Fasting and hypothyroidism

[bambuko]

Anybody knows about any studies/research into this topic?

I am not interested in anecdotes or opinions - I would like to know whether there are any scientific papers on the subject?

[SlowDragon Administrator]

Here

pubmed.ncbi.nlm.nih.gov/252...

TSH was suppressed in all subjects after food irrespective of the fasting levels. Free T4 values did not change significantly. This resulted in reclassification of 15 out of 20 (75%) subjects as subclinical hypothyroidism (SCH) based on fasting values whose TSH values were otherwise within range in the postprandial sample. This may have an impact on the diagnosis and management of hypothyroidism especially where even marginal changes in TSH may be clinically relevant as in SCH and in pregnancy.

Conclusion: TSH levels showed a statistically significant decline postprandially in comparison to fasting values. This may have clinical implications in the diagnosis and management of hypothyroidism, especially SCH.

[Hidden in reply to SlowDragon]

That’s fascinating

[SlowDragon Administrator]

Time of day also important

pubmed.ncbi.nlm.nih.gov/258...

TSH followed a diurnal rhythm with a peak level at 23.30 h and a trough level at 14.30 h. Four subjects had TSH trough levels within the normal range, but with peak levels outside this range. FT4 and FT3 levels fell from their highest levels some three hours after ingestion to the lowest levels just prior to the next dose. This study shows that there are significant time-related variabilities in TSH and thyroid hormone levels in treated hypothyroid patients. This should be taken into account when interpreting results of their thyroid function tests.

[Blackpanther46 in reply to SlowDragon]

What is that in plain English? I,ve read it and still don't understand when is best

[SlowDragon Administrator in reply to Blackpanther46]

TSH is highest in middle of night...drops to lowest point after lunch

Four people tested ...TSH tested at lowest point of day (after lunch) result was within range ...

Tested at Highest point of day (early morning) TSH was above range

So if GP will only treat if TSH is outside range ...get TSH tested as early as possible in morning before eating or drinking anything other than water....which by some strange coincidence is EXACTLY what we always recommend on here (as do some enlightened endocrinologists)

Lowest Ft4 ...take last dose levothyroxine 24 hours before test

[Blackpanther46 in reply to SlowDragon]

Thanks that’s an easier to understand explanation

Makes sense now I think is highest TSH good then I thought a high TSH was bad if over 4.5 ?

[SlowDragon Administrator in reply to Blackpanther46]

Depends...if you are looking for dose increase in levothyroxine you want highest TSH (as that’s all most medics look at)

[Cooper27]

It may depend what sort of fasting you're talking about. I came across this paper a while ago on the impact of very low calorie diets on T3 levels, if a low calorie fast is the sort of thing you're looking at:

healthunlocked.com/api/redi...

I don't have info on time restricted fasts though.

[jimh111]

Do you mean short term fasting before a blood test or long term low calorie dieting?

[bambuko]

Thank you for the contributions,

and just for clarification:

1) I am not talking about low calorie diets, I am talking about fasting.

These are two different things!

2) I am not concerned about doctor diagnosing (or not) as the result of fasting,

or fasting at different times.

I have Hashimoto's and hypothyroidism diagnosed 15 years ago and don't need tricks to get my GP to prescribe

although I understand that this info might be useful to some.

3) I am interested in the effects of fasting on performance of thyroid, particularly in patients with Hashimoto.

[Cooper27 in reply to bambuko]

Some do follow very low calorie diets as a type of fasting (e.g. the fast 800, 5:2 are considered types of fast), which is why we're checking.

I have heard through various video resources that fasting (your definition) does also reduce T3 levels (these videos were all trying to explain why lowered T3 is good for us), and you will find plenty of discussion on the topic of you Google it. I do think it would depend on the length of time you were doing as to how much the impact would be. (I'm aware the last part is opinion, which I know you hadn't wanted, sorry )

[Hypopotamus]

The only factual information that you can get is by trying it and seeing how it affects you.

[Marymary7]

I fasted as a teen for a week. Have since read that completely fasting can trigger thyroid trouble. Don't have the reference.

[Hidden]

Hey, boostthyroid.com/blog/2018/... this one has a lot of references to research studies below the article. However, the best is to check ResearchGate or even use Google, I have typed in "fasting hashimotos studies" and got loads of stuff.

[Lora7again]

I never fast because it makes me feel ill. I also think the body goes into starvation mode and having researched thyroid disease I found out a lot of people who are from Irish descent have thyroid problems because of the potato famine. I am half Irish btw.

irishcentral.com/roots/hist...

[Cooper27 in reply to Lora7again]

This is an interesting idea, as the line that my genetic predisposition to hashimotos comes down does trace back to Ireland. Is the theory that famine changes our genes somehow?

[Lora7again in reply to Cooper27]

I also heard that a lot of people in the US who are descendants of the American Indians have thyroid disease because they were also starving years ago. Actually I can see the article I posted a link to mentions that as well.

[Cooper27 in reply to Lora7again]

I wonder what impact things like the war had on various countries too, although that'll take me down a rabbit hole regarding survivors from prison camps and how their descendants are affected today.