Tough to say, the body can get used to and overcome a lot. I imagine 6-8 drinks is enough to have an impact on hydration and normal functioning to some degree. Likely not night and day or hugely significant but I'd think if someone controlled for everything (which is impossible) you might get some type of significant result over a long enough period.
To be honest though, plenty of guys have gotten really big and really strong while drinking like that - probably even worse. A guy who lifted for Cuba told me a story about training outside while drinking beer and smoking cigarettes. This guy was a great lifter at that time too.
Not saying that this is a good model, or ideal behavior or that there isn't some tradeoff somewhere but simply that BBing has a massive "lifestyle" focus and seems to promote an idea that everything has to be absolutely perfect on a daily basis down to trace mineral intake to make decent progress. Then again you look at the training that is typical for BBing boards and the obcessive fear of losing etched abs that keeps calorie intake right at the margin, and I guess you do need to be perfect if you want to see results from that. If training is solid (like the type of stuff most are doing here in this section) and caloric intake is adequate, providing you don't screw yourself over too badly - you should do fine.
Now, I'm sure some nimrod will find this post and call it heretical and think I'm telling everyone to drink and smoke while they train, get blasted at night, and eat like a fat slob. That's not what I'm saying. Personally, I don't drink any more. It has nothing to do with lifting or muscle, I just feel better and never much cared for it anyway (although I've done more than my share of it). What I am saying is that if you are trying to achieve a goal, micromanaging the 1% to 3% stuff should be worried about after getting those big 40% blocks tuned up and out of the way first. If that goal is 'muscle', your blocks will be defined mostly by solid training and adequate caloric intake with reasonable balance - unless of course you have a real problem somewhere (i.e. you are drunk all the time). If your goal is 'bodybuilding lifestyle' well, maybe drinking should be a lot less and more infrequent - you'll also need some clown pants, a fanny pack, Ottomix, and a big drug budget so take that for what it's worth

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