... at least, that's according to Julian Edelman, who revealed this week that's how his former quarterback seriously got down at team dinners prior to Patriots game days.

The ex-New England wide receiver went in-depth on the topic with People ... saying he found out about Brady's weird eating quirk when the Pats would get the same food catered every night before games -- including chicken wings.

"Tom would always have one chicken wing for his guilty pleasure before we would huddle off to bed," Edelman said.

"A single chicken wing."

It's shocking, even for Brady's standards, although Edelman swore that's simply the way Brady operated ... choosing to balance his diet with 80 percent vegetables and grains and 20 percent lean meats and fish.

"He does live by that diet," the wideout said. "He does practice what he preaches. We used to get in arguments all the time about it."

The cheat meal, of course, is a far cry from someone like Dwayne Johnson -- who takes his diet seriously .... but has been known to indulge in thousands of calories in one sitting from time to time.