Because lowering estrogen doesn't always help with fat loss and can even get in the way!

I've previously commented that I consider it a bad idea to lower estradiol in women who use steroids, mainly because it enhances the virilizing effects of androgenic steroids. I've seen many athletes and regular users who used an aromatase inhibitor during the cycle because they believed that lower estrogen would facilitate fat loss.

Things aren't quite that simple, post-menopausal (thus low estrogen) women accumulate more fat in their intra-abdominal stores than pre-menopausal women and we know that estrogen is responsible for the larger gluteal fat deposits -femoral in woman. Calm down, I'm not saying that high estradiol is good, but that lowering/suppressing estrogen can be a problem, especially in women.

The pear-shaped female body pattern is due to the greater presence of estrogen receptors in the buttocks and thighs, as well as the greater presence of alpha-adrenergic (anti-lipolytic) receptors in relation to beta-adrenergic (lipolytic) receptors , which favors greater accumulation of fat in this region. Women's lower limbs have been found to have about nine times more alpha-2 receptors compared to beta-2 receptors. This means less fat burning for women in the lower limbs.

Obese men have greater expression of the aromatase enzyme, so they convert more testosterone into estradiol, which causes negative feedback from the hypothalamic-pituitary-gonadal axis, reducing testosterone levels and increasing insulin resistance. In these men, testosterone replacement therapy improves insulin sensitivity and body composition. Elevated estrogen also increases insulin resistance in men and women (during pregnancy for example).

Estrogen can also affect food intake and body weight through its interaction with neuropeptides that act on hunger and satiety centers in the hypothalamus.

“Gonadal hormones potently control food intake and body weight. In female animals, the activation effects of estradiol acutely and chronically influence body weight homeostasis [1-3]. In rats and mice, estrogen exerts a tonic inhibitory effect on meal size and daily food intake throughout the ovarian cycle and a cyclic inhibitory effect during the peri-ovulatory phase [1, 3-5]. Estrogen removal leads to changes in meal size and duration [6,7], hyperphagia and obesity. Estrogen has similar effects in humans where it modulates peri-ovulatory decreases in daily food intake [8]. Furthermore, estrogen reductions are associated with changes in body weight and fat distribution in humans, which parallels the findings in animals [8]. Estrogen has the ability to control energy balance, food intake and body fat distribution and this can be mediated through its interaction with orexigenic and anorexigenic hormones.”

Low estrogen levels increase the prevalence of insulin resistance, especially in women. Visceral fat varies inversely with estrogen levels. When estrogen levels become low enough visceral fat accumulation occurs in females, possibly due to direct estrogen effects. In women with polycystic ovary syndrome, insulin resistance is associated with hyperandrogenism and with improved insulin sensitivity there is a reduction in testosterone levels (use of metformin, for example). Lowering testosterone with an oral contraceptive or antiandrogen (spironolactone) also improves a woman's insulin sensitivity.

So you understand why many women can have increased fat and water retention with the use of androgenic steroids (the opposite effect than they expected) and this can worsen with the use of aromatase inhibitors. That's because many coaches and athletes believe that estrogen hinders fat loss, but as we've seen it's not the case if it's at physiological levels. I have also commented in other texts that the use of contraceptives (especially those that combine estrogen with progesterone) impair fat loss and muscle mass gain, because they drastically reduce testosterone levels, especially free testosterone.

We already know that in men, estrogen suppression can negatively affect the lipid profile and sexual function (libido and erection). A high level of estrogen can impair fat loss, especially in individuals who are less sensitive to insulin. In athletes who are easy to lose fat, a drastic reduction in estrogen is unlikely to improve fat loss, and this is much less likely in women, where the opposite effect is more likely to occur.

Subcutaneous adipose tissue has higher concentrations of estrogen (ER) and progesterone (PR) receptors; However, visceral adipose tissue has higher concentrations of androgen receptors (AR). In addition, subcutaneous adipose tissue has few androgen receptors, and estrogen down-regulates AR expression in subcutaneous fat. Androgens and estrogens down-regulate each other's receptors, but when the level of androgens is high (on a steroid cycle) estrogen is unlikely to interfere negatively in individuals who have low fat percentage and good insulin sensitivity. For those with a higher percentage of fat and/or those who have a lot of difficulty in losing fat, greater estradiol control is prudent, although not aggressively suppressing it. In women, lowering estradiol can be as harmful as using contraceptives.


Central Effects of Estradiol in the Regulation of Adiposity
LM Brown and DJ Clegg

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