IF shuts down your thyroid and lowers testosterone?

(Bob M) #1

I was listening to this podcast (it’s also on youtube):


Here’s what they discuss right toward the end about intermittent fasting (IF):

52:02 Fasting can be a stressor on thyroid hormones, testosterone and androgens, increasing reverse T3, shutting down free T3 levels and increasing aromatase enzymes.

This is the first time I have heard of this. They both said they now eat during longer windows and one eats higher carbs and the other eats higher protein.

As someone about to get a complete thyroid test to see what’s happening there, this has me a bit concerned. Ralph Esposito basically says that fasting for a few days (I think) basically shuts down your thyroid. He also discusses a Ramadan study where testosterone decreased and another study of IF where testosterone decreased although muscle mass increased and fat mass decreased. He is a guy who works a lot with people and their testosterone and these studies have him concerned.

Anyone else heard about the thyroid shutting down during fasting or low testosterone during IF?

(Erin Macfarland ) #2

@ctviggen there are a few different takes on this issue- fasting- and possibly eating low carb in general- does tend to decrease t3 specifically (the active form of thyroid), but some people argue this isn’t inherently problematic as the body basically just down regulates the need for “higher” thyroid hormones. One suggestion is that the reference ranges for thyroid levels are based on those consuming a mixed diet, ie running on glucose, so if you are running on fatty acids as your primary fuel source your body apparently doesn’t “need” as much of that active thyroid hormone. Other low carbers increase their carbs a bit occasionally to prevent prolonged dips in thyroid function (as carbs are apparently needed to produce t3 specifically). Women tend to have more of an issue with lowered thyroid hormone production it seems and might benefit from increasing carbs intermittently to address that. For men, testosterone is the bigger issue, and having increased amounts of carbs or just overall energy intake occasionally can help mitigate low levels of thyroid and sex hormones.

(Give me bacon, or give me death.) #3

I suspect that this is the real issue, for both thyroid and testosterone. One reason is that a low-fat diet lowers cholesterol production, and cholesterol is the precursor to a number of vital hormones, including testosterone. (I believe it may also be related to the thyroid hormones, but don’t quote me, I’m writing off the top of my head, here.)

A low-carbohydrate, high-fat diet seems to be able to fix these problems, in any case.

(Bob M) #4

Thank you both. I also realize that he has a You Tube video that seems to discuss this specifically…which means that I’ll never watch it. I can listen to things, on a run or in the car, but I basically never have time for videos.

For me, it’s troubling. I have had to stop fasting in the past because I was getting too cold. Then, I took a ton of iodine, which seemed to help but also hurt. I was no longer cold, but then I had incidents of random anger for no reason (perhaps you saw that on this board, :wink:), and also heart palpitations. I am on two drugs and have cardiomyopathy (and a “left bundle branch block”) and also was doing other things, so it’s impossible to tell what happened.

What I’m experiencing now is lowered heart rates (I think), lowered blood pressure, and I’m getting a bit cold again when I fast (which completely corrects itself once I eat). I’ve even started retaking iodine, though not nearly at the levels I did before, and this might be helping. But in another part of that podcast, he hints that iodine dosing might be problematic.

And, if you really look into the books where people advocate high iodine intake, this is based on practitioners giving iodine to people and finding a benefit, but not on RCTs. And the levels they recommend are based on high-iodine-intake populations, but maybe they just happened to eat a lot of iodine.

Also, I’ve felt at times lately the “need” to eat a few more carbs, where this means more olives, pickles, maybe yogurt (like dessert to me, I always overeat it). The kids were at sleep away camp, and the wife and I went to dinner and had a high carb dinner, and I think I felt better the next day and the next several days.

The problem is that there is no one like me: low carb/keto 5.5 years, taking beta blockers and ACE inhibitors for 6 years, doing IF and longer term fasting for at least 3.5 years, etc.

I’m going to get a full-blown thyroid test done, but the issue will be getting someone who knows about this in light of a keto diet. That may not be possible. The same would be true for testosterone. The Ralph Esposito guy is in NYC, which is not that far from me. But I’m sure a meeting with him would be financially draining.

Maybe I do have to increase carbs a bit. I do that as a normal matter of course (every few months will have a meal or so off keto), but I’ve been stricter lately. I do add some carbs at times, but I’m basically in ketosis the next day (other than my total off meals, but even then sometimes I’m in ketosis the next day). I could do things like yogurt, darker chocolate (I quit this for a while to test lowered oxalate consumption), etc.

I’ll follow up with this.

(Full Metal KETO AF) #5

And I have heard many claims that a Carnivore OMAD diet raises testosterone? Now I’m really confused!


(Michael - When reality fails to meet expectations, the problem is not reality.) #6

Eating it raw in all its bloody glory makes a man a MAN! :drooling_face:


Are you balancing iodine supps with some selenium or getting a source of selenium in your dietl? A few Brazil nuts a day go a long way there.


I’ve heard about it theoretically on various podcasts, but my own experience is the opposite.
I’m 42 years old I usually do 2 meals a day 18:6, usually breakfast and lunch. I do a 5 day water fast every month. I do keto with almost no dairy. I also do several other interventions such as cold baths, sauna, meditation, HIIT, blue light blocking glasses in the evening. I supplement with lion’s mane, ashwaganda and cordycepts (improves testosterone). I do nose-to-tail eating including liver at least once a week. I eat lots of macadamia nuts and brazil nuts (selenium). I eat oysters at least once a week (zink and selenium).

My latest testosterone measurement was 37 nmol/L, where the reference range is 5,7-26 nmol/L.

The year I’ve measured above 20 consistently. (I do blood draws 4 times each year).

I don’t see any thyroid issues. Sure N=1, but still. At least there is great variability. My testosterone went up after 1,5 years of going keto. So perhaps in my case there was an adaptive phase and when the body adjusted I really optimized.

(Give me bacon, or give me death.) #9

That sounds like simply lack of protein, so that’s normal.

There’s good thyroid info floating around, but good luck finding it. It’s not something I’ve bookmarked, sorry. All I really know is that T3 often looks abnormal on keto, but this is not usually a problem, for reasons I forget, but having to do with how T4 is handled differently on keto, or something. Sorry to be so vague. I’ll make a note to keep better track of the info next time I come across it.


Do you mean this one?


(Give me bacon, or give me death.) #11

Nope. But it’s a great read. I’ve bookmarked it. @ctviggen Bob, you should check out this article and see if it makes sense to you.

P.S.–Stacia says hi.

(Bunny) #12

Thyroid Functionality Matrix:

  1. If you have an iodine deficiency[1][2][3][4] don’t eat foods that contain goitrogens especially when it’s raw! (e.g. never eat broccoli to bring up your DIM SUPPORT {women; estradiol} if you have an iodine deficiency?)

  2. Eat more marine life on keto! (…switch out sources of protein i.e. variety? …if not, your metabolism will slow down to a grinding halt and you will get the chills like nobodies {somebodies?} business when you decide to fast extensively or intermittently?)

Problems solved!

It really is that simple! :scream:


[1] https://www.ncbi.nlm.nih.gov/pubmed/8675242

[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1241182/

[3] https://www.ncbi.nlm.nih.gov/pubmed/2419242

[4] https://www.ncbi.nlm.nih.gov/pubmed/1718324

(PJ) #13

Is your #2 bullet point related to #1? Since it lacked the rather extensive references of #1 :smiley:

(I mean there are other and more dense ways of getting iodine/selenium/etc. into your body than having to eat ‘marine life’)

(Bunny) #14

…and I’m sure you’ll provide the references and research to educate us on the subject?

(PJ) #15

LOL, clearly I pissed you off, but it was not intentional. (I have a gift, apparently.) No my point was that I didn’t know if you were saying ‘eat marine life’ BECAUSE it supported your point #1 (which was well explained), OR if there was some other reason for it (not just about iodine) – in which case I’d be interested to know more. If it was only related to #1 then it was a perfectly good point. Except for people who don’t eat sea life (there are many. I know about 2 people out of 20 who like it at all.)

{Pretty sure “iodine is a supplement” won’t need references. ;-)}

Edited to add: my sincere apologies for my clumsy phrasing that gave my post the wrong impression. Sometimes I’m such a doofus.

(Bunny) #16

Sorry didn’t mean to leave the boys out…lol

e.g. 2. ”…Research and studies. But guided and appropriate supplementation may help raise your testosterone levels. One study researched the effects of a magnesium and zinc supplement. It found that men who received 30 milligrams of zinc per day showed increased levels of free testosterone in their bodies. …” …More

BTW: hint, you need more DHA from marine life in the diet for proper thyroid functionality on a low carb or caloric restricted diet not just iodine and selenium, unless you have access to human breast milk?

(PJ) #17

That’s exactly what I was looking for (so “DHA!”).

No my human breastmilk days are long past and it wasn’t for me anyway lol. Though DHA/EPA are in Omega 3 supplements. Perhaps not nearly as much (or as well in context) as actually eating seafood though, I’d agree.


Somewhere in paleo blog land I read about how DHA impacts women’s adipose deposits (creating more hip/thigh fat/pear shape in women lacking it). :pear: And that sometimes for pear-shaped women eating high on the marine/DHA, reducing the DHA helps recomp of excess adipose storage so as to be a more slender pear…?

(Bunny) #19

I do get suspicious that some people may be getting too much land animals in the diet and not enough marine life (DHA/EPA) and that may explain thyroid issues (metabolic slow down)?

But effecting adipose deposits in (pair shaped) women? I would think that is if your eating a lot of sugar (Paleo?) along with it? Maybe?


Maybe so… hadn’t thought of it like that, makes sense. I recall reading in the long comments thread (on Mark’s Daily Apple) longtime paleo women chiming in about after they stopped their longtime DHA supplementing their recomp was finally happening in the lower body.