I read recently that a "heavy drinker" is defined as someone who drinks "five or more drinks in one session, four or more times a month."
I'll admit I chuckled at first and wondered if it was a joke, but in all seriousness this is right on the money really.
The vast majority of people I know would never dream of drinking five or more drinks in one session. And those that do would never do it four times a month.
Most people I know binge dean in college then became totally normal light drinkers.
I figure the doctors who came up with the daily limits, what are they, two drinks a day? They must be onto something.