Testosterone, Cortisol and Thyroid Hormone

Okay, let's have a look at some more key hormones, and one of them is testosterone. We mentioned this earlier when we talked about the menstrual cycle. Testosterone tends to peak around ovulation, and it’s the hormone of action and motivation. You might have heard testosterone associated mostly with men, and to be honest, it is their main hormone — testosterone is to men what progesterone is to women. But we need it too. It motivates us, fuels our drive, and supports our confidence. Around ovulation, when everything is gearing up for fertility, testosterone gives us that spark to take action — it boosts energy, confidence, and libido. So you may feel a higher sex drive around ovulation — that’s testosterone (with a little help from estrogen). Testosterone also helps us build muscle and maintain bone health. As we age, testosterone levels tend to decline, which can lead to reduced motivation, libido, and even brain fog or muscle and bone loss — especially if we’re not supporting muscle and bone strength through movement and nutrition. It’s important to remember that testosterone is not just a male hormone. We actually make estrogen from testosterone through an enzyme called aromatase, which is present in our fat tissue. High fat levels can lead to higher aromatase activity, converting more testosterone into estrogen — which may create hormonal imbalances. So think of testosterone as your hormone of action and motivation. It supports energy, drive, muscle, bone health, and mental sharpness. Then we have cortisol — a really important hormone to understand. You’ve probably heard of cortisol referred to as the “stress hormone,” but in truth, it’s our anti-stress hormone. Cortisol is what helps the body respond to challenges. It’s released when the body perceives stress or danger, and its role is to help us cope, not harm us. The problem isn’t cortisol itself — it’s when cortisol is constantly being activated. Cortisol is made in the adrenal glands, the same place where progesterone is made, and the body can convert progesterone into cortisol when needed. It gives us morning energy — that natural “get up and go” — following the rhythm of the sun. It helps us face the day, maintain alertness, and regulate blood sugar. One of cortisol’s key roles is to keep blood sugar stable. When our blood sugar drops — between meals, after exercise, or during long gaps without food — the body releases adrenaline and cortisol to bring it back up. Cortisol helps the liver produce and release glucose into the bloodstream to restore balance. It also works with adrenaline to keep us alert and focused — it’s part of our survival system. But here’s the key: if the body must choose between survival and reproduction, it will always choose survival. That means cortisol will be prioritized over progesterone. Chronic stress or constantly elevated cortisol can therefore suppress progesterone and disturb the estrogen-progesterone balance, leading to symptoms like anxiety, poor sleep, and irregular cycles. Cortisol also impacts immunity, digestion, and reproduction. When we’re in “fight or flight” mode, the body doesn’t prioritize these functions — it’s focused on survival. This is why chronic stress can lead to weaker immunity, poor digestion, or hormonal imbalances. Over time, if cortisol production remains high for too long, the adrenals can become depleted, leading to low cortisol levels — what we often refer to as burnout or adrenal fatigue. That’s when you might feel constantly exhausted, foggy, or unable to handle stress. So while cortisol is essential, it’s equally important to allow for rest, recovery, and balance so it doesn’t dominate our system. Finally, let’s talk about another crucial hormone — not directly part of the menstrual cycle but deeply connected to our overall hormonal health — and that’s the thyroid hormone. The thyroid gland sits at the front of your neck, shaped like a small butterfly. It’s your body’s thermostat — the master regulator of metabolism, energy, and temperature. When the thyroid functions well, everything in the body tends to run smoothly. But when thyroid function slows down, everything slows down. If thyroid activity is low, you may feel cold, have cold hands and feet, low energy, or notice dry skin and hair loss. You may also experience slower digestion, bloating, or constipation because everything — including your gut motility — slows down. Thyroid health is also deeply linked to your hormonal balance. Low thyroid function can impact estrogen and progesterone ratios. We make our sex hormones from cholesterol, but thyroid hormone is needed to convert cholesterol into pregnenolone and then into progesterone. So if thyroid activity is low, we make less progesterone, leading to more estrogen dominance. It also works the other way around — too much estrogen can block the conversion of thyroid hormone from its inactive form (T4) to its active form (T3), a process that normally happens in the liver. This creates a vicious cycle: low thyroid function lowers progesterone, which increases estrogen dominance, which further slows down thyroid conversion. The thyroid is also sensitive to stress. Chronic activation of cortisol suppresses thyroid function, slowing metabolism and leading to fatigue, mood changes, hair and skin issues, digestive problems, and further hormonal imbalance. As you can see, all these hormones — testosterone, cortisol, and thyroid — are interconnected. When one goes off balance, it often affects the others. Understanding this web of connection helps us see why stress, nutrition, rest, and emotional wellbeing all play such a major role in hormonal health. In the next module, we’ll explore what drives these hormonal imbalances — and, more importantly, what we can do to support our system to come back into balance.