Those who are lucky enough to build muscle without supplements often do so as a result of either not being able to afford expensive bodybuilding supplement options, hence forcing them to pursue natural muscle building methods, or wisely have a healthy fear of supplement health side effects. With long enough experimentation, certain bodybuilders stumble upon an effective natural bodybuilding program, but what about those who wish to avoid months or years of weeding through the false theories?
There is unfortunately not an easy several word answer to natural bodybuilding, simply because so many variables exist in regards to both weight training and diet (reps, sets, rest, exercise form, workout structure, rep speed, macronutrient diet ratios, meal frequency, etc), but the first step for anyone who wishes to escape the supplement trap and build muscle using only natural, safe methods is to learn from someone who has already achieved this exact goal, as opposed to relying on instructions from a trainer who is using steroids or relies on various bodybuilding supplements in his or her own routine.
Unfortunately, most bodybuilders who achieve impressive muscle gains are on steroids, so they never had to learn how to properly manipulate their own natural hormone levels through diet, or how to cycle weight lifting volume in a way that promotes proper recovery for someone who has no artificial chemical assistance. They then mistakenly feel as if the routine they use is adaptable to someone who wishes to avoid the same bad habits, but in reality, anybody who wishes to maximize his or her own natural genetic potential does not train or eat like a steroid lifter.
So, step one in an effort to build muscle without supplements is finding a trainer who does not rely on steroids for his or her own progress, and who has opted to avoid any supplement that claims to enhance muscle growth, so that you can benefit from the experience of someone who has learned how to produce the best possible natural progress using diet and weight training alone, without any artificial or potentially harmful aids.