Deca (and tren) are progestins.. i would run caber with both. and i would run an AI with deca.. no AI necessary with just tren.. gotta cover all bases. can you get away with not running it? yup.. is it adviseable? nope. just like taking your life savings and putting it in a slot machine isn't adviseable either.. we all have a friend who ran deca with no ancillaries and claims that all went well
here is a writeup that you should read.. i didn't write the following but it will help you better understand what you are asking.
Progesterone : Its not so much progesterone that we watch, which is actually a healthy hormone, but progestins which may act upon its receptors. Progestins, like Tren or Deca (nor-9's), may act on its receptor or lower progesterone in the blood. Gyno and lactating are more common side effects. Some people use progesterone receptor blockers to combat this, or a prolactin production inhibitor.
FYI:
Progesterone — influences the growth in size of alveoli and lobes. Progesterone levels drop after birth. This triggers the onset of copious milk production.
Prolactin — contributes to the increased growth of the alveoli during pregnancy.
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Role of Progesterone in causing gyno:
Progesterone is found in both males and females. It is a precursor to many important hormones in men and women. In women it plays a role in pregnancy and in breast growth. In men, excessive progesterone can stimulate breast growth, like it does with women. While Estrogen is normally the cause of gynecomastia under normal physiological conditions, Tren and other similiar steroids stimulate the progesterone receptors because they are not only anabolic steroids, but also of a class called progestins. Progestins are the synthetic forms of steroids structurally similiar to progesterone, that have the ability to bind to the progesterone receptor too. Deca and Anadrol also are progestins, but they also aromotize to estrogen, unlike Tren. Some bodybuilders coin the term “progesterone gyno”, to explain gyno from progestin steroids.
Progesterone Gyno Controversy:
There is a major debate among bodybuilders on this entire topic. Some believe that progesterone causes the gyno in Tren users. Others believe it is actually prolactin, the hormone responsible for lactation and breast growth during a women’s pregnancy. This may explain why some experience lactating on tren cycles. Others believe it is a combination of estrogens and either prolactin or progesterone, working all synergistically to develop gyno.
Who is right?
Many Research studies I’ve seen, show that estrogen plays a synergistic role with progesterone, prolactin, and in gynecomastia. Although some bodybuilders say it’s the prolactin or progesterone directly causing it, there is NO studies to show gyno can develop without high levels of estrogen. Even IGF-1 and Growth hormone has been shown in studies to play a crucial synergistic role in the development of breast tissue. So I believe no matter what kind of steroid you take, lowering estrogen with anti-estrogens and avoiding stacking Tren with aromatizing steroids, is how you really prevent “Progesterone gyno”. With very low levels of circulating estrogen, it appears impossible or very difficult for progesterone gyno to develop.
Progesterone Control
Lilopristone, Onapristone: These are progesterone blockers also, said to be safer and possibly more effective than RU-486 when it comes to progesterone blocking. They were developed after RU-486 in an attempt to make more effective, less harsh drugs to block progesterone.
Dostinex (Cabergoline), Bromo (Bromocriptine), B-6 : These are used for Deca/Tren gyno sides. This type of gyno is related to progesterone and its receptors. Tren/Deca may act on the progesterone receptor, as they are progestins, and may increase prolactin in the blood (causing lactating). These drugs stop production of prolactin at the pituitary gland. Controlling estrogen levels with an AI also helps here, as progestins themsleves haven't been proven to cause gyno.
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