Why Is My Hair Thinning in Perimenopause (And Why Does It Get Worse Every Time You Diet)?
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Why Is My Hair Thinning in Perimenopause (And Why Does It Get Worse Every Time You Diet)?
Your hair is thinning in perimenopause because oestrogen is falling, and as it falls the balance between oestrogen and androgens shifts. Oestrogen keeps each hair in its growing phase for longer. When oestrogen drops, that growing phase shortens, hairs shed sooner than they used to, and what grows back comes in finer. At the same time the androgens you have always carried become relatively more influential, and they shrink the follicle itself a little more with every cycle. That is why the parting widens and the ponytail gets thinner instead of a bald patch appearing.
The second answer is the one almost nobody gets told. Sharp calorie restriction is one of the best documented triggers for a separate kind of shedding called telogen effluvium. You cut your food right down in January. The hair starts coming out in the shower in April. That is a 3 month gap, so most women never connect the two, and they blame perimenopause for something the diet did.
Up to 52% of postmenopausal women have some degree of female pattern hair loss. It is one of the most common physical changes of midlife and one of the least discussed in a 10 minute appointment.
Key Takeaways
Up to 52% of postmenopausal women show female pattern hair loss, according to a cross-sectional study of 178 women published in Menopause
Falling oestrogen shortens the growing phase of each hair, so you shed sooner and regrow finer
The relative rise in androgens shrinks the follicle, which is why the parting widens rather than bald patches appearing
Rapid weight loss and low protein trigger a separate kind of shedding that shows up around 3 months after the diet, not during it
Eating enough, getting enough protein and asking your GP to check your iron and thyroid protects more hair than any shampoo
The morning you actually notice it
It is never a dramatic moment. That is part of the problem.
It is the plughole after a shower. It is the hairband that goes round 4 times now instead of 3. It is the light in a hotel bathroom catching your parting from an angle you do not usually see, and something in your stomach dropping. You put your fingers in your hair and you cannot tell whether it is genuinely thinner or whether you are imagining it, because you have never really looked at your own scalp before.
So you say nothing. You buy a thickening shampoo. You start parting it on the other side. You stop wearing it up.
And when you do mention it, at the end of an appointment you booked for something else, it gets a nod and a comment about stress, and you leave with nothing.
Here is what I want you to know before anything else. This is not vanity and it is not nothing. A 2024 review of the quality of life impact found that female pattern hair loss measurably affects self-esteem, mood and social confidence, and that the effect gets stronger as the loss progresses. Your hair is one of the few parts of you that other people see every single day. Feeling like it is disappearing without anyone explaining why is a legitimate thing to be upset about.
I am 55. I have been through my own perimenopause and out the other side, and I have watched hundreds of women in their 40s and 50s go quiet about this particular one. It comes up last, usually near the end of a conversation about something else, usually with an apology attached.
You do not need to apologise for wanting to understand your own head.
What is actually happening at the follicle
Every hair on your head runs its own cycle, independently of the ones next to it. It grows for a few years. Then it stops and rests. Then it falls out and the follicle starts again. That is why you lose 50 to 100 hairs a day and never notice, because only a small percentage of your hair is in the shedding stage at any one time.
Oestrogen influences how long the growing stage lasts. A 2025 review in Maturitas set out the mechanism clearly: as oestrogen falls, the growing phase shortens, hair fibres become thinner and breakage increases. So each hair spends less time growing, comes out sooner, and the replacement is finer than the one it replaced.
That alone would thin your hair. But there is a second thing happening on top of it.
Your body has always produced androgens. They are not a male hormone that has arrived out of nowhere. What changes in perimenopause is the ratio. Oestrogen and progesterone fall away faster than androgens do, so the androgens become relatively more influential without necessarily rising at all. And androgens, particularly a form called DHT, bind to receptors in the follicles along the top of your scalp and gradually shrink them. Dermatologists call this miniaturisation. The follicle produces a thinner, shorter, less pigmented hair each time, until eventually it produces something closer to fluff.
That is why it looks the way it looks. Female pattern hair loss spreads across the crown and widens the parting. The hairline at the front usually stays. It is diffuse rather than patchy, which is exactly why it is so hard to prove to yourself in the mirror and so easy for someone else to tell you it looks fine.
The numbers are not small. That cross-sectional study of 178 postmenopausal women, average age 58.8, published in the journal Menopause, found female pattern hair loss in 52.2% of them. Most of it was mild: 73.2% were at the earliest grade, 22.6% moderate, 4.3% severe. A 2025 review in Frontiers in Pharmacology put the same figure at up to 52% and described hair loss as an underrecognised burden of menopause.
Underrecognised is the right word. A 2025 analysis in the Journal of Cosmetic Dermatology looked at every piece of research on female pattern hair loss published between 1957 and 2024 and concluded it remains a common but understudied condition. Half of us go through it. Almost nobody studies it properly. Then we are told it is just age.
Why it gets worse in the 3 months after a diet
This is the part I care most about, because it is the part you can do something about today.
Hair growth is expensive. Your body builds it out of protein, and it is not an organ you need in order to survive. So when energy comes in short, hair is one of the first places your body economises. It pushes a large batch of follicles out of the growing stage and into the resting stage all at once.
The catch is the delay. Those hairs do not fall out immediately. They sit there for roughly 3 months and then come out together. Telogen effluvium typically appears around 3 months after the trigger and can carry on shedding for about 6 months after that.
So the timeline goes like this. You start a very low calorie plan in January and feel virtuous. You come off it in February. In April your hair starts coming out in handfuls and you have absolutely no idea why, because by then you are eating normally again and the diet feels like ancient history.
A 2024 retrospective study of 140 patients with telogen effluvium, 110 of them women, is one of a growing number of papers linking rapid weight loss directly to this pattern. The older clinical literature is equally clear: crash dieting causes it, and the mechanism is a combination of not enough total energy, not enough protein, and the shortfalls in iron, zinc and essential fats that come with any plan built on cutting rather than choosing.
If you have spent 20 years doing January diets, you may have been running this cycle over and over without ever seeing the connection. And each round has landed on top of the underlying perimenopause thinning, which is quietly progressing in the background regardless.
That is not you doing something wrong. That is the wrong plan, repeated.
What actually protects it
I am a trainer, not a doctor, so let me be clear about the line. Hair loss can have medical causes that need a medical answer. Thyroid problems, low ferritin, some medications and some autoimmune conditions all show up as thinning hair, and none of them can be fixed with better breakfasts. If your hair is coming out fast, in patches, or with scalp itching or soreness, that is a GP appointment, and the British Menopause Society has useful information you can take with you.
What I can tell you is what stops making it worse.
Eat enough, consistently. This is the whole ballgame. Hair is built out of surplus, and there is no surplus on 1,200 calories. Not doing another aggressive deficit is the single most protective thing on this list. Body fat can still come down. It comes down slower, from a smaller gap, with your hair still attached.
Get your protein up and spread it out. Hair is roughly 95% keratin, which is a protein. Postmenopausal muscle already needs a bigger dose of protein to respond, and the same food supports both. Aim for a proper serving at each meal rather than a token amount at breakfast and the bulk of it at 8pm.
Ask for a blood test rather than guessing. Ferritin and thyroid function are the 2 most useful things to have checked, and if you are still having heavy periods, low iron is far from unlikely. Do not start supplementing iron on a hunch. Too much is its own problem. Ask, test, then act on the number.
Strength train, and do not use cardio as a punishment. Long grinding cardio sessions on top of restricted food is the exact combination that pushes follicles into the resting stage. Strength work asks for the food rather than burning through it, and it protects the muscle you are otherwise losing at the same time.
Be gentle with what is left. Loose ties instead of tight ones. Less heat. Less traction at the parting. It will not regrow anything, but constant tension at the hairline does real damage on top of everything else.
Then wait properly. Hair moves at the speed of hair. Roughly 1 centimetre a month. If you fix your food in September you will start seeing new growth at the parting somewhere around Christmas, and it will look like short fluffy bits standing up. Those are not flyaways. That is the point where it worked.
Frequently Asked Questions
Is hair thinning in perimenopause permanent?
The pattern loss driven by hormones tends to be progressive if nothing changes, which is why it is worth taking seriously early rather than waiting to see. The shedding caused by dieting, stress or illness is different, and that type usually does recover once the trigger is removed, although it takes 6 to 12 months to look normal again. Many women have both at once, which is why it feels so confusing.
Will HRT stop my hair falling out?
That is a conversation for your GP or menopause specialist, not for me, and the evidence on hair specifically is a lot less settled than the evidence on flushes or bone. What I would say is that HRT is not a reason to skip the food side of this. If you are still eating 1,200 calories and training 6 times a week, you are working against yourself whatever else you are taking.
How much hair loss is normal?
Somewhere between 50 and 100 hairs a day is ordinary and always has been. What matters is change: more in the plughole than there used to be, a wider parting, a thinner ponytail, or seeing scalp where you did not see it before. Take a photo of your parting in the same light once a month. It is far more reliable than trying to remember what it looked like.
Do hair supplements work?
If you are genuinely low in something, correcting it helps. If you are not, taking more of it does not, and some things are actively unhelpful in excess. That is why testing beats guessing. Most of the money spent on hair supplements in this country is spent by women who would get more from an extra 30 grams of protein a day and 300 more calories.
Can Body Reclaim help with this?
Body Reclaim is not a hair program, and I would not sell it to you as one. What it does do is take away the pattern that makes this worse: the restrict, crash, restart cycle that pushes your hair into shedding 3 months later. It starts with energy, because nothing sticks while you are running on empty, then builds strength and food you can actually keep up. Body fat can still be a goal. It just stops being the only thing on the list. Join the waitlist to be notified when the next intake opens.
Half of the women reading this will go through some version of what I have just described. Almost none of them will be told about it in advance, and a good number will spend money on shampoo before anyone mentions oestrogen, iron or protein.
You are not imagining it, and you are not being vain. You are watching a real physical change happen to your body without an explanation, which is exactly what perimenopause does over and over again in different disguises.
Start with food. Eat enough of it. Get the protein in. Get your bloods checked. Stop the January diet before it costs you another 3 months of hair in April. None of that is dramatic and none of it is quick, but it is the part that is actually in your hands, and it works in the same direction as everything else your body needs right now.
Join the waitlist to be notified when the next Body Reclaim enrolment opens.
About the author. Jane Cox is a personal trainer and menopause specialist based in Bournemouth, with more than 20 years in fitness. She is 55, went through her own perimenopause, lost 5 stone, and now works with women over 40 who are tired of being handed advice built for a different body. She is the creator of Body Reclaim, a 12 week program that starts with energy and builds from there.
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