Whats the lifestyle BIG?
Diet, lifting, drugs (if chosen to use), goals.
Think about it this way, that male trainer on the show Biggest Loser, he watches what he eats, lifts weights, does cardio.... but is he a bodybuilder? no he's not, his goal is not to build huge muscles and perfect proportions while maintaining optimal bodyfat... his goal is to be fit and healthy, so he does these things...diet, weights, etc in a manner to get him to his gaols.
Someone like me, I do the same things he does: watch what I eat, lift weights, do cardio.... am I a bodybuilder, yes. Take out the competition aspect for a minute. I'm doing the exact same thing that the dude above is doing, but with different intentions, qty, organization etc....
He may eat healthy say like 2200 calories with a more balanced diet... where as I may eat healthy but say like 3500 calories with an emphasis on protein for muscle gains.
He lifts weights, but maybe he does particularly full body circuit training to focus on his fitness, where as I may be doing one muscle a day with a progressive resistance technique to emphasize muscle growth.
Does that make sense? Our lifestyles maybe similar, but they are not the same, primarily because our goals are different, and as a result we run our lifestyles differently.
