The term natural bodybuilding is a weird term,
there really is'nt anything natural about what we do with our training, are diet, etc.
I guess most people feel that if you are using steriods then you are not natural, of course someone will argue that test is natural right.
Some supplements work better than certain drugs, for example I know of a few people who have used clenbluterol during a specific time and the Ephedrine/caffeine/asprin stack at another time, and they swear that clen was weak compared to the results that they got on the ephedrine stack.
Also things such as prohormones, despite the Mark Mcquire rap, are no where near the effectiveness of even a weaker steriod such as Winstrol for example. I personally think that prohormones got a bad rap.
Everything from protein powder to creatine are provided in enhanced form to create a supplement that produces results better than old school liver tablets and mega mass 2000.
Not to mention the hormones, chemicals and over manipulated food products we consume, I don't think any of us has been natural since the 19th century.
As supplements become better, as technology improves, there will be supplements that will be able to manipulate are DNA to produce bigger and more ripped muscles, and there is a possibility that some of this stuff will eventually be in supplement stores.
The line is already bluring, and it will continue to do so.
Many people feel that anything, short of anabolics themselves, is considered natural. I would agree....to a point.
The big issue is concentration. My rule of thumb for buying supplements is that doing so is for getting a high amount of nutrients that would be extremely difficult (if not downright impossible/impractical) to get from regular food.
Take whey protein, for instance. Whey naturally occurs in milk, but it makes up only 20% of milk's total protein value. In order to duplicate the amount of whey protein found in your average 100% whey RTD/MRP, you'd have to drink nearly TWO GALLONS of moo juice.
Caffeine is also natural. But, most fat burners have, in just 4-6 pills, the caffeine equivalent of a dozen or so cups of coffee. Even simple supplements like Vitamin C are super-concentrated. 2 pills equal a buttload of oranges or grapefruits.
And creatine???. Serge Nubret mentioned, in an article for MuscleMag International, that he was into the creatine things decades ago. Only, he got his the old-fashioned way from eating several pounds of beef or horsemeat, which he could afford due to the money he made as a movie star in France.
But, who here is going to eat a dozen pounds of meat to get 5 grams of creatine?? Not ME!!! And that's just for maintenance. What about the loading phase???
The line here, with regards to hormones is boosting one's own hormone output vs. using synthetic (or chemically-altered) hormones. Doing the former is considered "natural"; doing the latter is not.