The Cultural Encyclopedia of Baseball (1997) by Jonathan Fraser Light has an entire section dedicated to Fat and Weight (pg 250); here are some entries:
"A waist is a terrible thing to mind." - Terry 'Fat Tub of Goo' Forster (to / on David Letterman)
"I only eat two meals a day, I just like snacks." - Willie Horton (responding to a question about his weight gain in Spring Training)
"Mr. President (Dwight Eisenhower), I was on a diet for 25 years. Now that I'm makin' some money, I'm makin' sure that I eat enough to make up for the lean years." - Dizzy Dean (while golfing with the President & answering why he weighed nearly 300 pounds.)
"Watching Fernando Valenzuela force himself into a Los Angeles Dodgers uniform is something like seeing Kate Smith struggling to fit into a pair of Brook Sheilds' designer jeans." - Sports H.G. Reza
Source: The Cultural Encyclopedia of Baseball (1997, Jonathan Fraser Light)
The heaviest player in Major League history was Jumbo Brown who weighed two-hundred ninety-five (295) pounds and played from 1925 through 1941.