Scientifically explaining the differences.

To understand the basic difference between the choice of steroids for bulk and cutting, a deeper analysis of the effects of these drugs on adipose tissue and skeletal muscle is needed, especially at the level of androgen and estrogen receptors.

Sex steroids (androgens, estrogens, progesterone) have direct activity in adipose tissue (fat) through their receptors, and variations of these hormones in men and women can lead to fat gain or loss, especially abdominal. Many androgenic steroids are known in bodybuilding for their power to increase fat burning, such as oxandrolone [1], trenbolone, primobolan, stanozolol, masteron, testosterone.

Other steroids are not as well known for increasing fat loss, possibly because they are also known to elevate estrogen levels, directly by aromatizing (nadrolone, dianabol), or indirectly by potentiating estrogenic effects (hemogenin). Still, these steroids can lead to fat loss indirectly, by increasing basal metabolism, resulting from the effect of androgenic steroids on protein anabolism, increasing the amount of proteins - especially enzymes - and thus increasing the activity of all cells [two]. Anyway, this effect of increasing the metabolic rate on fat loss of these steroids will be mitigated by an increase in the caloric balance (since they are used preferably in bulk) and also by increasing levels of estradiol (the most biologically potent estrogen).

“Sex steroid hormones are involved in the metabolism, accumulation and distribution of adipose tissue. It is now known that estrogen receptor, progesterone receptor and androgen receptor exist in adipose tissue, so their actions could be direct. Sex steroid hormones play their role in adipose tissue by genomic (activity in the cell nucleus) and non-genomic (cytoplasm) mechanisms. In the genomic mechanism, the steroid binds to its receptor and the steroid-receptor complex regulates the transcription of certain genes. Leptin and lipoprotein lipase are two key proteins in adipose tissue that are regulated by transcriptional control with sex steroid hormones [3]”.

Older and/or obese men have reduced levels of testosterone (T), and higher levels of estradiol (E2). This reduction in the T/E2 ratio enhances fat gain (especially abdominal), in addition to the possible loss of lean mass with age. Estradiol levels are highly significantly positively related to body fat mass and, more specifically, subcutaneous abdominal fat, but not visceral (omental) fat. In fact, aromatase activity in visceral fat is only a tenth of the activity in gluteal fat [4]. Not only the reduction in the T/E2 ratio, but the increase in estradiol itself can negatively interfere with fat burning, especially in individuals with a higher percentage of fat, more sensitive to estrogen and more resistant to insulin [5]. This happens due to the increased conversion of these hormones to estrogen in the adipose tissue, and due to competition in the receptors between estrogen and androgen.

Aromatase P450 activity in adipose tissue is important for the production of estrogens… Androgens and active estrogens produced locally in peripheral tissues, especially adipose tissue, may have a paracrine (local) action, interacting with the corresponding receptors on the same or cells near where its synthesis occurred before its release to the extracellular environment as such or inactive metabolites [6].

One study showed that treatment with estradiol in human breast cancer cell cultures led to down-regulation of androgen receptors [7]. This would consequently lead to a decrease in lipolytic activity in the adipose tissue of steroids that increase and/or potentiate the effects of estrogen, such as nandrolone, dianabol and hemogenin. On the other hand, the reduction in estradiol levels can potentiate the action of androgens, allowing androgen receptor levels to rise, increasing the lipolytic effect of steroids on adipose tissue. It is also important to remember that steroids such as testosterone and boldenone also undergo aromatization, but are used in cutting/contest cycles, boldenone because it suffers weak aromatization, and testosterone because it has a strong anabolic effect and good effect on fat burning [8], in addition for other reasons, such as increasing libido and disposition.

A study using Dihydrotestosterone (DHT) in rat breast cancer showed that DHT competes with estradiol for binding to the cytosolic estrogen receptor (located in the cell cytoplasm) in the rat breast. Thus, the anti-estrogenic effect of androgens on mouse breast cancer may be the result of effects of dihydrotestosterone on the estrogen receptor. If so, DHT performs one of its main actions independent of the androgen receptor [9]. This explains why non-aromatized steroids can be powerful during a diet aimed at fat loss (cutting/contest). It is important to say that steroids such as Masteron, a derivative of DHT, showed efficiency in studies on breast cancer [10]. Primobolan, another DHT derivative, is a drug similar to masteron with good anti-estrogenic properties and good thermogenic power [11]. In addition to these two drugs, other DHT derivatives like stanozolol, oxandrolone are known as good drugs to be used in cycles aimed at fat loss. Keeping in mind that being derived from DHT is no guarantee of good fat burning power for a steroid. Hemogenin, for example, is a derivative of DHT. Trenbolone is another steroid that is not derived from DHT (it is 19-nor), but it is known among bodybuilders as the best androgenic steroid for burning fat, possibly because it is the most androgenic steroid with the greatest affinity to androgen receptors, and also not undergo aromatization.

As we have seen, the choice of different steroids in diets aimed at gaining muscle volume (bulk) and fat loss (cutting) depends on the activity of these drugs in the adipose tissue and also at the cellular level, through competition between androgens and estrogens for one of the receptors. others. It is also important to remember that the effects of steroids can vary greatly from person to person, due to different hormonal and metabolic responses [5].

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