I'd say smoking definatley.....hinders muscle development....and alcohol....But only if your smoking everyday!If your just getting hgh on weekends then it's ok....

Other people may say different but I'm only going by my own experiance ....When I worked out at school I piled on the muscle and lived drug free and ate well.....At Uni I played Rugby and Struggled build muscle through all the drink and ganja....Also during my gap year I smoked away all that bulk...You can see it in ones face if they've lost weight due to months of the stoner lifestyle