Your Gut Health Is Affecting Your Hormones More Than You Think

Something I hear from clients a lot around this time of year is a version of the same thing. They've been on holiday, or they're about to go, and the usual structure falls away. More alcohol, more carb-heavy meals, less fibre, more sugar in the form of ice cream and holiday treats, more social commitments, more irregular eating. And underneath all of it, for a lot of women, a quiet anxiety about how their body looks on the beach. Within a few weeks the gut starts to protest. More bloated, more tired, more foggy. And then, reliably, the period arrives heavier than usual and the PMS is back in a way it hadn't been for months.

I notice the same pattern in myself. When my diet shifts and my routine goes out of the window, my gut feels it quickly. And when my gut feels it, my hormones feel it too.

I know what's happening when it does. Not because I've read about it, but because I've lived it enough times to see the pattern clearly: when my gut is struggling, my hormones feel it. And when my hormones are struggling, my gut feels that too. They are not two separate systems operating independently. They are in constant conversation.

If you've been treating your bloating and your PMS as two different problems, this might be the most useful thing you read today.

Not sure which pattern is driving your symptoms? The Body Pattern Quiz takes three minutes and gives you a clearer picture of where to start.

The gut-mood spiral most women don't recognise

Something I see constantly in my practice is this: a woman comes in with bloating and irregular bowel movements, but what she's most distressed about is her anxiety, her mood swings, her inability to cope with things that didn't used to bother her. She describes feeling overwhelmed by small demands, irritable with her partner and children, exhausted in a way that sleep doesn't fix.

What she doesn't realise is that these things are connected. When the gut is struggling, it sends distress signals to the brain via the gut-brain axis, the communication highway that runs between your digestive system and your nervous system. Your gut produces approximately 90% of your body's serotonin, the neurotransmitter most associated with mood, calm, and emotional resilience. When your gut is inflamed or imbalanced, that production is disrupted, and the effects show up not just in your digestion but in your mental and emotional state.

Many of the women I work with have been stuck in what I'd describe as a fight, flight, freeze, or fawn response for so long that it feels like their personality. They feel overwhelmed by the smallest demands, suffer from persistent low moods or mood swings, experience social anxiety that makes ordinary situations feel impossible on some days, and carry a brain fog so thick it feels like being wrapped in cotton wool. And often it's almost a permanent state that gets meaningfully worse in the second half of their cycle.

The gut-mood connection also drives food choices in a way that can feel impossible to break. When you're bloated, uncomfortable, and anxious, your body craves quick energy, which usually means sugar and ultra-processed food. Those choices then feed the gut imbalance that caused the mood disruption in the first place. It's a loop, not a character flaw.

What the estrobolome is and why it changes everything

Inside your gut lives a specific community of bacteria whose job is to manage how oestrogen moves through your body. This community is called the estrobolome, and it works like your body's oestrogen waste management team.

Here's how it works. Your liver processes used oestrogen and packages it up for removal from the body. Those packages travel to the gut ready to be excreted. The estrobolome, when it's healthy and balanced, keeps those packages intact and escorts the oestrogen out. But when the gut microbiome is disrupted, certain bacteria produce too much of an enzyme called beta-glucuronidase, which breaks those packages open. The oestrogen gets unpacked and reabsorbed back into the bloodstream instead of leaving the body.

The result is that your body ends up recirculating oestrogen it was supposed to excrete. Over time, this contributes to oestrogen dominance: more oestrogen relative to progesterone than your body needs, which shows up as worsening PMS, heavier and more painful periods, mood swings, breast tenderness, bloating in the second half of your cycle, and hormonal weight gain, particularly around the hips, thighs, and midsection.

This is why I never work on hormones without also looking at the gut. They are the same conversation.

New research explains why women's guts are more sensitive than men's

In December 2025, researchers at the University of California, San Francisco published a study in the journal Science showing that oestrogen activates previously unknown pathways in the colon that make the female gut more sensitive to certain foods and their breakdown products. When male mice were given oestrogen to mimic female hormone levels, their gut pain sensitivity increased to match that of females.

The research also suggests why women's gut symptoms often shift across the menstrual cycle, and why some women find their bloating, cramping, and digestive discomfort is significantly worse in the second half of the month. Women are approximately 80% more likely than men to be diagnosed with irritable bowel syndrome, and this research begins to explain the biological mechanism behind that gap.

This is not fringe science. It's published in one of the world's leading scientific journals, and it confirms what many women have always known from their own bodies: the gut and the hormones are not separate problems.

What disrupts the estrobolome and the gut microbiome

The estrobolome is sensitive. The balance of gut bacteria that keeps oestrogen clearance working properly can be disrupted by a range of factors that most women in their thirties are regularly exposed to, including a diet high in ultra-processed foods and added sugar, antibiotics (even a single course can alter the microbiome significantly), chronic stress and elevated cortisol, disrupted sleep, alcohol, environmental toxins, and a lack of dietary fibre to feed the beneficial bacteria.

The summer holiday pattern is a useful illustration of this. The combination of more alcohol, more sugar, more processed food, irregular meals, social stress, disrupted sleep, and less fibre hits the gut microbiome from several directions at once. The result, for a lot of women, is bloating, brain fog, heavier periods, and returning PMS, often within a few weeks. When they return to their usual way of eating, those symptoms tend to resolve relatively quickly, which tells you everything you need to know about the relationship between diet, gut health, and hormones.

The first things to change when you start supporting your gut

In my practice, the first thing most women notice when we begin working on gut health is not actually a gut symptom. It's more stable energy and lifting brain fog, usually within the first couple of weeks. The bloating tends to resolve relatively quickly once we address blood sugar regulation, introduce more balanced meals, and increase fibre intake consistently.

The approach I use is straightforward in principle, though it takes practice to make it a habit. The foundation is what I think of as a balanced plate: roughly half vegetables, which also provide the fibre your gut bacteria need to thrive, a quarter lean protein, and a quarter carbohydrates, with a small amount of healthy fat. Carbohydrates are not the enemy here and are often optional depending on the individual, but they are not something to fear. The goal is nourishment and balance, not restriction.

Proper hydration is also part of this foundation. Coffee and black tea are diuretics that can contribute to constipation and gut motility issues, and many women are genuinely under-hydrated in a way that affects their digestion before anything else is addressed.

The changes that work are the ones that are achievable for you specifically, not the ones that require a complete overhaul of your life. Small, consistent shifts in the right direction compound over time in a way that dramatic overhauls rarely do.

What your gut symptoms might actually be telling you about your hormones

If your bloating is worse in the second half of your cycle, it's worth considering whether the estrobolome might be part of the picture. If your PMS has been getting worse over time rather than staying consistent, gut health is one of the first places I'd look. If you experience mood shifts, anxiety, or brain fog that track with your cycle, the gut-brain axis and gut-hormone connection are worth exploring.

The gut and the hormones are not two separate problems requiring two separate solutions. They are one interconnected system, and supporting one almost always helps the other. That's not a theory. It's something I've seen in my own body and in the bodies of the women I work with, consistently, for years.

If you want to understand which pattern is most likely driving your symptoms, the Body Pattern Quiz is where I start with every woman who comes to me. Three minutes, free, and it gives you something concrete to take into any conversation about your health.

And if you've been struggling with persistent exhaustion or symptoms your doctor hasn't been able to explain, the Everything Looks Fine blog post explains what standard testing misses and what a more complete investigation actually looks like.