Estrogen resistance: why low estrogen does not explain everything

It is not just how much estrogen you have.

It is how much your body hears it.

That sentence captures an idea that can change the conversation around perimenopause, hormonal symptoms and women’s health: the hormonal signal does not depend only on the concentration of estradiol in the blood. It also depends on whether tissues have available receptors, what the chromatin around those genes looks like and how stable the context is where that hormone is trying to act.

That is why two women can have similar hormone levels and feel completely different.

One may have stable sleep, acceptable energy and few hot flashes. Another may experience night heat, irritability, brain fog, fatigue and dryness, even if her lab results do not look dramatic.

The difference is not always in "more or less estrogen". Sometimes the more interesting question is different:

how sensitive is your body to the estrogen signal?

Estrogen is not the same as estrogen signaling

Estradiol needs receptors to produce an effect. The two classic receptors are ERα and ERβ, encoded by the ESR1 and ESR2 genes. GPER also exists, a receptor associated with rapid signaling.

The popular conversation usually focuses on the hormone: "low estrogen", "high estrogen", "estrogen dominance". But real biology has more layers.

The final response depends on:

• how much estradiol, estrone or estriol is available;
• which receptors each tissue expresses;
• whether those receptors are accessible or silenced;
• which cofactors help or block transcription;
• what is happening with stress, sleep, inflammation, metabolism and the microbiome;
• which hormonal stage the woman is in.

The same estradiol does not mean the same effect in the brain, adipose tissue, vagina, bone, breast, gut or immune system.

The body does not respond like a flat table. It responds like a network.

What methylation has to do with it

DNA methylation is an epigenetic mark that can influence which genes are expressed. When certain regulatory regions are methylated, sometimes the gene becomes less available to produce protein.

In the case of ESR1 and ESR2, this matters because those genes encode estrogen receptors. If receptor expression changes, the same hormone can produce a different response.

This does not mean we can look at symptoms and conclude: "your receptors are methylated". We cannot. That would be a molecular statement that requires direct measurement.

What we can say more carefully is this:

hormonal sensitivity can vary between women, tissues and moments in life.

And that sensitivity can be modulated by genetics, epigenetics, inflammation, stress, sleep, diet, adiposity, microbiome and reproductive age.

What research is beginning to show

A study from the Swiss Perimenopause Study followed 129 women aged 40 to 56 for 13 months. It measured symptoms every two weeks and salivary estradiol at multiple points. The finding relevant to this discussion was that variants in estrogen receptor genes, together with estradiol fluctuations, were associated with different symptom trajectories.

The practical reading is clear: hormonal fluctuation matters, but receptor sensitivity does too.

Another line of evidence comes from extreme hormonal transitions. In a longitudinal study during pregnancy and postpartum, ESR1 methylation changed across the transition and was associated with depressive symptoms during pregnancy. ESR2 and GPER did not show the same pattern, suggesting that not all receptors behave the same way.

In adipose tissue, a mouse study showed that a high-fat diet increased methylation of the Esr1 promoter, reduced its expression and was associated with inflammation and insulin resistance. When that methylation was experimentally reduced, Esr1 increased, inflammation decreased and insulin sensitivity improved.

This does not prove that the same thing happens identically in all women. But it does open a powerful idea: metabolic tissue can also become less sensitive to estrogen signaling.

And that connects with something many women report in perimenopause: the body stops responding the same way to food, sleep, stress and exercise.

Perimenopause: not just decline, also variability

Perimenopause is not a clean, linear drop in estrogen.

It is a stage of fluctuation.

There may be weeks with high estradiol, weeks with low estradiol, less consistent ovulation, more vulnerable progesterone, more fragile sleep, more erratic cortisol and symptoms that do not follow a simple line.

If tissues also respond differently to that signal, the experience becomes even more variable.

One woman may feel anxiety, breast pain or migraine during a week of intense estrogen signaling. Another may feel brain fog, hot flashes or dryness when the signal drops or when the tissue does not respond well. Another may have both in different months.

That is why the question "do I have low estrogen?" can fall short.

Sometimes the more useful question is:

is my hormonal system producing stable signals and are my tissues reading them well?

Sleep, stress and food are not accessories

Hormonal sensitivity does not live in isolation.

Chronic stress can alter the HPA axis, increase inflammatory load and change how cortisol, progesterone and estradiol coordinate. Broken sleep can reduce recovery, affect circadian rhythm and amplify vasomotor symptoms. Food can modulate inflammation, glucose, microbiota, production of short-chain fatty acids and availability of compounds with weak or modulatory estrogenic activity.

This does not turn food into a "hormonal cure". Nor does it mean a woman is responsible for her symptoms.

It means something more sober:

the context changes the response.

A late dinner, alcohol, ultra-processed foods or low fiber intake will not have the same effect in every woman. It depends on phase, sleep, stress, reproductive stage, metabolic health, microbiota and individual sensitivity.

That is why Lua insists so much on longitudinal patterns. Not to label foods as good or bad. To understand when a combination repeats:

this food, at this time, with this sleep, in this phase, followed by these symptoms.

ERSI: a Lua Labs hypothesis

At Lua Labs we are working on a hypothesis called ERSI: Estrogen Receptor Sensitivity Index.

It is not a clinical test. It does not measure ESR1, ESR2 or real methylation. It does not diagnose estrogen resistance.

It is a way to think about a functional pattern:

when symptoms, sleep, recovery, stress, food and hormonal stage suggest that the body may be responding less steadily to hormonal changes.

An index like this would need to look at layers such as:

• hot flashes, night sweats and heat-related awakenings;
• fragmented sleep, morning energy, HRV and resting heart rate;
• mood variability, anxiety, irritability and brain fog;
• circadian stability: light, sleep, food and activity;
• stress load and recovery;
• eating pattern, fiber, ultra-processed foods, alcohol and timing;
• hormonal stage, cycle, age and previous symptoms;
• data quality and consistency.

The right output would not be:

"you have methylated estrogen receptors".

It would be something more honest:

"Your signals suggest that this week your body responded less steadily to hormonal changes. The factors that weighed most were fragmented sleep, heat-related awakenings and low recovery."

That does not replace a medical consultation. But it can help someone arrive with a clearer story.

Why this matters for Carmen

Carmen is 47 years old. She has hot flashes, insomnia, brain fog and a doctor who told her "it is your age".

The problem with that sentence is that it erases context.

Age matters, yes. But Carmen needs to know what is happening in her real body. If her symptoms worsen after weeks of broken sleep, late dinners, social alcohol, high stress and low recovery, that information matters. If she improves when she increases fiber, stabilizes routines and protects sleep, that matters too.

Not because those habits "cure" perimenopause.

But because they help us understand the system’s sensitivity.

And that longitudinal story can be much more useful than arriving at a consultation with scattered symptoms.

What we can honestly say

Estradiol concentration does not automatically equal estrogen signaling.

Receptors matter. Tissue matters. Epigenetics matters. Sleep, stress, metabolism and food can change the context where that signal happens.

We also need to be clear about the limits: direct evidence on ESR1 and ESR2 methylation in healthy perimenopause is still limited. There is no simple signature that allows an app to tell a woman that her receptors are silenced.

The responsible path is to work with patterns, not promises.

That is what Lua seeks to build: longitudinal hormonal intelligence. A way to look at the body in sequence, with food, sleep, symptoms, hormonal phase and recovery together.

Because the most useful question is not always "how much estrogen do I have".

Sometimes it is:

why is my body responding like this, at this moment, with this pattern?

Sources

• Grub J, Willi J, Süss H, Ehlert U. The role of estrogen receptor gene polymorphisms in menopausal symptoms and estradiol levels in perimenopausal women. Maturitas. 2024. DOI: 10.1016/j.maturitas.2024.107942.
• Zorzini G, Johann A, Dukic J, Gardini E, Ehlert U, et al. Longitudinal Analysis of Estrogen Receptor Gene Methylation, Estradiol, and Depressive Symptoms During the Perinatal Period. Molecular Neurobiology. 2025/2026. DOI: 10.1007/s12035-025-05556-3.
• Wu R, Li F, Wang S, Jing J, Cui X, et al. Epigenetic programming of estrogen receptor in adipocytes by high-fat diet regulates obesity-induced inflammation. JCI Insight. 2025.
• Szymański JK, Malinowska M, Jakiel G, Słabuszewska-Jóźwiak A, et al. Local estrogen therapy effects on DNA methylation dynamics in menopausal women. Journal of Applied Genetics. 2026. DOI: 10.1007/s13353-026-01056-9.
• Rong J, Xie X, Niu Y, Su Z. Correlation between the RNA Expression and the DNA Methylation of Estrogen Receptor Genes in Normal and Malignant Human Tissues. Current Issues in Molecular Biology. 2024. DOI: 10.3390/cimb46040226.
• Gutierrez-Martinez VD, León-Del-Río A, Camacho-Luis A, et al. Butyrate induces estrogen receptor alpha activation independent of estrogen stimulation in MCF-7 breast cancer cells. Genetics and Molecular Biology. 2024. DOI: 10.1590/1678-4685-gmb-2023-0110.