Low Carb and Thyroid

I'm a 35 year old Finnish woman, living in France for 15 years already! I live in a small medieval village near Chartres (70km from Paris) and am often tempted by the smell of bread from the village's 5 different bakery shops, tough! Anyway, I have always had weight issues, more so during the past 2 years even though I tried dieting and exercising.. Finally I was diagnosed a hypothyroidism with a Hashimoto syndroma meaning my metabolism is really slow and weight loss is difficult. I got a hormonal treatment and started cutting carbs, on my own, 2 months ago.

I just finished reading your book (the one about giving up low-fat diet and losing weight) and was glad to find new reasons to continue my low carb diet, besides the fact that I feel so much better (more energy, not hungry all the time etc.). You discussed thyroid problems in your book, but I'd like to know if there is some data out there about the benefits of low carb diets with regard to thyroid problems? Or, will all my efforts to lose weight be vain no matter what, since my thyroid is so slow?

I would really appreciate your answer, I've tried googleing this but haven't found any strikes.

And thank you so much for your book, it may very well be THE book that changed my life (I'm already thinking about starting a new sport: running!)

Kind regards,

Yikes. I am not a doctor, nor do I play one on television. However, I am a hypothyroid who eats a low carb diet. What follows, then, is a combination of stuff I've read and my personal experience.

First of all, I should state that I was diagnosed hypothyroid a couple of years after going low carb. You can take what you like from that; I've read one or two people suggesting that a low carb diet causes hypothyroidism. In my case, my mother was a hypothyroid, and I've read a great deal that convinces me that this predisposes me to the problem, and of course millions of people who have never eaten a low carb diet in their lives are hypothyroid.

I have also read that major weight loss in general can trip the "hypothyroid" switch, so to speak; that downregulation of thyroid may be one of the ways the body defends itself against the perceived danger of weight loss. I wish I could find that article; I would link to it, but my google-fu seems to be failing me. If this is true, the question then becomes "Which is more dangerous, the sequelae of obesity/hyperinsulinemia, or the sequelae of hypothyroidism?" Since my thyroid has proven pretty simple to treat, I'm predisposed to the latter, but I am aware that serious ignorance on the part of doctors regarding thyroid treatment abounds. I'm lucky enough to have a great doctor.

(Ah. I did find this: Effect of obesity and starvation on thyroid hormone, growth hormone, and cortisol secretion, a study indicating that low calorie diets cause thyroid trouble.)

Dr. William Davis, of Heart Scan Blog, is a cardiologist who has found that hypothyroidism is rampant among his heart patients, and that correcting it helps dramatically with cardiovascular health. He spoke on the low carb cruise last spring, and stated that he's convinced some unidentified environmental factor is causing an increase in thyroid problems. There is speculation that fluoride can cause hypothyroidism; if this is the case fluoridated water may be doing a great deal of harm.

Anyway, you're already hypothyroid, so let's go from there.

Pay attention to your body! You feel far better, less hungry and more energetic; that should be telling you something. Anything that gives a hypothyroid more energy is to be cherished and encouraged.

Make sure your doctor is testing not only your TSH, but your free T3 and free T4. I don't know how it goes in Europe, but over here many doctors rely solely on TSH, which yields very little information about how much active thyroid hormone -- T3 -- is actually getting to your tissues. I take Armour dessicated thyroid instead of Synthroid, because it contains all of the thyroid hormones, while Synthroid is only T4. That's fine if your body efficiently converts the inactive T4 to T3, the active form, but if it doesn't you'll still have all the symptoms of hypothyroidism, including trouble losing weight (not to mention an increased risk of heart disease), while your TSH tests read stone normal.

It is clear that hypothyroids also tend to be insulin resistant, have high blood fats, and in general have the symptoms of metabolic syndrome. To me, this says that they need to be on a low carbohydrate diet. However, there has been very little research done regarding low carbohydrate diets and hypothyroidism. I can tell you that Dr. Davis very much advocates a low carbohydrate diet, and especially the total elimination of wheat and corn. His adamant speaking and writing about wheat have influenced me; I now rarely eat even low carb tortillas or breads.

Mary Shomon, who has the distinction of sort of being to hypothyroidism what I am to low carb dieting -- a person whose own struggles and experiences with a given health issue led her to learn all she could and start writing about it -- advocates carb restriction for hypothyroids, though she feels caloric restriction may also be in order. Her Thyroid Diet focuses more on glycemic index/load than total carb restriction. I gain weight on such a diet, and don't feel as well as I do on a very low carb diet, no more than, say, 40-50 grams per day.

Interesting personal note: I have recently increased my iodine intake, going from one kelp tablet per day to two. I also added tyrosine (an amino acid) to my daily supplement intake, because it can increase dopamine and norepinephrine in the brain, improving mood and lessening appetite. I also got back to taking selenium, which I'd run out of. Within several weeks, I found myself speedy as heck -- irritable, snappish, having trouble sleeping again (I have a sleep disorder, but had it well under control,) and even finding my heart racing. I recognized all of this as possible symptoms of hyperthyroidism, and realized -- dopey me -- that these three things are the main constituents of thyroid hormones. I cut back just a teeny bit on my thyroid dosage (with my doctor's knowledge, of course), and felt much better.

(To be specific: I was on 90 mgs of Armour thyroid, which due to tablet sizes, I got by taking one 30 mg and one 60 mg tablet. I started cutting the 30 mg in half using a pill splitter, dropping my dose to 75 mgs. This actually left me a little tired and light-headed -- hypothyroid symptoms. So I started taking 3/4 of the 30, putting me at a total of 82 mgs per day. Right now this feels right. However, my doctor raises my dose in the autumn; we find it helps my Seasonal Affective Disorder.)

This tells me that some of you can probably improve your own thyroid function by taking these three, but be aware that you're playing with a powerful hormone. If you start getting those speedy symptoms (for me the snappishness -- I was just angry at everything, not a pleasant feeling -- was the most glaring), pay attention. But if you're subclinically hypothyroid, you may find that these three help you lose weight by improving your thyroid function. May make you feel better, too. Dr. Davis writes that he has seen medicated hypothyroids reduce their need for medication simply through iodine supplementation.

One other note: Be aware that soy is notorious for causing thyroid problems, and it's a popular ingredient in low carb specialty products and "health" foods. I don't shun soy entirely, but I do minimize my exposure; I get far less than a serving per week -- usually less than a serving per month.

That's most of what I can tell you, except to be aware that, here in the States at least, it is vital for hypothyroids to become educated and fiercely advocate for their own health. Take a look at Stop The Thyroid Madness and Mary Shomon's About.com pages and also her Thyroid Info site for useful information.

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Hypothyroid and low-carb

Ten years ago, after two years of hypothyroid symptoms (including a three stone weight gain) a blood test revealed I was hypothyroid - but my GP still refused to give me thyroxine and I had a two month wait to see an endocrinologist. Through my own research I realised a link between thyroid function and insulin resistance, discovered Hold the Toast and Atkins - and lost two stone before I even got to see the endocrinologist. And my incredibly painful rosacea cleared up. My daughter controls her endometriosis following a low-carb life - and I have a beautiful five-month old grandson to show for it.

LC & hypothyroidism

Great answer!

Count me as another who was diagnosed hypothyroid (4 years ago) after switching to a LC way of eating (6.5 years ago). In fact, it was a newsletter of *yours* that mentioned your struggle with hypothyroidism one winter that alerted me that my symptoms might be hypothyroidism.

There is some evidence that weight loss diets can reduce thyroid function. Apparently even Dr. Atkins has said the same. One factor might be lack of good healthy fat, which I think is a powerful signal to the body that starvation is a danger - even LC eaters sometimes restrict fat in favor of protein. But that's just my "back of the envelope" calculation at this point.

You mention soy as a possible thyroid inhibitor and I'd like to emphasize another: gluten.

Gluten is often added to conventional whole grains baked products to boost the protein content, lower the carb content, and extend shelf life. I've never seen a reduced bakery product that didn't have added gluten. Gluten gives whole grain breads a soft and airy texture (instead of brick-like). Huge numbers of processed food items that don't even appear to be very wheaty in fact contain gluten ingredients. Gluten is a cheap protein additive so it is used widely in processed foods - it's hard to avoid unless one adopts reads labels, avoids processed foods, and focusses on Real Food (made from scratch).

When I first adopted LC eating I focussed too much on carb counts and not enough on Real Foods. Being a carb-lover, I didn't want to give up bread; I wanted to have my cake and eat it too. I frequently purchased and ate LC breads, which are nearly always made with added soy flour and added wheat gluten. In fact, while I was gaining weight prior to adopting LC, I was baking a lot of bread in a home bread machine and the recipes used added wheat gluten to boost dough rising performance.

So for several years before LC and for at least 2 years after LC, not only was I consuming soy in a number of manufactured products, but I was bombarding my body with a LOT of wheat gluten, both bought and homemade. Almost two years ago I tested for gluten antibodies and have learned my immune system reacts to soy and gluten by producing antibodies against them (www.enterolab.com). I also was positive for anti-tissuetransglutaminase antibodies which can destroy my own tissues. And I have two copies of genes that predispose to gluten sensitivity. I don't appear to be celiac, but rather am gluten sensitive (I don't get severe gastrointestinal symptoms from ingesting gluten, but the theory is the gluten can disrupt non-GI tissue function elsewhere - like the thyroid, joints, beta cells, nerves, and so on). Now that I am gluten-free, when I have been exposed to gluten, sometimes (but not always) I have pain and GI symptoms. When I was always eating gluten, I thought the frequent heartburn and indigestion was normal.

I'm also another who doesn't feel well with synthetic T4 only. I've seen several doctors over the past few years to try to get the best treatment (some won't prescribe T3 or natural thyroid hormone) and have tried a number of different thyroid hormone replacement variations. I now am treated by a doctor who focusses as much on "wellness" as on "sickness", which has been a huge improvement. Taking a combo of synthetic T4 and T3 worked ok, but IMO, I do best taking when taking an appropriate dose of Naturethroid (similar to Armour), which is complete thyroid (contains T1, T2, T3, and T4 hormones). I definitely need to have T3 with my T4. I also seem to need a slightly higher dose as days grow shorter (into fall and winter), with a slight dose reduction in spring/summer when the days are longer. I live in mild So California now, so it isn't a temperature thing; I'm pretty sure it's the light.

Seasonal thyroid changes

I, too, increase my thyroid in the winter and cut back in summer. Indeed, there is speculation that reduced thyroid production is one of the mechanisms behind SAD. Also why we gain easily in the fall and lose at least somewhat more easily come spring.

I'm convinced we were meant for semi-hibernation.

Very Interesting

Perhaps we were separated at birth ?? I can relate to so much of this - there are several issues here of which I was unaware of and will research further. I too feel better on the Armour thryoid medication. And I will look into the other supplements you have added (although I hate taking handfulls of pills). I appreciate this wealth of information Thank you
Sandy Lee
(and oh year my birthday is in October too!!!)


I know it's only one bit of data but I have been low carbing for 7 years. Early this year I started feeling terrible, exhausted and generally yucky. Over a period of about 4 months I lost 50 pounds without really trying. After a diagnosis of a gall stone I changed GPs to get an okay for surgery (my old one had moved away). He immediately spotted my high heart rate that along with the weight loss suggested that I had hyperthyroidism. I doubt there is any LC causation for either hypo or hyper, can't imagine it causing both. I am 74 years old and suspect it's just one of those things that happen more often as one ages. I have seen the endocrinologist once, she immediately put me on Methimazole to reduce the thyroid and Propranalol to lower the heart rate which quickly fell from around 100 to the low 70s. I feel much better and my weight has stabilized (though I could stand to lose a bit more). She took blood to do a full panel when I saw her and I will have another appointment in a couple of weeks to find out more about what is going on. GP also says I don't need the gall bladder surgery.

It's interesting that both hypo and hyper make one tired, the hyper wears you out because your metabolism is running so fast.