Perimenopause Naturopath & Nutritionist · Australia WideRoot-Cause Support for Perimenopause.

Progesterone drops first

Progesterone is the first hormone to decline in perimenopause, usually in your late 30s or early 40s. It is the calming hormone, the one that keeps your nervous system steady, supports your sleep, and balances the more stimulating effects of oestrogen. Progesterone also supports your GABA pathway, which is the brain's main calming system. Think of GABA as the handbrake on your nervous system. Pull it up and everything settles.

When progesterone drops, you lose some of that handbrake support, and your system becomes more reactive, more anxious, and less able to stay asleep through the night.

This is why sleep is one of the first things to change for many women in perimenopause.

You might have been someone who always slept well, and now you are waking at 2am wired, heart racing, mind switching on, and it takes you two hours to get back to sleep. That is not random. That is your nervous system without its handbrake.

Progesterone is also the hormone that balances oestrogen through the second half of your cycle. When progesterone drops, oestrogen is unopposed for longer, which is where heavy bleeds, breast tenderness, fluid retention, and PMS that feels disproportionate start coming from.

I see this in clinic constantly in women in their late 30s and early 40s who have been told they are "too young for perimenopause."

The bloods often look fine because standard tests are not picking up what is happening across the cycle, and the symptoms themselves are the most useful clinical information at this stage.

Oestrogen doesn't decline smoothly, it swings

Oestrogen does not go down in a clean line through perimenopause. It swings. High, then low, sometimes within the same week. And each end of that swing produces a different set of symptoms, which is why you can feel like you are losing your mind in the same cycle that you feel bloated and premenstrual for 14 days.

The highs cause breast pain, migraines, heavy bleeds, bloating, and emotional reactivity. The lows cause hot flushes, brain fog, joint pain, anxiety, and vaginal dryness. A single oestrogen blood test captures one moment in that rollercoaster, which is why so many women come to me with a stack of "normal" results and symptoms that are very clearly not normal. This is where functional testing earns its keep. I use DUTCH Complete and DUTCH Cycle Mapping to look at how you are producing, using, and clearing your oestrogen across a full cycle, because that is the information that standard pathology simply does not collect.

Your gut microbiome plays a direct role in oestrogen balance

Your gut contains a specific group of bacteria called the oestrobolome, and its job is to process used oestrogen so your body can excrete it through the bowel.

When your oestrobolome is healthy and your gut is functioning well, oestrogen that has done its job is packaged up, sent out, and that is the end of it.

When the gut is inflamed, dysbiotic (too much of the wrong bacteria, not enough of the right ones), or moving too slowly, the packaged oestrogen gets unpackaged and reabsorbed back into circulation.

The same hormone circulates around your body a second and third time, adding to the oestrogen load that should have left days ago.

This is one of the reasons so many women develop new gut symptoms (bloating, reflux, constipation) at exactly the same time as their hormone symptoms get worse. It is not two separate problems. It is the same problem showing up in two systems. If the gut is not addressed, hormone support will only get you partway there. Fixing the gut in perimenopause is a hormonal intervention, not just a digestive one.

The pregnenolone steal (why stress exacerbates the symptoms)

The mechanism most women never hear about is the pregnenolone steal, and it is one of the most clinically important to understand.

Progesterone and cortisol (your main stress hormone) are both made from the same raw material in your body, a precursor called pregnenolone.

Under chronic stress, your body prioritises survival over reproduction every time, so more of that raw material gets diverted into making cortisol, and less is available for progesterone production.

This is called the pregnenolone steal, and it is one of the fastest accelerators of perimenopausal symptoms I see in clinic.

On top of that, elevated cortisol raises blood sugar, worsens insulin sensitivity, promotes belly fat storage (particularly the visceral fat around your organs), disrupts sleep, and inflames the gut lining. Every single one of those things then feeds back into every other perimenopause symptom.

This is why the "eat less, move more" advice fails so many women at this stage. If your cortisol is chronically elevated and your nervous system is dysregulated, your body is not in a state where weight will shift or sleep will improve, no matter how clean the food is or how hard you train.

Nervous system regulation is one of the central parts of a clinical perimenopause plan, because cortisol regulation directly affects progesterone production, sleep quality, insulin sensitivity, and gut function, and until cortisol comes down the rest of the protocol can only do so much. Everything else works better when it is balanced.

Thyroid overlap (and why standard testing usually misses it)

Perimenopause and thyroid dysfunction look almost identical on paper: fatigue, weight gain, hair loss, mood changes, cold hands, constipation, brain fog. This is not a coincidence.

The hormonal shifts of perimenopause affect thyroid function directly, and autoimmune thyroid conditions like Hashimoto's very commonly present for the first time in a woman's late 30s or 40s.

The two often run side by side.

The problem is that standard thyroid testing in Australia usually stops at TSH.

TSH alone is not enough, and I see this missed constantly. Your TSH can be sitting in the "normal" range while your free T3 is too low, your reverse T3 is too high, your antibodies are flagging early autoimmune activity, and your body is struggling significantly to convert and use thyroid hormone.

Thyroid panels are recommended for the women I work with in perimenopause: TSH, free T3, free T4, reverse T3, TPO antibodies, and thyroglobulin antibodies.

Without the full picture, you will spend years chasing symptoms that are half hormonal and half thyroid, and getting partial results.

Insulin sensitivity starts slipping (and this is why belly weight won't budge)

Oestrogen plays a protective role in how well your body responds to insulin.

When oestrogen is healthy and stable, your cells open the door to insulin easily, glucose moves out of your bloodstream efficiently, and your metabolism runs well. As oestrogen starts fluctuating and declining in perimenopause, that protective effect weakens.

Your cells become less responsive, your pancreas compensates by producing more insulin, and elevated insulin promotes fat storage in a very specific pattern: belly, waist, upper body, and arms. These areas have more insulin receptors than fat cells elsewhere, which makes them more responsive to the storage signal.

I see this in clinic every week. Women who are eating well, training consistently, doing everything they have been told to do, and the weight around their middle will not move. The hormonal environment (elevated insulin, often combined with elevated cortisol) will not permit fat release until those levels come down. This is a biochemical problem, and no amount of willpower or calorie-cutting will override it while those hormones are running the show.

The good news is that insulin sensitivity is one of the fastest systems to respond to dietary change.

A specific nutrition approach (protein at every meal, plenty of vegetables, smaller intentional amounts of carbohydrates, meals spaced 4 to 5 hours apart) combined with strength training starts shifting insulin sensitivity within weeks. It is usually the first piece that starts to move once we get the full plan in place.