
Originally Posted by
SneakerSeven
You need them. Think of it in this simplified way- your body tries to equalize levels of est and test. You start taking something, your body stops making test because you have so much of it in your system already. Your body may also raise est levels to compensate. When you're done, you're suddenly very low on test because your body isn't making much, and you suddenly have much more est in comparison. So although the drug itself doesn't convert, it's your body's natural checks and balances that are a little out of whack, thus the need for PCT, to get things back to normal.