Dr. Sanjay Gupta is now officially Dr. Buzzkill ... 'cause the CNN correspondent tells TMZ Sports, a "beer coat" will NOT keep you warm at frigid Super Bowl XLVIII -- and could actually mess you up badly.
For most fans ... booze goes hand-in-hand with the big game -- but with it going down outdoors, at Met Life Stadium this year ... we asked the good doc if it's still a good idea to swill alcohol in what's expected to be freezing February temps.
The news ain't good ... 'cause the Gup says even though getting wasted might make you feel warm ... it actually makes your body lose more heat.
Yeah, we know ... goes against everything you've ever heard or done, but watch the clip for the scientific explanation. It's interesting, and a great reason to watch from your couch.