students often attribute the weight gain, known on many campuses as the “freshman ten,” to starchy dormitory food, the study said.
 
Google Books
Understanding Statistics
By Bruce J. Chalmer
CRC Press
1986
Pg. 144:
Suppose that you wish to study whether college students gain weight, on the average, during their first year on campus. (This phenomenon is known to believers as “the freshman ten” — pounds, that is.)
     
OCLC WorldCat record
Analysis of the “freshman ten” : weight gain as a function of stress and coping style in a university sample
Author: Cynthia L Sullivan
Publisher: 1993.
Dissertation: Thesis (M.A.)—University of Maryland, Baltimore County, 1993.
Edition/Format:  Thesis/dissertation : Manuscript Archival Material : English
 
OCLC WorldCat record
The “Freshman 15”: Facts and Fantasies About Weight Gain in College Women
Author: C N Hodge; L A Jackson; L A Sullivan
Edition/Format:  Article
Publication: PSYCHOLOGY OF WOMEN QUARTERLY, 17, no. 1, (1993): 119
Database: British Library Serials
 
OCLC WorldCat record
The college dorm workout : fight the freshman fifteen in twenty minutes a day without starving to death
Author: Marthe Simone Vedral; Joyce L Vedral
Publisher: New York : Warner Books, ©1994.
Edition/Format:  Book : English
   
OCLC WorldCat record
Fighting the freshman fifteen : a college woman’s guide to getting real about food and keeping the pounds off
Author: Robyn Flipse; Marisa Bradanini; Marchelle Bradanini
Publisher: New York : Three Rivers Press, ©2002.
Edition/Format:  Book : English : 1st ed