when I first came in contact with paleo, everything seemed to indicate that low-carb/zero-carb is the way to go. And I followed those suggestions precisely.
Unfortunately, when liver glycogen is sparse, T4 to T3 conversion is inhibited. So it seems that long term ZC/VLC inevitably leads to hypothyroidism. (To solve this problem actually foods rich in fructose work best for me, e.g. buckwheat honey; It seems fructose is only toxic in case of fully replete liver glycogen stores)
Now I'm really interested, if there's anybody out there who actually does/did strict VLC/ZC for months and didn't experience any thyroid issues (cold hands, lethargy, light-headedness, ...) - or if some of you also developed hypothyroidism.
I've been VLC since 2008 and every time I try to add back carbs it just doesn't work. So I stick to VLC. I feel great and have no thyroid issues.
There is probably much more to it than that.
I see a top thyroid/hormone dr and he took me OFF carbs and keeps me off to heal. It's complicated by insulin resistance too. The IR has pretty much been cleared up, at least on paper. Each time I see the doc he reminds me to avoid carbs.
When I read these comments about LC killing thyroid, they just look backwards. There has to be more to it than just that.
Maybe the ZC/LC diet is failing for some, due to some now-unknown reason that pops up on a blog a year from now and everyone will be all over it. Maybe people are doing LC for dieters and trying to do intense workouts too, and stressing adrenals, which throws off thyroid. Conclusion, LC hurts thyroid!
BS. Over training stresses the system. The thyroid thing gets the attention because it can get noticed first. Now people are looking for this and the confirmation bias will grow. "Overtraining hurts adrenals. LC hurts thyroid (supposedly). I overtrained, but I will blame it on LC/thyroid..."
Are people simply mixing the symptoms and results of over training and calling it "LC hurts thyroid?" For people this happens to that are not training, are they just starving themselves and running out of whatever it is they need to maintain robust hormones? Is it LC or HOW they are doing LC? It is something else? Too many variables.
How many people realized that they were Hypo while on low carb? Perhaps improving the diet allowed you to notice symptoms you had for a while. Food for thought.
It may be problematic to refer to it as actual hypothyroidism since most people get TSH/T4 tested, which will come back normal if your carb/selenium intake is insufficient. If T3 comes back right where you want it, then by all means eat whatever amount of carbs you want.
Personally, I don't need to get a full thyroid panel to know that a waking oral temperature of 95 degrees + feeling uncomfortably cold all day is not gonna happen. I also got sick repeatedly due I'm sure to what is essentially a persistent reverse-fever. That was on 100g of carbs a day. Increasing it beyond 200g increased waking temperature 1.5-2 degrees and I feel warm all day. Same effect occurred back when I started to supp iodide/selenium. These measurements were done for a week before and a week after, so it wasn't a fluke. I suppose I wouldn't have noticed if I lived at a legitimate latitude or had more insulation.
It's all relative though. I'd imagine that the sedentary can get by on very little in the way of carbs with few perceptible effects.
I tested low t3 on a low carb paleo diet when my doc was testing me like crazy to figure out why I wasn't having my period. I had never been tested for thyroid hormones before, so I can't objectively state that my body started having t4 conversion problems at the same time I went low carb, but I certainly never felt the symptoms I now associate with it before I went low carb.
I have no idea what my t3 levels are now that I stuff myself with bananas, rice, potatoes and oranges, but I sure feel good. Oranges and tangerines in particular make me feel happy after I eat them for some reason. :-)
Like Manimal said, I think that anyone who goes on a calorie-reducing diet for any reason, either because they are deliberately reducing calories or naturally reducing them through a low carb diet may see this. Personally I lost weight on a lower carb diet and the weight loss slowed when I initially went higher carb for a few days and then lower carb, but now I believe that it was mostly due to being in winter and being low on D. It is really hard to say with n=1 because it is hard to control all the variables well. I don't buy the idea that only people on low carb diets have trouble with their thyroids. I see TONS of people on traditional CW diets with thyroid problems. Low carb does not have the corner on this!!!!!! The way I prefer to look at it is that people who have disrupted thyroid function often gain weight, this causes them to try to do something about their weight, and they may find that any type of reducing diet results in sub-stellar success until they deal with the real problem. I am really a fan of Dr. Kruse's leptin reset precisely for this reason. He is the only one who has an explanation why paleo, "safe" starch, or low carb diets may not work well for all people all of the time.
I think it is a lot more than carb content that factors in as some have said- I have been DX with what they call tertiary hypothyroidism and I had all the symptoms and same free ts/t4 levels when I was a carb loading competitive swimmer as I did when I was DX. Before now I was playing around a lot with PSMF to lose weight which utterly tanked my hormones and now that I am on a true VLC paleo diet I find my energy levels so much better and temperature great. However, I am also on T3 treatment for it so obviously that helps. My goal now is to get my period back. All of my health issues were pre-paleo or any carb restricting- I actually put myself into remission from lupus when I started with Scwarzbein and then paleo. So moral is- as it usually is- it is entirely dependent on YOUR body which can be a pretty frustrating answer when all you want is to feel better (trust me- I know).
Sorry, I realize this reply is rather late, but I did have thyroid issues, but have managed to resolve them. Iodine supplementation helped some: there was a huge effect at first, but it faded, and still had some symptoms, just not as bad. Ray Peat has an interesting article on gelatin, and adding that in was a major win for thyroid function, and I would say things are now "normal," which is better than most of the people I interact with at work.
I don't know if I can call this hypothyroidism or metabolic slowdown but this symptoms happend to me after this combination: vlc + intense daily workouts + big caloric deficit. Dissapeared soon after eating more protein/fat calories for a day or two (less effective) or after carb up (CKD style - this is what i'm doing right now).
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