Lipedema and MCAS: Could Hormones, Histamine and Mast Cells Be Connected
If you've been diagnosed with lipedema, you've probably been told it's a hormone-related fat disorder and left to work out what that actually means for you. It's not a great explanation on its own, and it isn't the whole story.
Lipedema causes a disproportionate build-up of fat in the legs, hips, buttocks and sometimes the arms, while the hands and feet are spared. That distribution is one of the things that separates it from ordinary weight gain or lymphoedema. It mostly affects women, and it comes with pain, tenderness, easy bruising and swelling that people are often told is "just how their body is."
What's interesting is a question researchers have started asking more seriously: are hormonal changes, histamine and mast cell activity actually linked mechanisms in lipedema, rather than three separate things that happen to turn up in the same patients? And if they are linked, does that mean lipedema is partly driven by Mast Cell Activation Syndrome (MCAS) and ongoing inflammation, rather than being purely a fat storage problem that MCAS happens to sit alongside?
Why Hormones Keep Coming Up
Lipedema has a habit of appearing, or getting noticeably worse, at exactly the moments a woman's hormones are shifting: puberty, pregnancy, perimenopause, menopause. That's too consistent a pattern to be coincidence.
Oestrogen is deeply involved in how fat cells behave, how they're distributed around the body, and how they interact with inflammatory signalling. It also acts on blood vessels and on several types of immune cell, mast cells included. So there's a plausible route from "hormones changed" to "mast cells behaved differently" to "adipose tissue started changing."
That doesn't mean lipedema is simply about having too much oestrogen. Blood tests measuring circulating oestrogen rarely explain much on their own. What probably matters more is how the tissue itself is responding, receptor sensitivity, local metabolism of the hormone, that sort of thing, rather than the number on a lab report.
What's Actually Happening in the Tissue
This is where it stops being theoretical, because a couple of biopsy studies have actually looked.
One, from Kruppa and colleagues in 2023, took fat tissue samples from 32 women with lipedema across the full range of disease stages and compared them with matched controls. The lipedema tissue showed larger fat cells, progressively worse fibrosis as the disease advanced, and a shift towards a particular type of macrophage that gives the inflammation a different character to what you'd see in ordinary obesity. Tellingly, this was only true in the affected thighs, not in unaffected abdominal fat from the same women. So whatever's going on isn't simply systemic, it's happening locally, in the tissue that's actually diseased.
The second study is the one we find more compelling. Bonetti and colleagues, working with lipedema researcher Karen Herbst, went looking specifically for mast cells and histamine in lipedema tissue. They found both, mast cells were clearly present on biopsy, and histamine and its breakdown products were significantly higher than in controls. Then they gave a group of patients two weeks of sodium cromoglycate, a mast cell stabiliser, and histamine levels in the tissue dropped.
It's a small pilot study, and it needs repeating in a larger group before anyone builds a treatment protocol around it. But it's genuinely good evidence, tissue level, not just questionnaires, that mast cells are doing something in lipedema fat, and that calming them down changes the biochemistry.
How MCAS and Histamine Might Fit In Lipedema
MCAS involves mast cells releasing their contents too readily or too often, histamine, cytokines, proteases, prostaglandins, leukotrienes, the usual cast. In lipedema tissue, that release could plausibly be driving some of what we see on biopsy: the inflammation, the leaky vessels, the fibrosis creeping in over time.
And the hormone piece slots in neatly here too. Mast cells carry oestrogen receptors, and there's good reason to think oestrogen signalling affects how readily they degranulate. So you get a chain that actually makes mechanistic sense: hormonal shifts affect mast cell behaviour, mast cells release mediators that drive local inflammation and vascular change, and that inflammation contributes to the fibrosis and tissue remodelling researchers are finding on biopsy. Hormones, histamine and mast cells stop looking like three coincidences and start looking like steps in the same process.
But Is Lipedema Actually a Symptom of MCAS?
We want to be careful here, because we think the strongest version of this claim goes further than the evidence allows, and it matters for what you tell a patient to expect.
What the research supports is that mast cells and local histamine release are involved in lipedema's tissue pathology, contributing to the inflammation, fibrosis and vascular changes behind the pain and swelling. That's a solid, useful finding.
What it doesn't support is that lipedema is caused by MCAS as a systemic condition. A few reasons we'd hold that line:
Most lipedema patients simply don't meet the formal diagnostic bar for MCAS, episodic symptoms, mediators that rise during an episode, response to mast cell treatment. Local mast cell activity in a fat pad and a systemic MCAS diagnosis are not the same thing, and treating them as interchangeable means you'll end up diagnosing MCAS in people who don't actually have it.
The trigger pattern doesn't fit either. If MCAS were driving lipedema from the start, you wouldn't expect such a tight relationship with puberty, pregnancy and menopause specifically. That pattern points to a hormonal or genetic predisposition in the fat tissue itself as the starting point, with mast cells joining in afterward rather than kicking things off.
And causation might well run backwards, or both ways at once. Expanding fat tissue becomes hypoxic and mechanically stressed, and that alone is known to recruit and activate mast cells and macrophages, this is well established in obesity research. So it's entirely plausible that a hormonally-driven change in the fat pad creates the conditions, low oxygen, stretched fascia, mechanical strain, that then pull mast cells in, which then make the fibrosis and swelling worse, in a loop that feeds itself. That's a genuinely different story to "MCAS causes lipedema," even though the biopsy might look similar either way.
Our honest take: lipedema is a primary disorder of fat and connective tissue with a real, and clinically important, inflammatory layer on top that likely makes things worse once it's established. Treating that inflammatory layer, whether or not someone technically qualifies for an MCAS diagnosis, makes sense and is backed by decent evidence. But telling a patient their lipedema is a symptom of MCAS oversells what we know, and risks them expecting the fat and fibrosis to disappear once the mast cells are calmed down. It won't, not on its own.
And Then There's Connective Tissue
None of this cancels out the connective tissue side of the story, it probably runs alongside it. Hypermobile Ehlers-Danlos syndrome involves a genuine collagen defect, and that gives a straightforward structural reason why fascia and vessel walls in lipedema tissue might lose their normal recoil and start leaking under pressure. A 2025 study found 44% of women with lipedema reported hypermobile joints as adults, and 60% remembered being hypermobile as children, numbers well beyond what you'd expect by chance.
Loose or fragile connective tissue might also make it easier for mast cells sitting nearby to degranulate, since they live in close contact with fascia, vessels and nerves throughout the body. So a lot of patients are probably carrying two separate vulnerabilities at once, one hormonal and adipose, one structural, with mast cells and histamine amplifying whichever one is already in motion rather than being the sole cause of either.
The Bigger Picture
Lipedema is looking less and less like a single, simple disorder of fat storage. What's emerging is a picture where hormonal signalling, adipose and connective tissue biology, collagen structure, blood vessels, lymphatics and mast cell activity are all pulling on the same rope. None of them works alone. Hormonal change can prime the tissue and influence how mast cells behave. Mast cells, once active, drive inflammation and fibrosis. Loose connective tissue can make mast cell activation easier to trigger while also independently affecting vessels and drainage.
The research genuinely supports hormones, histamine and mast cells as connected parts of what's going on in lipedema. It just doesn't support collapsing lipedema down to "a symptom of MCAS," and that distinction is worth holding onto, both for accuracy and for what you can honestly tell a patient to expect from treatment.
How The Autoimmune Clinic Can Help
At The Autoimmune Clinic, we work with individuals with complex and chronic health conditions, including Mast Cell Activation Syndrome (MCAS), histamine intolerance, hormonal and metabolic imbalances, gut dysfunction and chronic inflammation.
For someone with lipedema, particularly where there are symptoms suggestive of mast-cell or histamine involvement, our approach is to look beyond the diagnosis itself and consider the wider picture.
This may include exploring hormonal health, metabolic health, gut function, nutrient status, inflammation, immune regulation and other factors that may be contributing to symptoms.
Our aim is not to treat lipedema as a single isolated condition, but to understand what may be driving symptoms for the individual and develop a personalised approach to support their overall health.
If you would like to learn more about how we work, you can book a discovery call with one of our practitioners.
