A hard drinking parting life style will definitely hurt your bodybuiding and I think that goes without saying.
1.It's hard on the liver. If you compromise the function of this organ you will have little energy.
2. It's a lot of calories. Drink 8 beers at 150 calories each then know that hunger at 2 AM as you swallow burgers, fries, and other food.
3. It really dehydrates you and also causes a loss of electrolytes. Any one who runs for fitness can tell you that running the day after drinking really kills endurance.
4. It reduces testosterone and also increases the aromatase conversion of testosterone to estrogen. How many heavy drinkers develop boobs and beer guts having that soft look.
I am typing this with with a major hang over from my over night trip to the casino.