Carbs & Thyroid Health – Episode 27

Dr. R’s Fast Facts

  • Carbs and Your Thyroid

    • Some diets that lead to weight loss also cause a decrease in thyroid hormone
      • Low carb/calorie diets cause an adaptive/transient decrease in T3 that does not damage your thyroid gland and may help with body composition
      • Carbs seem to have the strongest effect on thyroid levels
    • If your thyroid hormone levels are within normal lab values, either from medication or naturally, and you don’t feel well you should investigate the underlying cause
    • Lab values for hypothyroid
      • TSH consistently high
        • Above 2.5-3 through 6-8, debated.
      • Free T4 consistently low
        • Below 0.8
      • If TSH is high and free T4 is normal – decision for HRT is made on case by case basis; aka you are in the grey area
    • Common issues
      • Diet, sleep and lifestyle
      • Inflammation, often digestive. Digestive infections or dysbiosis (SIBO, candida, H. Pylroi, viruses)…
      • Female hormone imbalances
      • Adrenal fatigue
    • How might some be too low carb for too long?
      • How to know you are too low carb?
        • Paradoxically elevated blood sugar and cholesterol levels
        • Fatigue, carb cravings, brain fog, irritability, GI distress, cold hands/feet, insomnia, muscle loss, low libido or testosterone.
          • Slowly ramp up and see if these problems disappear
    • But if you your carbs are too high, you may notice:
      • High blood sugar levels on blood work
      • Fatigue
      • Weight gain
      • Carb cravings
      • Bloating, gas, constipation and/or loose stools

Dr. Ruscio finishes tackling a listener question in the second part of this two part series on thyroid and podcast-artwork newweight loss. In this episode, he delves into how carbohydrate levels can affect thyroid function and weight loss.

Recap of part 1…..1:20
Listener question…..3:08
Fast Facts…..4:40
Low carbohydrate diets and thyroid function…..17:26
Infections, inflammation and thyroid function…..24:30
Reverse T3…..29:47
Low carbohydrate diets without calorie restriction…..35:12
Episode wrap-up…..36:46


  1. (1:20) Thyroid & Weight Loss Part 1 podcast link – NEED LINK ONCE POSTED
  2. (2:28) Susan’s blog post – “Sorry, There is NO Magic Pill or Quick Fix!!”
  3. (4:40) Carbohydrate restriction most likely has strongest impact on T3 levels
    1. Trusted SourcePubMedGo to source
    2. Trusted SourcePubMedGo to source
  4. (4:40) One review study compared a week on low carb versus normal carb diets and verified that those on low carb had lower T3
  5. (18:14) (20:59) The decrease in T3/rT3 tends to reverse itself after 2 weeks and by 4 weeks are almost back to baseline levels
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  6. (35:12) Type II diabetics were fed normal calorie diets consisting of a low carb or control diet for 5 weeks Trusted SourcePubMedGo to source

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Thyroid Health with Susan McCauley

Welcome to Dr. Ruscio Radio, discussing the cutting edge of health, nutrition, and functional medicine. To make sure you’re up today on this and other important topics, visit and sign up to receive weekly updates. That’s

The following discussion is for educational purposes only, and is not intended to diagnose or treat any disease. Please do not apply any of this information without first speaking to your doctor.

Now, let’s head to the show!

Dr. Michael Ruscio: Hey, folks. Welcome to Dr. Ruscio Radio. This is Dr. Ruscio. I am here with the lovely Susan McCauley from Hey, Susan.

Susan McCauley: Hey, Dr. R. What’s going on?

DR: I am excited for Part 2 of this listener question, which was a springboard to talking about thyroid hormone, and weight levels, and also what we will be talking about today, which is more carbs and your thyroid and your weight. So, excited to jump into this second half.

Recap of part 1

SM: So, before I get too off on our Fast Facts that we are going to be doing in the beginning, why don’t you give everybody a quick recap of last podcast, and we will put a link in the show notes as well (1).

DR: So, in our last podcast we discussed and outlined what the literature says about thyroid hormone replacement therapy and what kind of effect that has on people’s weight. And also, what kind of association there is between people that have altered thyroid levels and their weight. And I think there’s probably a few surprises in there for people because oftentimes people blame weight on thyroid problem. That’s not to say that’s not the case, but it’s not as much of a case as maybe it’s stereotyped to be. And also, that getting on thyroid hormone might be a huge, cathartic event toward weight loss. There is some evidence showing favorable outcomes, but nothing that I would consider earth-shattering. I think we discussed anywhere between 3-8 pounds, depending on kind of thyroid hormone used. So, we provide a nice outline of what the different hormones show and what kind of weight loss people can reasonably expect from using those.

SM: And it’s funny because talking about that topic last week and the magic pill that we talked about, prompted me to write an article about that there is no magic pill, and that we need to change more than one thing to get lasting changes. So, it just kind of stuck in my head.

DR: Nice. Well, if you want to include that link in our show notes…(2)

SM: I will do that. It posts this Thursday, so by the time this airs, it will surely be up.

Listener question

SM: So, before we get started on the Fast Facts, I do want to replay the question from last week. So everybody, if you have haven’t yet listened to last week’s podcast – I highly encourage you to – but if you haven’t yet, we are going to replay the question. So here we go:

Listener Question: I am a 25-year-old woman who has trouble losing weight – with a Free T3 of 3.2-3.8. But, ironically, I am less sluggish and can lose weight when my Free T3 is 1.7.

This has happened more than once, so it seems that there may be a correlation. I’ve confirmed Hashimoto’s, so my thought is, is it possible for me to have antibodies to my own Free T3s? I am aware one can have antibodies to thyroid hormone receptor sites, and I’ve also considered the possibility that my fatigue and weight may be secondary to my adrenal fatigue and other issues, and just coincidental to the thyroid fluctuations.

Any thoughts on this would be helpful.

SM: OK, there we go.

DR: So, there it is. And one thing that I wanted to amend from last week’s episode. I know we made a note to make this correction in the show notes, but I believe that I may have mentioned that people can have antibodies to T3. It’s actually (that) people can have antibodies to T4. It is a lab test that is available through Quest. Essentially what this boils down to is some people may feel worse on a natural or desiccated form of thyroid hormone like Naturethroid or Armour. It may be because they are allergic to T4, and so giving them more bio-identical T4 from actual pig thyroid might make them worse. It’s extremely rare; just something I wanted to amend from last episode. But yeah, let’s jump into our fast facts.

Fast Facts

DR: One real quick preface before I do that, because I want to tie in her question to this discussion of carbs and thyroid.

One of the things she’s asking about is her Free T3 levels, and how she essentially feels better when her Free T3 levels are lower (3a Trusted SourcePubMedGo to source) (3b Trusted SourcePubMedGo to source). We are going to detail this in today’s episode, but when go on a calorie reduced or lower-carb diet, you will see Free T3 levels decrease slightly (4).

For a lot of people, of course, those dietary changes will lead them to feel better, to lose weight, to have more energy. That’s happening even though Free T3 has gone down. So, this is maybe a nice prelude to one of the concepts I want to try to get across today – which is, your levels of thyroid hormone are not everything. So, thinking that being at the top of the range is the best spot to be is definitely erroneous.

So, with that let’s jump into the Fast Facts. The first Fast Fact on carbs and your thyroid being at the top end of the normal range of T4 and T3 does not always correlate to improved health. I’ve seen this time-and-time again in the clinic. People that are at the top of the range don’t always feel better than people who are at the bottom end of the range. It’s a misnomer that is circulating out there. So, the thyroid levels in and of themselves are not a 100-percent

predictor to how someone is going to feel. There is a lot of context.

Additionally, some diets that lead to weight loss also cause a decrease in thyroid hormone. Low carb and low-calorie diets can cause an adaptive in transient or decrease in T3 and Free T3 that does not damage your thyroid gland and may actually be helpful because that transient dip in thyroid hormones may be accompanied by the result of those diets, which may be weight loss, improve insulin sensitivity, (and) what have you.

Carbs seem to have the strongest impact on your T3 levels when compared to the other micro nutrients of protein and fat. If your thyroid hormone levels are within normal lab values – either because you were diagnosed hypothyroid and now you are taking medication, and you are in a normal range; or, you just normally have healthy thyroid levels – normal-range thyroid levels – and you still don’t feel well. You should investigate what the underlying cause may be. There are certainly a lot of people that have their thyroid hormone levels in the normal range that have lots of symptoms that look like thyroid symptoms. They are actually the symptom of something else, some inflammatory issue, stress issue, gut issue. People want to think that it’s a thyroid problem in my experience, a lot of times, and they are trying to shove the solution into the thyroid box. A lot of times it’s not that.

Now, here are some lab values to help you sort this out. If your TSH is consistently high – now, TSH is debated in terms of what the upper level cutoff should be. Some say the upper-level cutoff should be 2.5-3. Others say it should be between 6-8.

SM: Wow, I’ve never heard that one.

DR: But one of the things that is debated as the counterpoint to the 2.5-3 camp is, as we age, it may be normal for some of these values to increase. This happens with a lot of other pituitary hormones – it happens with luteinizing hormone in men and women; it happens with FSH in women. So, as our glands age, they become a little bit less responsive to signaling. It’s just part of the breakdown process or the aging process. So, to see some of the signaling hormones – like TSH – go a little bit higher may not be abnormal. Some studies in centenarians – I always mispronounce that word – they in many cases show very elevated levels of TSH, even though they are in very robust health. So, there is some debate there and context issues.

Now, part of that context would be your T4. If you TSH is high, and your T4 is consistently low, that is really starting to firm up true hypothyroidism, right? Let’s say your TSH is a five – some may call that high – but your T$ is normal, then that may not warrant treatment at that point. But, if your T4 is consistently – consistently below .8 – that really firms up the diagnosis of hypothyroid.

Now, if your TSH is high again, and your Free T4 is normal, that’s kind of a gray area, right? You may or may not be hypothyroid, you may or may not need HRT. There are pros and cons here that are important to mention. Sometimes people want to just jump on thyroid hormone because they think that when they do that, their life is going to change dramatically. Rightfully so, it may. And it may be needed. But, there are also a lot of people that get on thyroid hormone, notice little to no improvement, and then they really want to get off thyroid hormone, but they are concerned that, maybe, because ‘I’ve been on it for three years; have I done some kind of damage, and now I can’t get off of it.

SM: And I’ve also seen people who go on it feel good in the beginning and then go back to how they used to feel pretty fast – like within a month or two.

DR: Right, right. So, there is a lot of context here. This occasional paint-by-numbers belief – meaning, if you are above this, you need that; and if you are below this, you need that – it’s not always the case. There is a lot of interpretation here that has to go into this. Again, there are some guidelines on lab values that can help you contextualize this. To truly say you are hypothyroid, in my opinion, you want to consistently be high TSH and low T4. That would tell you that you certainly need to be thyroid hormone. If your TSH is high, but your T4 is normal, that’s a gray area call or case-by-case call. If they are both normal – both TSH and T4…and I am sorry. I should mention: I am referencing Free T4. The value I gave was for Free T4; I think you should track Free T4. I just wanted to clarify that. If both TSH and Free T4 are consistently normal, and you have symptoms of hypothyroidism, there is probably something else happening that is causing those symptoms. Some common issues here: diet – kind of an obvious one; sleep – another sometimes overlooked but very important one; and lifestyle, stress; and then also inflammation, often of the digestive tract. I’ve seen patients be able to literally cut their dose of thyroid medication in half after clearing SIBO. Candida may release certain chemicals that can block thyroid hormone from being able to work. H. Pylori has been shown to increase thyroid autoimmunity. Viruses have been associated with thyroid autoimmunity. Of course, those can all cause inflammation, which can decrease conversion and activation of thyroid hormone. Female hormone imbalance – progesterone helps facilitate some thyroid hormone function; this is part of the reason women are warmer in the second-half of their cycle- the progesterone dominated half of their cycle – the luteal phase, second half. Also, adrenal fatigue – if you are low in some of your stress hormones, that can impair your conversion of T4 to T-3. And if your stress hormones are too high, that can start to shutdown TSH.

So, those are some of the common interfering factors.

The final point of the Fast Facts is how to determine what your carb intact should be. Well, I think the best strategy here is a start on a lower carb type of diet, and then slowly ramp your way up to try to find what you’re carb threshold is or what your carb sweet spot is. So initially, I like to see people go on a controlled carbohydrate, moderate low-carbohydrate diet, maybe somewhere between 50-100 g per day. Give that some time. See what kind of benefits we achieve. And then slowly ramp up – maybe you had 25 g in for a week, maybe two. See how you feel. If you’re feeling a little bit better, add a little bit more in. At some point, if you add too much, you will notice negative symptoms.

So, if you’re too too low on carbs for too long, you may notice you have elevated blood sugar and cholesterol, which can become this paradoxical elevation that we can see when people are too low-carb for too long. It happens infrequently, but I do see maybe one of those cases every three months. You may be fatigued; you may, obviously, have carb cravings; you may have brain fog; irritability; G.I. distress; cold hands and cold feet; insomnia; muscle loss; low libido; low testosterone – all those can happened if you been too low-carb for too long.

So, slowly ramp-up the carbs. If these things start to melt away, it was a carbohydrate problem at the cause – great. But if your carbs are too high, you may also see high blood sugar levels on blood work; you may also see fatigue, weight gain, carb cravings, bloating, gas, constipation, or loose stools. So, there’s a lot of overlapping symptoms, which is while I like the approach of starting low, titrating up, and trying to find out where your ideal threshold is. And again, that is much easier to figure out if the system is clean and healthy. So, if there any other things – inflammatory disorders, infections, lifestyle issues, dietary issues – those have to be addressed because it will eliminate those variables and make it much easier for you to determine what your ideal carbohydrate dose should be.

SM: So before you start the reintroduction, how long would you go with the 50-100 grams? Thirty days, 60 days, two weeks?

DR: I would go at least 30 days…


DR: …on the initial low-carb diet. And then, if someone is feeling really good on that, I would let them ride that wave a little while – two, three, four months. And then, if they get to a point where they’re not feeling as well as they were before, or they are kind of getting a jones for some of these more carb-rich foods, then you start to do the titration upward, and see where they notice they feel best.

SM: And I know sometimes some people recommend cycling carbs. So, instead of doing a titrate up, doing a bolus of carbs like once a week, or after you work out – those kind situations. Would you want to recommend something like that?

DR: Yeah, I am very open to the carbohydrate approach. I guess the recommendation I’m giving is a good step one. And then from there you could do only carbs at night; you could do one large carb meal a week; you could have phases where you go into a more moderate high carbon, and then cycle back to a lower-carb. In think there is some indigenous and ancestral wisdom there, because if you eat with the seasons, higher and lower carbohydrate foods tend to wax and wane with the seasons in a lot of seasonal climates. I think that when you tinker a little bit you will eventually fall into the pattern that works best for you. So yeah, I think it’s an excellent points, Susan.

SM: And eating with the seasons, you really do. In the summer time, you get that fruit in; in the winter, starchy vegetables come in. I would never say high-carb because that’s like lika a standard American diet.

DR: Right.

SM: So when I talk about high carb I am probably 150 grams-a-day at the very most.

DR: Right.

SM: And then, sometimes during the middle of winter it is probably very low-carb.

DR: Sure. Yeah, I think that makes a lot of sense. And I think it’s important for people to listen to her own bodies and find an approach which works best for them, yeah.

Low carbohydrate diets and thyroid function

DR: So, I’m going to elaborate on a few these points. One of the things that I’ll get from people, the questions I’ll get from patients is if I go low-carb, does that damage my thyroid? No, it does not damage your thyroid. We do see what I would call a temporary decrease in your T3 and Free T3 levels, but that’s a metabolic adaptation; that’s your body having a change in its fuel substrate so it’s shifting its metabolism accordingly. We don’t see increases in antibodies, at least in none of the literature that I’ve seen that has been reported. And we see these changes actually start to

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revert themselves fairly quickly. Now, I will include a table (5 Trusted SourcePubMedGo to source) from from one study in particular that tracked different groups of patients that were on low-calorie diets. They were either on a high-protein diet that was low-calorie or a low-carb diet that was low-calorie. They tracked them for two weeks – I am sorry; they tracked them for a month. What they found was at about two weeks, people had this inflection point, where their Free T3 T3 levels were going down. Correspondingly, their reverse T3 levels were going up. So, we are having a slowdown, a decrease of our thyroid function here. At about two weeks, the hit an inflection point where those changes start to reverse with no change in diet whatsoever. This led the researchers to concluded that what may happen – and this is why I call it transient – is a transient decrease in some of your thyroid hormones as your metabolism adapts.

SM: I think conventional wisdom or even not even conventional, even ancestral wisdom, is that if you don’t eat enough carbs. or your diet is too calorically or carb-restricted, you’re slowing your metabolism down and that’s why your hormone levels are going down. So, it’s

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not really the case, then.

DR: I think there definitely is a grain of truth to that, because we do see some of these metabolic changes…or, i should say, some of of these thyroid hormone changes that indicate your metabolism is slowing down. But, and this is why I think it is really important to zoom out in these contexts, people who are going on a restricted-calorie diet will lose weight and see metabolic markers improve. There is likely a very ancestral concept here where we didn’t always have plenty of food. So going through periods of feeding and famine are something that’s probably healthy for our metabolism. I think the fasting renaissance that is happening right now kind of points to that. So, I think these changes are just our body shifting in response to different nutrient availability. It doesn’t mean that we’re damaging our metabolism, within reason, right? If you’re doing 400 calories a day for three months, then your probably going to damage the system.

SM: Right.

DR: These researchers did find that the further you reduce calories, the more pronounced these issues become. In fact…was it the same study or a different study – I think it was a follow-up study actually. The researchers found there may be what is called a choleric threshold of 800 calories.That may be the threshold where these changes really become quite marked. But, as long as you’re above that threshold, there doesn’t seem to be as much of a detriment on thyroid function. It will be transient, but it will be fairly mild, and it will be something that your body will, after about two weeks, will start to bounce back from.


DR: So, does that make sense? Hopefully that makes sense where people will understand that because lab values change when you change your diet, it doesn’t always mean that they are bad a thing.

SM: Right.

DR: It’s kind of like C-reactive protein. You know, let’s pretend we knew very little about the body and exercise, and I say this with all due respect – I think a lot of people know very little about endocrinology and how all these systems interact with one another. So it’s I think of a good analogy: if we knew very little about exercise and exercise physiology, if we notice that when people do a good high-intensity workout – nothing crazy but what we would consider a reasonable workout, they can sometimes have elevated C-reactive protein, an inflammatory marker in their blood the next day. We may all conclude, “Oh jeez, you probably shouldn’t do this workout because it can cause you to be inflamed. And we all know inflammation is really bad.” But, what were not getting there is that is temporary muscle breakdown that is then preceded by muscle strengthening and a lot of metabolic improvements, right?

If we only look at one marker in isolation, we can sometimes really be misled. It’s kind of like the analogy I like to use: you are trying to navigate from California to Massachusetts looking through microscope. It’s going to be very hard; you have to look at the the big picture. Does that analogy…

SM: Yeah, it makes sense. It really make sense. I know that a lot of people use some of these studies are probably the exact same studies to say that women should never eat low-carb, or women should never go on a diet, you knowing, because you’re doing permanent damage to yourself. And so, we really need to take it all on context.

DR: Yes. You know, context is really, really big because, if you are too zoomed in, it is so incredibly easy to be misled. The further I get into my shenanigans in the medical literature with verifying things, concepts that are held to be true, the more I see that when things are incorrect, it’s usually because people are looking at one small part of the puzzle and drawing conclusions from that without having a broader context.


DR: So, absolutely. That part is very, very important.

All right. So, we talked about not damaging your thyroid by doing these diets. Again, that doesn’t mean you if you do 400 calories for four months, you may do some damage. But, if we are talking about a reasonable caloric restriction, or carbohydrate restriction, I see no evidence suggesting that would be deleterious in the long-term.

Infections, inflammation and thyroid function

DR: A couple tidbits in terms of how having some kind of inflammatory issue or infection may impede thyroid function that you may not see on lap work. One example that we’ve talked about is vitamin D. Certain infections and certain gut inflammatory disorders may elevate a metabolite of vitamin D known as calcitriol. There has been some evidence published – I wouldn’t say it’s strong evidence; it’s an area we don’t know a lot about, but this is just to give people one potential mechanism. When this calcitriol, this vitamin D metabolite, goes high, it may block certain hormonal receptors – like receptors for cortisol and receptors for thyoid hormone. This may be someone where all their thyroid tests are smack dab in the middle-of-the-range perfect, and they still have symptoms of hypothyroid. Well, it may be that there is, let’s say, an H. Pylori infection in the stomach that’s causing a lot of inflammation. That inflammation may be throwing off vitamin D metabolism, and that may be causing her cells to be somewhat resistant to the thyroid hormone that’s actually in her body. So that’s one mechanism. Also remember, certain infections can worsen autoimmunity, like we already talked about. And we talked about progesterone and we talked about adrenal fatigue.

Any questions on that so far, Susan. I’m looking at my list of things here.

SM: Let’s dial back to adrenal fatigue or HPA axis dysregulation, because that’s another one that I’ve heard a lot – if you have adrenal fatigue, you’ve got a make sure to get your carbs in.

DR: Right, and there may be some truth that.


DR: Going on a low carb or calorie-restricted diet for someone that has a lot of fatigue issues may be hard, because, like exercise, fasting, or intermittent fasting, or restriction of calories or carbohydrates, can be stressful on the body. But it can be healthy stressor, if the body has enough reserves to recover from it and become stronger, so to speak, right?

SM: Resilience, basically.

DR: Right, so if your resilience is totally drained, then you may not be able to do one of these interventions yet. You may have the focus a little while on healing before you can go lower carb, or before you can even fast, right? One of the things that we recommend for SIBO patients is, once we’ve cleared SIBO and we are trying to prevent SIBO from reoccurring, is trying to practice a four-to-five-hour window in between meals because that stimulates the cleaning wave that helps clean out bacteria overgrowth. But, I always tell patients, “If you can’t go four hours without feeling foggy, tired, or irritable, then don’t do it, because you’re just not there yet.

And so, that happens…that’s a very case-by-case call. But, I should also mentioned that there are a lot of people that will have adrenal fatigue that is coming from a really inflammed and just irritated gut. When these people fast, it takes so much inflammatory load off of their gut, that they feel fantastic.

SM: Um-huh.

DR: So, I guess I would say there I’m very cautious of absolutes.

SM: Exactly. I was just going to say that. Every body really is different, and people have to play around and do the N=1, and find how they feel – what feels right for them. If you’re a woman and intermittent fasting works for you, keep doing it just because they say “Oh my gosh, women shouldn’t intermittent fast.” I do it a few days per week because I like to work out in the morning fasted. So, you know, I do it two-to-three times a week and I feel great.

DR: Right, I agree. I think, if nothing else, one of the things I hope that we’re helping people learn to do is listen a little more to their bodies, and then also be a little bit more cautious when you hear someone speaking or writing with a very strong stance on an issue. Because usually – and I believe I had a quote on this at PaleoFX – ‘Dogmatism can only survive in the presence of ignorance.’ Meaning, you can only feel super, super strong headed about, ‘It’s only this, and it’s only this way,’ if you are really ignorant of the other facts.

SM: Right. And so, if you hear somebody say, “All carbs are bad,’ or, ‘You have to have carbs,’ like these ‘musts’ and ‘shoulds’ and all that. I remember at AHS last year – I don’t know if you want to Denise Minger’s (presentation) when she looked at the spectrum of different diets and how there is kind of magic on either end. It’s, like, the high fat has the magic, and then the high carb low-fat has some magic, and that’s why some of the vegan doctors get such good results – that we can’t just throw the baby out with the bathwater.

DR: Exactly, yep. I totally agree.

Reverse T3

DR: Well, coming back to thyroid here – I love our tangents,though. I gotta tell you.


DR: We have solid tangents, I think.

SM: Yes. So they wouldn’t be quite tangents – maybe just angles?

DR: Yeah, yeah, elaborations.

SM: Yes.

DR: OK, my reverse T3 tangent – this is a little bit of a tangent or elaboration I wanted to go on.

SM: It’s good one because a lot of doctors won’t test it or won’t look at it, but it can mean something in certain instances.

DR: Yes, it can mean something, and it can also mean nothing.

SM: Exactly.

DR: You know, when I first started reading the literature on T3, it’s pretty impressive. But, I like to look at things through the clinical lens, too. That’s why I feel so fortunate that I have my clinical practice where I can stay in tune with the real world, and not just get lost in all the academics. It’s a rough estimate: I would say, maybe ,50 percent of the time, I find that reverse T3 has little-to-no correlation with how someone presents. Part of what I see there is that people are on thyroid hormone and they are really kind of pushing their dose to the high-end of the range. I’ve seen people coming in with lower TSH – sometimes they are off the charts or out of the range low, because of course the more hormone you take, the lower TSH will go – and their T4 has been high, and their T3 has been high, and sometimes even high slightly out of the reference range – and their reverse T3 has also been high. After I saw this a number of times I thought about it…well if you think about it, T4 becomes converted into both T3 and reverse T3. So, if you have a ton of T4, there’s a higher likelihood you’re going to have high levels of both T3 and reverse T3.

SM: It’s the body’s way of dealing with that…

DR: Yeah, yeah.

SM: It’s to metabolize it into reverse T3.

DR: And, I’ve also seen the opposite. I’ve seen when people come back on the low end of the spectrum, their T4 is at the low end of the the normal range or frankly low, and their T3 is at the low end of the range, or frankly low, then their reverse T3 can also come back in very low. You would think that’s good, but it may not be good when you look at the overall context. So, reverse T3 I think can be important. But, I have to say that, if you gave me a limited number of tests, I would ran a TSH and T4 to rule out overt hypothyroidism, and then use the other tests to investigate where there may be an inflammatory issue present in the body that is throwing off thyroid hormone metabolism. And I wouldn’t even get overly wrapped up in T-3 and reverse T3, because they don’t tell you anything about how to fix that problem.

SM: And also with reverse T3, can’t that also be a marker that your body might be under an inordinate amount of stress?

DR: It can. But that’s what’s funny about it – again, in maybe 50 percent of the cases were I would think, ‘Boy, looking at this gal’s presentation, looking at the lab work that we have, I would think reverse T3 would be off the charts. Maybe half the time it is not. So, that’s why, as I’ve been running these full thyroid SAs in conjunction with all the other testing that I do. I think we were sold a little of a bill of goods thinking that the super in-depth thyroid hormone profiles was going to provide all of the answers. It tells you some of stuff about what is going on downstream. But, again, in a lot of cases, fixing that is dependent upon figuring out what other factors I listed a moment ago, are present the body, and throwing those things off.

I’m not saying that this testing is useless. But, a lot of time, clinically it doesn’t really matter to me, because someone will come in and, once we fix the core issues – infection, diet, lifestyle, inflammatory issues – then they feel a ton better. It’s almost irrespective to what’s happening with their T3 and the reverse T3.

So, I know know if that makes a lot of sense, but I think that, as long as you’re in the ballpark for your TSH and your T4 and your T3 – as long as you are in the ballpark there, then if you’re still not feeling well, the problem is probably somewhere else.

SM: Right, and then also, if people do look at something like reverse T3, and it is high, retest. For me personally, I don’t know why did this, but had blood work done the week after I had three cortisone shots in my back. My reverse…everything was normal, but my reverse T3 was through the roof. I retested two months later and it was back to normal. It just had to be my…but injecting corticosteroids into my system…

DR: Right.

SM: …and the inordinate inordinate stress that put on my…having a needle stuck in your spine is very stressful.

DR: Yeah, I…

SM: And it was just my body’s way of processing stuff. And then, next time…and it’s never been out of the range since, so.

DR: Yep, there you go. I agree. It’s very sound clinical judgement that you illustrate there, which is, if a marker comes back looking like it doesn’t fit, then retest. And oftentimes, these things are false or transient elevations, absolute.

Low carbohydrate diets without calorie restriction

DR: So, we talked about the study looking at low calorie diets – and it was either low calorie with low-carb, or a low-calorie standard kind of diet before. I want to pose a question: is there any data with people on normal calorie diets that are low carbohydrate and looking at thyroid function?

SM: I was just going to ask you that – I was like, we talked about calorie-restricted and calorie-restricted low-carb.What about a not calorie-restricted low-carb? What did that do? And here you go, bringing it up!

DR: See, we are in sync. This is good. I was only able to find one study in this regard when I was doing my literature review. It was in Type 2 diabetics that were fed a normal calorie diet that was either low-carb or control for five weeks. The authors found no change in thyroid function. This may reinforce that caloric threshold that we were talking about, which, if you’re over 800 calories, the impact on thyroid hormone may disappear. So, this points in that direction. In terms of studies, we have one study that looked at this – it was in Type 2 diabetics. But, it appears that data shows no appreciable impact on thyroid function – again, maybe because it’s over the theoretical caloric threshold of 800 calories.

Episode wrap-up

DR: All right. We talked about carbohydrate reintroduction…

SM: Uh-huh.

DR: …so just something to keep in mind: I want to reiterate, I usually recommend people start with the lower-carbohydrate diet, but that doesn’t mean that I think everyone needs to be a low-carbohydrate diet forever. It’s just part of the process of starting low and then working your way up. Some people will do better on a higher-or moderate-carb diet. Some people will do better on a lower-carbohydrate diet. It’s important that you work through the process to try to figure out where you fall on that spectrum. And, if no matter what you do, you’re still not feeling well, then you need to get yourself to a good Functional Medicine clinician and try to sort that out.

My office is still accepting patient if anyone is listening and in need of help. But, yes, if you’re doing this and not noticing anything, then there is probably something present that needs to be cleaned up or eradicated in order to heal.

SM: And do you think people should try to correlate their carb intake with their activity levels? So, if people are sedentary and sit at a desk all day and maybe don’t have time to exercise, those maybe should be on the little bit of the lower-carb. And then those that, maybe, get out and walk every day, exercise, lift weights, do sprints or whatever, that they might increase their carbs?

DR: Yes, I think the more active you are, the more carbs you can get away with, definitely. So, on the days you’re more active, throwing a little more carb into the mix would be a good idea. Not good yet, but you have a little bit higher likelihood that it working well for you on those days.

SM: I know that on the weekends, if I have something to do at night, I always makes sure to lift weights and go on a long hike. Then I feel like I can eat whatever I want.

DR: Yeah, I mean it’s…certainly you earn your beer that night or your muffin or whatever it’s going to be ahead of time. I know you are going to be super gluten-free, because I know gluten floors you. Whatever you snack is…

SM: I always say I have to earn my carbs.

DR: Sure.


DR: Well, I think that kind of wraps it up, Susan. Anything that you want to chime in on?

SM: No. I think that was a really good presentation. We can’t reiterate enough – like we talked about, context matters, and we need to look at it on a case-by-case, person-by-person basis, and that the one thing that works for your husband, your next door neighbor, online, your blogger friend, or whatever isn’t always going work for you. And don’t try to fit a square peg into a round hole.

DR: Absolutely. I couldn’t agree.

SM: OK. So, any last-minute words of wisdom?

DR: That’s it. I’m proud of us because this time we actually led with the Fast Facts instead of (like) last episode we literally ended with it.

SM: I told you I wrote it in my notes. I am one of those people – if I write it down, if it gets on my to-do list, if I write it down, if it’s on my calendar, it usually get’s down.

DR: Nice, nice. Well, we are getting there. Good.

SM: OK, everybody. That’s a wrap, and have a great week.

DR: Thanks, guys.

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