Our sport has reached a dangerous crossroad, where it seems that too many athletes (pro and amateur) have become walking time bombs, with the prospect of a future lived in poor health (or worse) being the only trophy they can look forward to. Consider the following lifestyle: use liberal amounts of steroids, growth hormone and insulin; kick in an array of exotic substances for God knows what; add huge quantities of food every two hours that severely overtax the human digestive system; throw in a heavy dose of painkillers (some narcotic in nature); adopt an MO that requires dropping 40 or 50 pounds twice a year in a 12-week period; peak on contest day by means of diuretics so as to be bone dry and severely dehydrated. We don’t have to fund a Harvard research project to figure out that such a regimen is a recipe for physical disaster.
This is a great question that, unfortunately, cannot be answered in just a couple hundred words. There are important issues that focus on educating one's self prior to embarking on such a course of action, particularly the downsides of using steroids – the side effects, the proliferation of fake gear, getting off of them, getting blood work done, etc. And, the fact that buying, selling and transporting them is (in America) still a felony, not to mention banned by all sports federations. All very important salient issues that require a lot of space to do justice.
Frank Zane shouldn’t be the standard which we use as a “cut off” to tell whether or not an athlete is natural. While he was on roids and fairly impressive, at 5’9, 185 lbs, 5% bodyfat, he only had an FFMI of around 26. While this is high, easily over the broscience “limit” of 25, several known natural bodybuilders in early bodybuilding history have surpassed it, with Jack Delinger hitting an FFMI over 28 in 1949 and George Eifferman hitting around in 1948. These and other high numbers were obtained before steroids were even available to the public, before Russians even gave steroids to their Olympic team. Likewise, these were before leg development was emphasized in bodybuilding to the degree it is now, so these people may have been able to attain higher levels of physical development than even then. Now, your current numbers list Lazar at 200 pounds at 5’9 and 5% bodyfat. This would put him at an FFMI of around 28, which is hard to achieve, but believable because of the above examples. However, other sources, such as SimplyShredded and HealthyCeleb put him at 5’11” and 195 lbs, which at a bodyfat percentage of 5%, would put him at an FFMI of – which is well under previous natural achievements. At the end of the day, he may be natural, even though it is way easier for him to be where he is with the help of steroids.