Perimenopause explained: symptoms, hormonal changes, and how nutrition can help
Introduction
If you're in your late 30s or 40s and noticing changes in your cycle, sleep, mood, or energy that feel hard to explain, perimenopause may be the missing piece of the puzzle.
Understanding what's happening hormonally during perimenopause can be empowering. When you recognise that your symptoms are driven by real, measurable shifts in oestrogen and progesterone, you can take proactive steps to support your health.
In this guide, we'll explain what perimenopause is, how it affects your whole body, and the nutritional and lifestyle strategies that can help you feel more like yourself again.
In this article:
What is perimenopause
Perimenopause is the stage two to twelve years before menopause. It can be the time of greatest symptoms.
Menopause is the life phase that begins one year after the last period. It is usually the time of less or almost no symptoms.
Perimenopause starts when there are persistent differences in cycle length of seven or more days between consecutive cycles and continues until twelve months after the last menstrual period. This is based on The Stages of Reproductive Aging Workshop (STRAW +10) system criteria. Hormonal changes often start around a decade before periods stop.
Perimenopause unfolds in stages, and the timeline can vary significantly from woman to woman.
Very early perimenopause
This can start as early as the late 30s and typically spans two to five years. During this stage, periods may still be fairly regular, but symptoms such as anxiety, breast pain, and a general sense that something feels "off" can begin to appear. Cycles may start to vary in length by seven or more days.
The menopause transition
This stage can span around three years. Cycles start to change more noticeably — periods may be skipped, and gaps of 60 or more days without a bleed can occur. Neurological changes, mood shifts, hot flushes, sleep issues, heavy flooding, metabolic changes, and bone loss become more common during this phase.
Final menstruation
The final period can occur as late as age 54. After one year without a cycle, a woman is considered to have transitioned to menopause.
Hormonal changes, and why symptoms are often labelled as ‘normal’
Perimenopause is the second puberty. Women in their 40s can have up to 3x more oestrogen (E2) than in their 30s. Rather than a steady decline, this phase is characterised by significant hormonal fluctuation, with oestrogen levels peaking and dropping unpredictably. This volatility is one reason symptoms can feel so intense and confusing.
Cycles may become shorter in the earlier stages due to hormonal shifts. However, as ovulation becomes less consistent and progesterone declines, many women experience longer, heavier, or more irregular bleeding. Without sufficient progesterone to regulate oestrogen's effects on the uterine lining, bleeding can become heavier or more prolonged.
At the same time, declining progesterone affects more than just the menstrual cycle. Progesterone supports GABAergic activity in the brain, our primary calming pathway. Its loss can lower GABA tone, destabilise the HPA axis, and reduce stress resilience. As a result, women may experience heightened anxiety, sleep disruption, night sweats, migraines, and a reduced ability to cope with everyday stressors.
High and fluctuating oestrogen levels are a hallmark of perimenopause. Periods of oestrogen excess can stimulate histamine release and increase mast cell activation, which may contribute to symptoms such as headaches, breast tenderness, skin sensitivity, and heavier periods.
Rapid rises and falls in oestrogen can also trigger ‘withdrawal’ symptoms caused by a sudden drop in levels, like premenstrual changes, including migraines, mood changes, and fatigue.
Perimenopause and menopause symptoms
Hormonal changes during perimenopause and menopause affect multiple systems in the body.
Metabolic and physical changes
These may include increased cardiovascular risk, shifts in fat distribution and weight gain, changes in bone density leading to osteoporosis and higher fracture risk, and irregular or heavy vaginal bleeding. Urogenital symptoms are also common, including vaginal dryness, discomfort with intercourse, reduced libido, breast tenderness, and occasionally nausea.
Vasomotor and neurological symptoms
These can include hot flushes, night sweats, sleep disruption, insomnia, mood swings, irritability, migraines, and cognitive changes such as memory issues or difficulty concentrating.
Because these symptoms span cardiovascular, metabolic, neurological, and reproductive systems, perimenopause is often broader in impact than many women expect.
Get a free 7-day hormone rebalance plan
Download a free guide designed by our nutritionists here and start supporting your hormones through nutrition
How perimenopause is assessed
Perimenopause is assessed by symptoms. The presence of three of the following nine changes is typically used as a guide:
New onset heavy and/or longer flow
Shorter menstrual cycles (<26 days), due to high FSH and more rapid ovulation
New sore, swollen or lumpy breasts
New mid-sleep waking
Increased menstrual cramps
Onset of night sweats
New or increased migraine headaches
New or increased PMS mood swings
Weight gain without changes in diet
Other conditions should also be ruled out.
Perimenopause as a window of opportunity
Perimenopause is a critical stage for adopting healthy behaviour and preventive strategies.
This phase of life is not only about symptom management; it is also a key time to support long-term health. As hormones change and fluctuate, the brain and body need to adapt.
How the brain adapts to changing hormones
Before menopause, oestrogen helps the brain use glucose efficiently for energy. As oestrogen begins to fluctuate and decline during perimenopause, the brain may shift toward using ketones, an alternative fuel the body can naturally produce to maintain energy supply.
Research published in Nature Reviews Endocrinology (Brinton RD et al., 2025) describes this metabolic transition. For many women, it is a temporary and normal adaptation. However, how smoothly it occurs depends largely on metabolic health. Stable blood sugar and good insulin sensitivity support the brain's ability to switch between fuel sources, a process known as metabolic flexibility.
Importantly, this does not mean adopting a strict ketogenic or very low carbohydrate diet. The focus is on improving metabolic resilience, not eliminating carbohydrates.
If the brain adapts effectively, symptoms such as brain fog and low energy may settle. If underlying insulin resistance is present, the transition may be less efficient, and symptoms can persist, potentially increasing long-term cognitive risk.
In simple terms, strengthening metabolic resilience through balanced nutrition, strength training, restorative sleep, and stress management can help the brain navigate this transition more smoothly.
Hot flushes and brain health
Hot flushes and night sweats aren't just uncomfortable - research shows they may also be linked to subtle changes in memory and concentration. They reflect instability in the brain's temperature-regulating centres caused by fluctuating oestrogen. Repeated episodes can disrupt sleep and add stress, making concentration harder. While they don't cause serious brain problems, they're a sign to prioritise sleep, stress management, and overall metabolic health.
Insulin resistance and metabolic health
Common symptoms and signs of insulin resistance
Some women have no obvious symptoms initially, but common indicators can include:
Increased abdominal weight gain (especially around the middle)
Strong carbohydrate or sugar cravings
Energy crashes, particularly mid-afternoon
Feeling shaky, irritable, or lightheaded if meals are delayed
Brain fog or difficulty concentrating
Increased hunger shortly after eating
Darkened skin patches (often on the neck or underarms)
Elevated fasting insulin or fasting glucose on blood tests
Over time, untreated insulin resistance can increase the risk of prediabetes, type 2 diabetes, cardiovascular disease, and cognitive decline.
Many of these symptoms are commonly dismissed as ‘just hormones’ when in fact blood sugar regulation may be playing a role.
Metabolic status and targeted testing
Supporting a healthy metabolic profile is foundational during perimenopause and menopause. Hormonal shifts influence insulin sensitivity, lipid metabolism, and inflammatory tone, so monitoring key markers helps guide personalised support.
Key markers to aim for
Stable fasting glucose
Optimal insulin regulation
Higher HDL cholesterol
Lower LDL cholesterol
Low triglycerides
Further functional testing
Where appropriate, further functional testing may include:
Comprehensive thyroid panel including antibodies
Hormone metabolite testing (e.g. DUTCH or HuMap)
Comprehensive gut stool analysis
Optimising these markers supports cardiovascular, cognitive, metabolic, digestive, and hormonal resilience throughout this transition and into postmenopause.
Curious about testing?
Our practitioners use comprehensive testing including DUTCH test, GI360 and more to create personalised plans for managing perimenopause symptoms.
Book a free call to discuss whether testing could be helpful for you
Practical nutrition and lifestyle tips for perimenopause
Foods for hormone balance and weight management
Whether you are looking for a low-inflammatory, phytoestrogen-rich, or generally balanced approach - whether plant-based, vegan, vegetarian, or pescatarian - the core dietary principles are the same. If there are medical issues, gut issues, allergies, sensitivities, or intolerances, there may be even healthy foods you need to avoid temporarily while working with your practitioner to improve digestion and gut immunity.
Women can commonly experience bloating, gas, weight gain, and irregular bowel movements during this stage. The following guidelines can help:
Mostly plant-based foods - aim for a wide variety of colourful vegetables, fruits, and whole grains
Protein - aim for at least 60–70 grams per day, preferably from high-quality lean meats, eggs, dairy, nuts, and beans/legumes
Avoid processed foods - reduce ultra-processed and packaged items where possible
Herbs and spices - add these generously to your meals for anti-inflammatory and antioxidant benefits
Good fats - include extra virgin olive oil daily
Oily fish - consume twice a week (salmon, mackerel, anchovies, sardines, herring)
Cruciferous vegetables - broccoli, cauliflower, cabbage, kale, bok choy, and Brussels sprouts contain compounds (DIM, I3C) that favour 2-OH metabolism, the healthier pathway of oestrogen
Phytoestrogens - compounds found in plants such as isoflavones (soy, red clover) and lignans (lentils, chickpeas) can occupy oestrogen receptor sites
Time-restricted eating - aim to eat within a 12-hour window, with a 12-hour overnight fast
Reduce alcohol - alcohol can affect sleep quality and contribute to weight gain
The benefits of exercise in perimenopause
Regular exercise during perimenopause helps stabilise blood sugar, support healthy weight, and maintain muscle and bone strength. It can improve sleep, reduce stress and anxiety, and even ease hot flushes. Moving your body consistently helps boost energy, mood, and overall metabolic and brain health during this transitional stage - and well beyond perimenopause.
Supporting nutrition and targeted supplements
In addition to a nutrient-rich diet, certain supplements, herbs, and adaptogens can be supportive during perimenopause. Some examples include:
Magnesium - helps calm the nervous system and supports sleep. It also supports mitochondrial energy production, enhances insulin receptor function, and helps stabilise blood sugar, reducing the risk of reactive hypoglycaemia (use caution if taking metformin).
Vitamin D - supports bone and immune health.
Omega-3 fatty acids - support heart, brain, and metabolic health.
Red clover extract - may help reduce the frequency and intensity of hot flushes.
These are just a few options, and strategies can be more targeted and effective when tailored by a Nutritional Therapist to your individual needs.
Supplements are not a substitute for medical care. Always check with your healthcare professional before starting any new supplement, especially if you are taking medications or have existing health conditions.
Frequently asked questions
-
Perimenopause is the transitional phase of two to twelve years before menopause, during which hormones fluctuate and symptoms are often at their most intense. Menopause is defined as the point one year after your final period, and is usually the time of fewer or almost no symptoms.
-
Not necessarily. While hormonal shifts can influence fat distribution and metabolism, supporting insulin sensitivity through balanced nutrition, regular exercise, and good sleep can help manage weight during this transition.
-
Many perimenopause symptoms overlap with thyroid conditions, stress, and other hormonal issues. Targeted testing and working with a qualified practitioner can help identify what's driving your symptoms.
-
Yes, you can get pregnant during perimenopause. Perimenopause is the transitional phase leading up to menopause, and although hormone levels - particularly oestrogen and progesterone - fluctuate and ovulation becomes irregular, it does not stop completely until menopause is reached (defined as 12 consecutive months without a period). As long as ovulation is still occurring, even unpredictably, pregnancy remains possible. For this reason, contraception is recommended until menopause is confirmed, if pregnancy is not desired.
Key takeaways
Perimenopause can begin as early as the late 30s and last two to twelve years - it is the phase of greatest hormonal fluctuation and often the most symptoms.
Oestrogen doesn't simply decline during perimenopause; it can surge to levels much higher than in your 30s before eventually dropping, which explains why symptoms can feel so unpredictable.
Declining progesterone plays a significant role in anxiety, sleep disruption, and heavy bleeding during this phase.
Perimenopause is a window of opportunity - supporting metabolic health now can benefit your brain, bones, heart, and overall wellbeing long into postmenopause.
Insulin resistance is common during perimenopause and may be contributing to symptoms often dismissed as ‘just hormonal.’
Nutrition, exercise, sleep, and targeted supplementation can make a meaningful difference in how you feel during this transition.
Ready to get support?
At Peach Health, we support women navigating perimenopause by helping them understand their unique symptoms and stage of life. Through personalised assessment and targeted testing, we can identify underlying factors affecting energy, metabolism, hormones, and overall wellbeing - helping you make informed choices rather than guessing what might help. Our approach combines nutrition, lifestyle strategies, and supportive supplements tailored to your individual needs.
Book a free discovery call to learn how we can support you, or explore our hormone health services to find out more about our approach.
Written by
Cynthia De Maria
Registered Nutritional Therapist (mBANT, dipCNM), Women’s & Children’s Health Specialist at Peach Health