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What can modify a woman's physiology

Having looked at in the last few blogs at the normal menstrual cycle in detail in terms of the major hormonal changes that occur and how it affects a women's physiology, Let's now look at some commonly experienced situations that will change a woman's physiology from that of the normal menstrual cycle.

We now know the three primary hormones which impact on a woman's overall physiology are estrogen, progesterone and testosterone. Each has its own distinct effects and, when one or the other is relatively dominant in a woman's body, it generally results in a fairly similar physiology. So regardless of the specific hormonal modifier present, two women with an estrogen-like, progesterone- like or androgen-like physiology will be considered to have a similar physiology.


While there is no truly "normal' menstrual cycle, in that the variation between two women (or within the same woman) can be extremely large, it is still possible for the cycle to become extremely disrupted. While there are less severe disruptions I will mainly focus on amenorrhea and oligomenorrhea here.

Amenorrhea refers to the absence of a menstrual cycle and is defined clinically as a lack of menstruation for 90 days or more with less than three total cycles in a year (some women will not menstruate for extended lengths of time). Strictly speaking, amenorrhea can occur under many different situations. This can include a woman who has begun to menstruate at all (called primary amenorrhea), pregnancy (where menstruation stops due to not being needed) and birth control (which deliberately shuts off the normal cycle although some bleeding may still occur). There can be numerous medical causes for amenorrhea but none of these represent the type of amenorrhea that I will discus in this blog.

Rather, I will focus only on Functional Hypothalamic Amenorrhea (FHA). As the name suggests, FHA originates in the hypothalamus, which will shut down the menstrual cycle under certain circumstances. These tend to be stress related including the stress of dieting, the stress of exercise, mental stress or some combination of the three. Physiologically, in amenorrhea, estrogen drops to about 33% of normal levels and progesterone drops to roughly 10% of normal. The normal cyclical changes are also lost and hormonal levels of both are effectively a flat line. The release of LH and FSH, which I described briefly in the last blog, also disappears such that the follicle never matures or implants, the corpus luteum doesn't develop and there is no uterine lining to shed (hence the lack of bleeding). When amenorrhea develops, a woman's physiology changes enormously.


Oligomenorrhea refers to an infrequent or delayed menstrual cycle and is defined clinically as a cycle that only occurs every 35-90 days (recall that the normal menstrual cycle occurs within 24-32 days). In contrast to amenorrhea where a woman's primary hormones drop to low levels and show no cyclical changes, in oligomenorrhea those hormones are lowered but are still changing. On some days hormone levels may be identical to the normal menstrual cycle but on others their levels will be random. Like amenorrhea, oligomenorrhea can occur for many reasons.

This includes some types of birth control (where light bleeding may occur) and a variety of medical conditions (including PCOS, discussed below).

There are two types of oligomenorrhea. The first is part of the continuum of adaptations to dieting that can lead to amenorrhea. While all women were originally thought to have this type of oligomenorrhea although it's now known that there is a subgroup of women who are oligomenorrheic due to elevated androgen/testosterone levels.


In the last blog, I mentioned that the term androgen is sort of a catch-all for a variety of hormones that are produced in the body including testosterone, DHEA, DHEA-sulfate and a few others but I'll continue to use the term androgen or testosterone generally throughout these blogs. When those levels are elevated above normal, this is referred to as hyperandrogenism. Here I am combining two slightly different hormonal situations which are absolute and relative hyperandrogenism. Absolute hyperandrogenism will refer to any situation where a woman's testosterone levels are elevated above normal. Relative hyperandrogenism will refer to a situation where testosterone levels are not elevated above normal but estrogen and progesterone levels have decreased so that androgens are relatively higher.

Here we are only going to look at absolute hyperandrogenism, when a woman's testosterone levels are elevated above their normally low level along with the implications that has. Given the effects of testosterone, overall the effect of absolutely hyperandrogenism is some degree of masculinization or virilization of a woman's body with an increased prevalence of male secondary sexual characteristics along with other potentially negative effects. This includes increased body and facial hair, oily skin, acne and an increased risk of hair loss. Hyperandrogenic women often have a more "male" like body in that they have narrower hips and tend to carry relatively more of their body fat around their midsection. Relevant to this blog, women with elevated testosterone levels often show an increased amount of muscle mass along with potentially improved sports performance and an ability to respond to training.

Probably the most common cause of elevated testosterone in women, and the one I suspect most readers are at least passingly familiar with, is Poly-Cystic Ovary Syndrome or PCOS. PCOS has been found in somewhere between 6-20% of women and one of the most common effects is either oligomenorrhea, amenorrhea or infertility (due to a lack of an egg being released). In fact, roughly 15-20% of women who are infertile are diagnosed as having PCOS. PCOS is often associated with weight gain and obesity with more fat being carried around the midsection. Here even small amounts of weight loss (5-10% of current body weight) drastically improve health markers and fertility. Interestingly, while PCOS women often report having trouble losing weight, research shows no difference in weight loss between PCOS and non-PCOS women, at least within tightly controlled research.

PCOS is clinically diagnosed according to the Rotterdam criteria and requires that two of the following three symptoms be present: multiple cysts on the ovaries, clinical or biochemical signs of hyperandrogenism, and either oligomenorrhea or anovulation (an egg is not released). Practically this means that there are four distinct types of PCOS. A woman could have all three symptoms or any combination of two symptoms (i.e. cysts+hyperandrogenism, cysts+oligomenorrhea/anovulation, or hyperandrogenism+oligomenorrhea/anovulation). When hyperandrogenism is present (and this will usually manifest with oily skin, acne, central fat distribution or hair loss), the PCOS woman's testosterone levels may be 2.5-3 times a woman's normal levels. While this is still well below even the low normal range in males, women's greater sensitivity to androgens means that this will have a profound effect on her overall physiology. PCOS women also have lower levels of Sex-hormone Binding Globulin (SHBG) which results in more free testosterone (the biologically active type) being available.

Perhaps the most commonly seen metabolic dysfunction in PCOS is insulin resistance, an inability of the body to properly respond to insulin. Not only does this have numerous health consequences, it acts to maintain elevated androgen levels as elevated levels of insulin affect adrenal metabolism so that it produces even more androgens. This is even more true if excessive amounts of refined carbohydrates are being consumed but this turns into a vicious cycle where the elevated androgens cause insulin resistance which increases the insulin response which increases androgen levels.

Insulin resistance is extremely prevalent in PCOS and is estimated to occur in 60-80% of women with PCOS. This may increase to 95% if obesity (especially fat around the midsection, called central obesity) is present. The impact of obesity appears to be significant as lean women with PCOS show relatively normal insulin sensitivity along with other physiological differences. Regular activity in overweight women also improves insulin sensitivity although it is still impaired compared to lean/normal weight PCOS women. While I don't intend to cover every possible medical situation a woman might encounter, I do want to mention that women with PCOS are also 3 times more likely to suffer from thyroid disease (especially Hashimoto's thyroiditis) than non- PCOS women . This adds up to a particularly problematic condition.

This second situation where a woman might show elevated testosterone levels is currently referred to as subclinical hyperandrogenism, representing a situation where testosterone levels are 20-30% above normal. While smaller than in PCOS, this is enough to have physiological effects without the clinical health issues of PCOS. Finally is an extreme rare condition (occurring in 1 in 12,000-18,000 people) called congenital adrenal hyperplasia (CAH, which can also occur in males). For complicated reasons, individuals with CAH produce adrenal androgens at an enormously elevated level. In both females and males, this causes an early puberty, extreme masculinization (including an enlarged clitoris or penis) and infertility. Since it is so rare, I won't discuss it further.

Even when oligomenorrhea was thought to be related to amenorrhea, it was often found that the oligomenorrhea seen in female athletes was accompanied by elevated testosterone levels. This was assumed to be a consequence of the changes in estrogen and progesterone but this is actually reversed and it is the elevated testosterone levels causing both oligomenorrhea and the changes in hormones such as estrogen and progesterone that occur. In athletes, the elevated testosterone seen in this type of oligomenorrhea appears to be directly for the improvement in performance that is seen. The effects of testosterone such as increased muscle mass, bone density, the ability to respond to training and even aggressiveness can be beneficial for many sports which would explain its high prevalence. Subclinical hyperandrogenism was first identified in swimming, a sport requiring strength and power with less of an emphasis on leanness, although up to 30% of female runners have been found to have elevated testosterone levels as well.

Women with this type of testosterone caused oligomenorrhea are likely to show an enhanced response to training regardless of sport. Supporting this is the fact that both PCOS and hyperandrogenism (along with menstrual cycle dysfunction) is found in female Olympic athletes


As I mentioned above, it's not uncommon to see women with elevated testosterone levels, to have a different body structure than women without elevated testosterone levels. Narrower hips, what researchers call a linear body type (meaning less curves), are one example and these types of changes can make women relatively more or less suited to succeed at certain types of sports. This is in addition to any other benefits that even slightly elevated testosterone levels have in terms of trainability mentioned above.

In all three cases of elevated testosterone in women, there is a continuum of effects in terms of the masculinization/virilization and other effects which may occur. CAH is the most profound with PCOS related hyperandrogenism the next and subclinical hyperandrogenism the least. In both PCOS and subclinical hyperandrogenism, it's common to find some degree of increased male sexual characteristics (i.e. the sub-clinically hyperandrogenic woman may carry relative more fat on her stomach) and this is often the first indication that androgens are elevated relative to normal. Oligomenorrhea or outright amenorrhea may be present but, distinguishing it from FHA, this will have been present from a fairly early point in a woman's life as it is related to her baseline level of testosterone in the first place.

For women interested in sports performance, hyperandrogenism can have enormous benefits, improving the ability to build muscle mass, strength, power and endurance. But this frequently comes with the consequence of increased body hair, acne, etc. along with the potential of infertility (important to those women who want to become pregnant). For inactive or relatively fatter women, the androgen-like physiology and the insulin resistance it tends to cause will generate a luteal phase physiology. For lean hyperandrogenic females who are highly active, insulin sensitivity should be relatively normal and an effective follicular phase physiology can be assumed to be present.

Since women with PCOS/hyperandrogenism may have distinctly different goals (i.e. performance vs. improved health/fertility), I will discuss them somewhat separately when I talk about diet and supplement recommendations later in the blogs. I'd note again that even small amounts of weight/fat loss can drastically improve health in women with overt PCOS. At the extremes, this may be insufficient and more pharmaceutical strategies may be required. Many approaches are used here with Metformin being a primary one. Hormonal birth control, which doesn't improve fertility but does improve many health parameters, is also commonly used and is discussed in detail below.

On the next blog we will look into the different types of Birth Control and how they work.

Coach HB

The above information is taken from the The Woman's Book by Lyle Mcdonald with Eric Elms

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