system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What are the likely effects of heavy drinking on a person's overall mental and physical health over the course of a few years? And what makes someone an "alcoholic" versus a "heavy drinker"?

Say, for example, someone was drinking a little more than a gallon of cheap-o vodka every week (goes through about 4.75 liters a week) for a year or more... What kind of effects will that likely have on said person? If that person suddenly stopped drinking cold-turkey for three weeks for financial reasons and did not have any withdrawal issues, does that mean he or she is probably okay physically?

And would that amount make someone an alcoholic automatically, or are there other factors that make someone an alcoholic versus a heavy drinker?  

I am concerned about a loved one's drinking habits and am not sure I need to be because aside from being a little groggy in the morning and a little cranky until the day gets going, the amount of alcohol doesn't seem to be doing much negative impact to him.
gpt
First off you need to tell whatever person that quitting "cold turkey" could kill them...to go from almost a 5th(750ml) a day to nothing could lead to brain imbalances which would kill you. He needs to taper off or, preferably, see a specialist who will give him drugs while he sobers up.

Secondly, regarding the effects of someone who drinks that much- just google "encephalopathy". What now is just "waking up cranky" will eventually turn into essentially a mentally handicapped person. Encephalopathy is irreversible, btw.


Best thing you can do in the meantime is get the alky to take B1(thiamine) vitamins every day, that will help a lot as alcohol(ethanol) disrupts the thiamine distribution in the brain.

Bottom line: Almost any college age kid alky handle that amount of booze, but once you enter the "dirty 30's" and beyond- don't plan on living much past 50-60yo if you keep imbibing at that pace.