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. 
Drugs such as Nolvedex bind to the oestrogen receptors , therefore reducing the effects of the heightened oestrogen in the body. Such drugs do nothing to reduce the amount of oestrogen in the body; they merely reduce its effects via competition for the receptors . If the user wishes to reduce the amount of oestrogen they should look to drugs such as proviron and anastrozole , which are known as anti-aromatases - . they lower the conversion of the steroid to oestrogen and therefore reduces the overall amount of oestrogen present.
So just because some people look as though they have only 3% body fat does not automatically mean they are loaded on PEDs. It could mean they have found something that works for them and makes them extremely efficient at using the hormones produced in their own bodies. And there is even more going on to getting strong than what I mentioned here in this article. We didn’t take into account diet, supplementation , or health history. There is a lot going on biologically when it comes to cell growth than what we can see from the outside.