Levothyroxine and keto

(Robert Love) #1

Keto is mainly about insulin regulation via diet, right? Today I learned that there are other hormones that affect blood sugar levels (https://en.m.wikipedia.org/wiki/Blood_sugar_regulation). One in particular caught my eye: thyroxine.

Anyone know of studies that explore its role in keto?

Reason i ask: a hypothroiodc on levothyroxine (synthetic thyroxine) is struggling to see results with keto.


I don’t know of specific studies, but there’s lots of people here including me who are having success while being hypothyroid.

Here’s where thyroid issues have been talked about, there’s lots of links in there that could be helpful:



It wold merit further tests re thyroid IMO. T4 only is basically a bit shit when it comes to treating hypo. I would suggest testing antibodies to ascertain if they are Hashis or not and also Free T4 and Free T3. I really get Reverse T3 too. That will give a better picture of what is going on. If the hypo is not being treated properly then that will explain the lack of results. It could have nothing to do with keto. Keto will help with the thyroid but not as much as is needed. More tests please!

(David K) #4

I stopped taking Synthroid after being Keto for a few months and saw a 25 point drop in BG numbers. My Doctor then reran my thyroid numbers and they were perfect.

I am not a Doctor and I don’t play one on TV.
I didn’t stay at a Holiday Inn Express last night.
Past results do not guarantee future performance.
Your mileage may vary.
Professional driver on closed course.

(James storie) #5

I take levothyroxin 175 mcg. I had Grave’s Disease as a teenager (17), I’m now 37. I’ve been keto for 2.25 years, down 43 pounds so far, maybe 20 to go. I lost weight quickly then stalled for what seemed like forever. But weight has begun to move again recently. I did start experimenting with EF. I actually had to lower my dose, down from 200 mcg, it was driving my blood pressure up! Other than that, I haven’t had any problems.

(James storie) #6

Oh yeah, I forgot to mention, because of the Grave’s Disease, I no longer have a thyroid gland. So, hormone replacement is lifetime for me.

(Rhiannon ) #7


(Nicole) #8

I haven’t looked into T4 drugs (or T3/T4) causing higher BG, partially because I’m another who is pretty dependent on my thyroid meds. I am hypothyroid but not diagnosed with hashis. I assume I have it since I have a couple of other AI disorders and I can’t figure out any other reasons that my thyroid stopped working. KWIM?
I take pretty much a full replacement dose of natural desiccated thyroid - 180 mcg at about 160 lbs, and it was just increased by 30mcg a couple of months ago. Even if it does contribute to higher BG, and I do have prediabetes and a very stubborn FBG, I can’t drop that med. :frowning:


Never heard of it increasing BG. You being hypo would be way worse IMO.

(David K) #10

It increased mine, or at least didn’t allow it to come down like it should have on Keto. See my response above.

(Beth) #11

Maybe it’s a reverse relationship than what you’re thinking? That is, maybe your thyroid being out of whack made your BG go up? It doesn’t seem like the meds would do that – well, synthroid may have some fillers that your body doesn’t like, but natural desiccated thyroid? I don’t see how it could. By the way, I have no thyroid at all and I take 97.5mcg of nature-throid.

(David K) #12

I was on Synthroid and had logs of my blood sugar but lost them when the phone they were on died. The only difference between the higher and lower numbers was Synthroid and I had been Keto for about 6 weeks when I stopped taking it. I had also researched it some with Dr. Google. Obviously, N=1.



I had the opposite experience. I was undiagnosed hypothyroid (Hashi’s) for about 5 years. When I was finally diagnosed, my A1C was 5.7, but with treatment (first Levoxyl, now Synthroid), my A1C dropped (and has remained steady) at 5.2. I was eating very low carb the entire time.

I think it’s the flawed thyroid rather than the Rx that can cause high BG. The same happened with my LDL. Undiagnosed, it was elevated, but it slowly came down to a normal level with treatment (Rx).

(Chele Eva Armstrong) #14

Hello! I see you stopped taking Synthroid. I was only slightly low when my naturopath Rx’ed it. I started IF LCHF diet May 21. My heart started fluttering the 2-3 week in . I noticed - When I forgot my pill one day that I felt better. But My Dr had scared me into “Don’t stop taking it!! That could be very bad!”
SO I decided to go to a half dose. But I was still not feeling well so I quit taking it. That was a week ago. No I can’t tell if my fluttering is Keto related or thyroid.

I know I know I need to go get blood done. But I was hoping to get a couple months of IF- LCHF under my belt before doing that.

I have lost 13 pounds and seem to be holding a steady 1 pound a week gone.

I guess I just wanted to ask how you got off your medication? Could the IF LCHF be healing that?


(David K) #15

I went LCHF with a little exercise and that was really it. Just had my thyroid tested a few weeks ago and all was normal.

(Chele Eva Armstrong) #16

Thank you!


Hi, I am new here, but kind of frantic for some ideas. So although this doesn’t improve the conversation, maybe someone has some experience or ideas that might turn me in the right direction. Due to get blood draw and see the doc next week and I’d like to go prepared.

My big problem is that on keto w.o.e., my thyroid symptoms got worse. Much worse. Keto for 6 months, dropped 49 lbs, and I feel fantastic. (I am currently taking levothyr 50 mcg.) But I don’t get the increased energy others report, no, I am more tired. My skin and nails are drier. And the heartbreaking thing is that I am losing my hair at a very, very alarming rate.

Searching the vast ocean of the Internet mostly produced advice to bring back carbs, ask doc for armour dessicated thyroid, or add cytomel T3. None seemed to have strong science backup.

I don’t want to add carbs back in.

And t3? Not so fast…

Recent article by Dr Phinney discussing a theory on the mechanism of lower T3 with keto:


And your website had a fantastic, tough going for me, 2014 literature review article on lower T3 as an adaptation to preserve lean, muscle, tissue:

Thank goodness for this article and for Dr Phinney’s! I will not be asking the doc for added T3.

I read that hair loss is one of the listed side effects of levothyroxine. Could it be that, I wonder, that my dose is now too high? Can levothyr cause the very hypothyroid symptoms it is supposed to ameliorate?


(James storie) #18

I have had to lower my dosage. Only once so far, keto 3 years. But, I don’t have a thyroid (radioactive iodine treatment), so I don’t have any competition for the levothyroxin. No hair loss

(Constance Spurling) #19

Hi. I just wondered how you progressed, mevysmoon. I’m experiencing the same thing you’ve described here.

(Melissa Caldwell) #20

I am hypothyroid since birth. I take levothyroxine-137 mcg daily plus an extra half on Sunday morning. I have it checked every six months at least but have been checked more often and dosage changed slightly because I can’t get it regulated for the past couple of years. I have only been on keto a month and have lost about 15 lbs and 5 inches off my waist. I haven’t gotten any ketone strips but just eating as close as possible to keto WOE as I can. I know the weight loss may be slower due to my HT problem. Cutting out the sugar helped tremendously with the cravings for me. I follow cooking keto with Kristie on YouTube a lot. Hope this helped.