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.
Natural bodybuilding is a bodybuilding movement with various competitions that take place for bodybuilders who abstain from performance-enhancing drugs . This categorically excludes the use of substances like anabolic steroids , insulin , diuretics and human growth hormone .  If a bodybuilder meets the requirements of the sanctioning body (the recognized group or authority that sanctions and validates competitions) that they are competing in, then they are considered to be "natural". There are numerous sanctioning bodies who provide their own rules and regulations that govern the competition procedures, event qualifications, banned substance lists, and drug testing methods. Doping detection methods include urinalysis and polygraph testing, and federations typically conduct these tests on the day of competition, or shortly before. Out-of-season testing, although less common, may also be used. Each organization will specify within its rules the length of time that its athletes should be drug-free, which may vary from testing clean on the day of the event, to being drug-free for a number of years, right up to a lifetime natural requirement.
Steroid isolation , depending on context, is the isolation of chemical matter required for chemical structure elucidation, derivitzation or degradation chemistry, biological testing, and other research needs (generally milligrams to grams, but often more  or the isolation of "analytical quantities" of the substance of interest (where the focus is on identifying and quantifying the substance (for example, in biological tissue or fluid). The amount isolated depends on the analytical method, but is generally less than one microgram.  [ page needed ] The methods of isolation to achieve the two scales of product are distinct, but include extraction , precipitation, adsorption , chromatography , and crystallization . In both cases, the isolated substance is purified to chemical homogeneity; combined separation and analytical methods, such as LC-MS , are chosen to be "orthogonal"—achieving their separations based on distinct modes of interaction between substance and isolating matrix—to detect a single species in the pure sample. Structure determination refers to the methods to determine the chemical structure of an isolated pure steroid, using an evolving array of chemical and physical methods which have included NMR and small-molecule crystallography .  :10–19 Methods of analysis overlap both of the above areas, emphasizing analytical methods to determining if a steroid is present in a mixture and determining its quantity.