Can one become Hypothyroid from dieting? - Thyroid UK

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Can one become Hypothyroid from dieting?


Hello fellow sufferers!

I have just started posting here but have been reading all the posts with great interest. Thank you health unlocked.

My question is can strict dieting cause hypothyroidism? My Endo says not but I am not sure this is true.

23 months ago my THS was 2.8. Then I dieted very stricktly, but sensibly, for eighteen months and lost 20 kilos/44lbs.

I felt a lot better and looked a lot better.

Next blood test showed THS 8.7 so sent to an Endocrinoligist.

I have been on Levo three days a week for four months starting on 25 then 50 now 100mgs and my levels are now stabilised and in a good healthy thyroid range.

What I want to know is does anyone think this could have been due to my dieting.

PS I have now put 8 kilos back on. Not dieting and eating sensibly. Not pleased with this and it seems to be caused by the Levo!!

What ideas on this question would be gratefully received.

Wishing you all a Merry Christmas and a Happy and Healthy New Year.




21 Replies

Hi there, welcome :)

The thing is, when your TSH was 2.8, you were already heading into hypothyroidism. Anything above 2.0 is abnormal - despite the "normal" range - and shows that something was not quite right.

So no, dieting didn't cause it - you were already heading there, I'm afraid. It was probably the reason you put weight on the first place.

Jazzw in reply to Jazzw

Oh, and if you haven't lost the regained weight, I'd lay money on you not being on an optimal dose of thyroid replacement hormone. Unfortunately though, doctors think results in the normal range are ok. They usually aren't. {sigh}

Smaffles, extreme dieting and anorexia can induce hypothyroidism but as JazzW said, your thyroid was already struggling for you to have TSH 2.8 before you started dieting, so in your case, it's not due to dieting.

Are you really taking 100mcg 3 x week? Levothyroxine is usually taken as a daily dose.

The 8kg weight gain may be due to undermedication. If you post your thyroid results with lab ranges (figures in brackets after results) we'll advise.


I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.

Auntywoo in reply to Clutter

Thank you Clutter. My test results of two weeks ago were.

THS. 3.07. mU/L. (0.5 -6.0)

(Was 2.82 two months ago.)

FT4. 15.9. pmol/L (11.0-22.0)

FT3. 3.9. pmol/L (3.1 - 6.0)

TPO No Antibodies : 6 IU/mL ( <35 )

Vitamin D low. 40 two months ago, now 49 nmol/L (50 - 250)

Taking calcium and vitamin d after dinner in evening. Endo also has me on a high dose of Vitamin D once a month started last week 100,000iu

My cholesterol is normal.

Endo says I have sub clinical hypothyroidism.

My symptoms were feeling very cold, hair loss, very bad leg cramps nearly every night. Constipation. Dry eyes and probably other things!!

Feeling a lot better now but my husband says I stress about things a lot more than I used too!

I do take Levo 100 three days a week.

Thank you for your help.

Wendy (Smaffles)

Jazzw in reply to Auntywoo

Hi Wendy

Well, 300mcg of Levo a week works out at 40 something micrograms a day - which isn't even a starter dose of levothyroxine. Most on levothyroxine feel much better with a TSH of less than 1.0. Given your latest TSH, you really do need a raise in dose. Your levels are indeed in a "healthy thyroid range" - but your thyroid isn't healthy, so it isn't enough any more.

Your remaining symptoms are linked to undermedication. Strictly speaking, you don't have subclinical hypothyroidism if you do in fact have clinical symptoms - you simply have hypothyroidism. Nothing subclinical about it.

Auntywoo in reply to Jazzw

The symptoms I mentioned was before Levo. They have all gone now. 😃👏🏻

greygoose in reply to Auntywoo

Well, no, your symptoms haven't all gone, because weight-gain, and difficulty losing weight, are also hypo symptoms.

Clutter in reply to Auntywoo

Wendy, the good news is antibodies are negative so you don't have autoimmune thyroid disease (Hashimoto's).

You are undermedicated to have TSH rise to 3.07 from 2.82. Most people on Levothyroxine are comfortable with TSH 1.0 or lower. A dose increase of 25mcg daily or 175mcg a week will probably be enough to reduce TSH and boost FT4 and FT3 which are on the low side.

VitD is replete 75-200 and most people are comfortable around 100. 100,000iu monthly is a good dose in addition to a daily dose.

You may stress less when you're optimally medicated but I have to admit I no longer handle stress they way I used to and opt for avoiding stress rather than coping with it.


I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.

Auntywoo in reply to Clutter

thank you Clutter,

My Endo says Levo has a life of two days and taking three times a week is okay. Bad sleeping is another concern

of mine and I often only have 4/5 hours a night. Last night was four. 😬

Endo did raise dose by 25 mcg last week of middle dose.

I started with 25, then to 50 three days a week, then 100 mon. 50. wed. 100 frid. Now to 100 each of those three days.

She seems to think she has me sorted. I see her again in three months so will question it all thoroughly.

Not sure what my bit B 12 is?

Cheers Wendy.

PS you are probably in bed by now. are you in the UK? I have two children living in London. We visit every year. Son, Adam, is arriving tomorrow for three weeks with his family. First visit home in four years. 🎄😍

Clutter in reply to Auntywoo

Wendy, It doesn't matter whether you take Levothyroxine daily or weekly as long as it's sufficient dose. I don't think yours is enough.

I hope you enjoy your son and his family's visit. Must be difficult living thousands of miles away from your children.

I am in the UK and in bed :-D I'm going to stir me stumps and go downstairs and grab a snack though.

SAMBS in reply to Clutter

Hi clutter Now I'm confused by this post I've just come across today. Is the Person referred to as Smaffles/Wendy/ Auntywoo - all one and the same person? Very weird!

Yes I see the occasional later responses as Wendy/Auntywoo!

I just wish people would stick to one and same 'smiley username' ! Then at least if they put their real name I.e.Sambs, the I'm Shirley - it all sounds more plausible!

Auntywoo in reply to SAMBS

So sorry I have confused you. I tried to change from Aunty Woo to Smaffles but it didn't work hence the double up. Yes I am the same person. It seems I am still coming up as Aunty Woo. I am Wendy. I tried to cancel the Smaffles with no effect.

greygoose in reply to Auntywoo

Why are you taking calcium?

Taking vit D3 will raise your levels of calcium anyway. And you should be taking vit K2 with it. You should certainly be taking vit K2 if you're taking calcium! Vit K2 ensures that the calcium goes into the bones, and not the tissues - like the heart, and the kidneys.

Leg cramps would suggest to me that you are low on magnesium. Vit D3 and magnesium work together, so it might be a good idea to try taking a little. There are other things, but one thing at a time! :)

As you're losing your hair, you could be low on iron. Best to get that checked, too. Also your vit B12, because hypos often have low B12.

Your endo really doesn't know much about thyroid, does she. You really, really do need an increase in dose. 100 mcg three times a week is a stupid dose. Your FT3 is very, very low, and that will make you continue to put on weight. :(

Yes... I lost three stones with slimming workd, having been on levo only for several years. It was only after i lost the weight, i realised i felt really hypothyroid. It took a whille to change meds and i ended up on liothyronine. (T3).

Much later, i read somewhere that losing weight can permanently hinder t4 to t3 conversion. If you cant turn your t4 into t3, you end up hypothyroid, even with good free t4 levels.

If i can find the paper which describes it. I will post a link.

G x

Auntywoo in reply to galathea

Thank you I Would like to read that info. Wendy. ( Aunty Woo)

Jazzw in reply to Auntywoo

Out of interest, how did you lose the weight, Auntywoo? Was it a low carb diet by any chance?

Auntywoo in reply to Jazzw

Yes but not too low. Ate most things. Gave up alcohol except for a glass or 2 of red on Saturday nights with the pasta breakout I had most Saturday's. I was determined to lose it was 92 kms at the beginning got down to 71.4. Now 79. 😬🙄

Auntywoo in reply to Auntywoo

Not kms. Lol. Kilos.

Dee1 in reply to galathea

I would be fascinated to read this too!

Interesting considerations

At the same time, adrenals issues might be something worth a second thought from here:

Bitty ideas to try to quilt together but it's a safety blanket that comes in time.

It's be nice if there were better diagnostics that could really help narrow down any one's personal situation...

I lost 3 stone prior to underactive thyroid diagnosis and couldnt understand why when i was doing all of the right things...eating healthily and exercising why i was starting to put weight on...personally i think i was overdoing the exercise whilst probably not eating enough and i reckon i depleted my T3. I am now heading for 6 stone heavier than pre-diagnosis and am still trying to figure it all out!

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