If you have hypothyroidism and you feel worse after hot yoga, saunas, cold plunges or high intensity training, you are not imagining it and you are not lazy. For many women with an underactive thyroid, hard training and extreme temperature exposure add stress to a system that is already short on fuel. Doing less, and doing it heavier and slower, is often what turns things around.

this is the first of eight letters about the years i spent solving my own thyroid, as a mother, a founder, and a woman about to turn 42. it is my story, not a prescription. please read the note at the bottom.

It started after a baby, which is the part almost nobody warns you about

Mine arrived postpartum. That is common enough to have its own name, postpartum thyroiditis, and it is one of the most under-recognised things that happens to women's bodies. It gets waved away as new-mother tiredness, because of course you are tired, you have a baby. So the months pass and the tiredness does not lift and you quietly begin to believe the problem is you.

I want to say this plainly, because it took me too long to hear it. Exhaustion that does not resolve is information. It is worth a blood test, not a better morning routine.

Everything I was doing to feel better was making me worse

Here is what my week looked like when I was at my most depleted, and every single item on this list was something I believed was good for me.

• Hot yoga, three times a week
• Sauna, two to three times a week
• Cold plunges, because everyone in Bali is doing them
• High intensity workouts, because that is what you do when you want results

I was disciplined. I was consistent. I was proud of it. And I was getting more exhausted every month, which I interpreted as evidence that I needed to try harder.

That is the trap, and I think it is a particularly feminine one. When we feel bad, we assume we have not done enough. It rarely occurs to us that we have done too much.

What I changed, and how quickly it worked

Solving my thyroid meant doing almost everything the opposite way to how I had been doing it.

The hot yoga went. All three sessions. In its place, two sessions a week at the gym with proper weights, moving slowly, resting properly between sets. Heavier and less often, rather than lighter and constantly.

The high intensity training went. Every bit of it. Replaced with easy walks, the kind where you can hold a conversation the whole way.

The sauna and the cold plunges went. Both are wonderful for many people. Neither was right for me at that point, and I had to be honest that I was doing them partly because everyone here does.

And then I added one thing back, purely for joy. A Bollywood dance class on Fridays. Not training. Not a protocol. An hour a week of moving because it is delightful, which turns out to be its own kind of medicine.

It works like a charm. I say that carefully, because one woman's experience is not evidence, but the shift was not subtle and it was not slow.

The traffic, and what I did instead

Today I was meant to be at an appointment at four o'clock. The traffic was genuinely terrible. And I cancelled, at the last minute, and went home and rested instead.

The old version of me would have pushed through it. Arrived late and flustered, apologised too much, felt terrible about it for the rest of the evening, and been wrung out by nine. I would have spent an entire day's energy on twenty minutes of traffic.

I am not telling you this because cancelling appointments is a health strategy. I am telling you because learning to not respond in a stressful way to ordinary changes has done more for my thyroid than any single supplement on my shelf. That letter is coming, it is number seven.

The things I do daily, and what the research actually says

I will go through each of these properly across the series, including where the evidence is genuinely good and where it is only tradition. Both of those are worth knowing, and I would rather you heard the difference from me than from someone selling you something.

• Black seed oil. Of everything on this list, this has some of the more interesting human research behind it in autoimmune thyroid disease. Letter five.
• Red light therapy, twenty minutes at night. Photobiomodulation for the thyroid has real published trials, which surprised me. Letter six.
• Selenium, including brazil nuts. Good evidence, and a genuine upper limit that almost nobody mentions. Letter four.
• Magnesium, and roasted pumpkin seeds. Letter four.
• Castor oil on the belly button, and castor oil body wraps. This one is tradition rather than trial data, and I will say so plainly. Letter five.

Turning 42, and the door I can hear knocking

I turn 42 this year, which means perimenopause is no longer a distant thing that happens to other women. It is at the door. And it is raising the stakes on all of this, because the thyroid and this transition are tangled together in ways I am only beginning to understand.

Being a woman is complicated. We were handed no user's manual. It is so easy to burn out and then look around for someone to blame.

So much of the ordinary day is quietly designed to drain us. Reaching for the phone before we have opened both eyes. Scrolling past a hundred lives before breakfast. None of it feels like a decision, which is exactly why it costs so much.

Loves, we really do need to take care. To let go of a great many expectations. To get back to the basics.

The eight letters

1. The year I did everything right and felt worse. You are here.
2. The numbers that actually matter, and what to ask your doctor for
3. Exercise, inverted: why heavy and slow beats hot and fast
4. The minerals: selenium, magnesium, and the brazil nut ceiling
5. Black seed oil and castor oil: the studied and the traditional
6. Red light at night: what the thyroid trials actually found
7. The nervous system, the traffic, and the cost of automatic habits
8. Forty-two: the thyroid at the door of perimenopause

Frequently asked questions

Can exercise make hypothyroidism worse?

High intensity exercise can leave some people with an underactive thyroid feeling more depleted rather than more energised, because intense training raises the body's overall stress load at a time when energy production is already impaired. Many women report doing better on resistance training with real rest between sets, plus easy walking, than on high intensity intervals. This is individual, so it is worth tracking how you feel in the day or two after a session rather than only during it.

Is sauna or cold plunging bad for hypothyroidism?

Neither is inherently harmful, and plenty of people with thyroid conditions use both without trouble. But both are deliberate stressors, and when someone is already depleted they can add to the load rather than build resilience. If you consistently feel drained rather than restored in the hours afterwards, that is worth listening to.

What is postpartum thyroiditis?

Postpartum thyroiditis is inflammation of the thyroid gland that develops in the year after giving birth. It often begins with a brief overactive phase and moves into an underactive one. It is frequently missed because the symptoms, exhaustion and low mood among them, are assumed to be a normal part of new motherhood. Some women recover fully and some go on to need long-term thyroid support, which is why testing and follow-up matter.

Why do I feel exhausted even though my thyroid results are normal?

Fatigue has many causes beyond the thyroid, including iron deficiency, low vitamin D, sleep disruption, depression and perimenopause, so persistent exhaustion always deserves a proper workup rather than assuming one answer. It is also worth asking which thyroid markers were actually tested, since a single TSH result does not tell the whole picture. That is the subject of the next letter.

Does stress affect thyroid function?

Chronic stress is understood to influence thyroid function through the hypothalamic-pituitary axis and can affect how the body converts and uses thyroid hormone. This does not mean stress causes thyroid disease or that managing stress replaces treatment. It does mean that for many people, lowering the daily stress load is a meaningful part of feeling better alongside proper medical care.

Next letter, the blood tests. Which ones to ask for, why a single number is not enough, and the question that finally got me a useful answer.

With love from Bali,
Myrah