What Hormones Actually Are and why they Affect Almost Everything: PART 1
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Your body runs on a communication system called the endocrine system: a network of glands including the hypothalamus, pituitary, thyroid, adrenal glands, pancreas, and ovaries that produce and release chemical messengers called hormones. Those hormones travel through the bloodstream carrying instructions to cells and organs throughout the body, coordinating everything from your energy levels and mood to your cycle, metabolism, and stress response.
Most of us were never taught how this system works. We just absorbed the idea that hormones are the reason women feel things intensely and left it at that.
That's a very incomplete picture.
Hormones are chemical messengers
A gland produces a hormone, releases it into the bloodstream, and it travels to target cells that have receptors designed to receive it. When the hormone binds to its receptor, the cell gets its instructions and responds. That response might be producing another hormone, releasing glucose, slowing digestion, preparing the body for sleep, or hundreds of other things.
The glands in this system don't work independently. They're in constant conversation with each other.¹
There are many more hormones than most people realize
Most people, when they hear "hormones," think estrogen and progesterone. Those are important, and we'll get to them. But the body produces over 50 identified hormones, each with specific functions. ² They fall into a few broad categories.
Sex hormones include estrogen, progesterone, and testosterone. These are produced primarily in the ovaries and adrenal glands. They govern reproductive function, but their reach goes much further, influencing bone density, cardiovascular health, mood, cognitive function, and skin. ³ Testosterone belongs to a class of hormones called androgens. In women, androgens are present in smaller amounts than in men, but they still play a role in libido, energy, and muscle strength. When androgen levels are too high, they can contribute to symptoms like acne, hair thinning, and irregular cycles.
Adrenal hormones include cortisol and adrenaline (also called epinephrine). Produced by the adrenal glands (located on top of the kidneys), these are your stress response hormones. Cortisol regulates energy, inflammation, blood sugar, and the sleep-wake cycle. It's not inherently harmful; it's essential. The problem is what happens when it stays elevated for too long.⁴
Thyroid hormones, primarily T3 and T4, regulate metabolism, body temperature, heart rate, and energy levels. The thyroid is small but has an outsized effect on how you feel day to day. Low thyroid function is one of the most commonly underdiagnosed conditions in women. ⁵
Metabolic hormones include insulin and glucagon, produced by the pancreas. These regulate blood sugar by controlling how glucose moves in and out of cells. Insulin resistance, when cells stop responding to insulin efficiently, is increasingly common and has direct connections to hormonal imbalance. ⁶
Peptides and other hormones include melatonin (sleep regulation), oxytocin (bonding and uterine contractions), leptin and ghrelin (hunger and satiety), and growth hormone. These are less talked about but deeply relevant to how women feel across different life stages. ⁷
The system works as a whole
Here's what most hormone conversations miss: these categories don't operate in separate lanes. They're part of one interconnected system, and what happens in one area affects the others.
Cortisol and estrogen are a good example. Chronically elevated cortisol, the kind that comes from sustained stress, may suppress estrogen production and disrupt progesterone levels. ⁸ That can affect your cycle, your mood, your sleep, and your energy all at once, through one underlying mechanism.
Insulin and sex hormones are similarly connected. Elevated insulin levels may increase androgen production in the ovaries, which is one of the drivers behind conditions like PMOS, polyendocrine metabolic ovarian syndrome (formerly called PCOS).⁹
Thyroid function and estrogen also interact. Estrogen influences how thyroid hormones bind to proteins in the blood, which affects how much is actually available for your cells to use. ¹⁰
The body doesn't experience these as separate systems. A disruption in one area creates ripple effects across others. This is why hormonal symptoms are rarely simple and why addressing them well requires looking at the full picture.
Why this matters
Symptoms like fatigue, mood changes, irregular cycles, poor sleep, and brain fog are often written off as stress, aging, or just being a woman. Understanding that these symptoms may have hormonal drivers, and that those drivers are connected, is a different starting point entirely.
Part 2 of this series covers what hormonal disruption actually looks like, which hormone categories tend to be behind the most common symptoms women experience, and why one symptom often has more than one hormonal explanation.
References
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- Garber JR, et al. Clinical practice guidelines for hypothyroidism in adults. Endocr Pract. 2012;18(6):988–1028.
- Mauvais-Jarvis F, et al. The role of estrogens in control of energy balance and glucose homeostasis. Endocr Rev. 2013;34(3):309–338.
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- Santin AP, Furlanetto TW. Role of estrogen in thyroid function and growth regulation. J Thyroid Res. 2011;2011:875125.