Hypothyroid has been covered to death before. I’m particularly fond of The Healthy Skeptic’s coverage – check out Chris Kresser’s ongoing series  (possibly before you read on) for some great information on the thyroid. Carnivorous Danny Roddy did a good piece  on it last year as well. As such, I won’t be redoing or rehashing an “intro to thyroid.” Instead, I’ll give a brief overview and then discuss why I think some of us may be looking at thyroid “dysfunction” in the wrong light.
The thyroid is a complicated little bugger wielding a lot of influence over the metabolism, and it seems like just about anything has been fingered as a trigger of its dysfunction. Lack of carbs in the diet, too few calories, too much iodine , too little iodine, too many grains , intermittent fasting , excessive cortisol , and multiple other factors have gotten the blame. Unraveling the multiple potential triggers for its dysfunction can be tough. But is dysfunction always the right way to describe a slight reduction in thyroid hormones? I’m not so sure.
In clinical cases of hypothyroidism, elevated levels of thyroid stimulating hormone (TSH) indicate that the thyroid is no longer producing enough thyroxine (T4) and triiodothyronine (T3). Further tests of T4 and sometimes T3 can confirm it. Metabolic rates slow down. People gain weight and can’t ever seem to get enough sleep or get warm enough, especially in the extremities. Blood lipids increase and often worsen, and some cases even develop into emotional depression. If hypothyroidism gets really extreme and is allowed to progress unabated, hair loss, impaired memory/cognition, face puffiness, and numbness of the arms and legs can occur. Now, don’t get me wrong. These are terrible, frustrating symptoms for someone to deal with, and clinical hypothyroidism is a real problem, one that can be mitigated or treated with pharmaceuticals. I’m not trying to discount that. In fact, let’s take a look at the most common form of hypothyroidism: Hashimoto’s thyroiditis, an autoimmune disease responsible for around 90% of hypothyroid cases in the United States . People with Hashimoto’s produce thyroid tissue antibodies that compel the immune system to wage war on their thyroid glands, destroying the thyroid itself. Without a thyroid gland, you can’t produce thyroid hormone. Without thyroid hormone, you’ve got hypothyroidism. That’s a serious problem.
(Side note that probably deserves more attention: Whenever I hear the word “autoimmune,” I immediately think of gluten , lectins , saponins and other gut irritants. I’m inherently suspicious of their role in human health, but when it comes to autoimmune diseases, I’m downright accusatory. Sure enough, Hashimoto’s thyroiditis patients are more likely to be celiacs , and abstaining from gluten for the purpose of reducing anti-gliadin antibodies also seems to reduce thyroid-specific antibodies . As Chris mentions , Hashimoto’s appears to merely be a part of a wider “polyendocrine autoimmune pattern” characterized by the presence of antibodies for multiple tissues and enzymes in the body.)
But what if “mild” hypothyroidism isn’t such a bad thing for those of us without Hashimoto’s? It manifests as a down regulated metabolism, a depressed energy output – a slowing down of sorts. Everything slows. What if slowing things down for a bit actually helps increase health?
As for general complaints about hypothyroidism due to some lab results, I’m always wary of folks determining their sense of health based on how their numbers compare to “normal” test results (remember my blood pressure experience? ). Everything is relative; your numbers are being compared to millions of other numbers derived from a population eating the SAD, leading stressful lives, and following the modern, misleading CW . Is this population normal? Sure, using the strict definition. Is it healthy? No, and I think that calls into question the validity of comparing your numbers to theirs and using that comparison to determine which drugs to take.
You may have heard of the calorie restriction set, with their CRONometers and their fervent desire for life extension. It’s not a lifestyle I’m necessarily keen on, but the concept of calorie restriction as a life extension technique does have merit – plenty of studies show extended life spans in CR animal models, like monkeys , rodents , worms , and flies (a pretty diverse cross-section of life, I’d say) – and it’s always smart to pick and choose from what works and what does not, regardless of the source (this isn’t religion, folks, and dogmatic purity  doesn’t matter when you’re just trying to get healthy and live well). Caloric restriction lowers circulating T3, which is the active, “potent” thyroid hormone that (for our intents and purposes) controls the metabolic rate. Low T3, lower metabolism, potentially greater longevity (since you aren’t “burning” as bright, so to speak). All good, right?
Sort of. Those rats, monkeys, and worms were having food withheld. They weren’t consciously deciding to restrict calories, and even though they were living longer, disease-free lives, they began to show signs of clinical depression. Humans do the same, as anyone who’s examined the results of Ancel Keys’ starvation study  or dealt with a hungry, cranky spouse can attest. Nobody wants to restrict calories.
Intermittent fasting has been proposed as an effective way to get the benefits of caloric restriction without the actual restriction. Intermittent fasting  certainly has some similar effects on the body. Like CR, IF reduces circulating T3  – but T4 normalizes . Like CR, IF likely improves age-related degradations in worms , rodents , and humans . It has the effect of spontaneously lowering caloric intake without much effort (eating Primal has the same effect on satiety), and many of the benefits attributed to both CR and IF are associated with thyroid hormone levels that approach “mild hypothyroidism.” Hyperthyroidism, on the other hand, has the potential to shorten lifespan .
I’m just speculating here. Others, like Nora Gedgaudas, have suggested that a mildly hypothyroidic state might actually be physiologically “normal” and optimum for longevity. It makes sense, intuitively.
In the end, I’m all about subjective results. How are you feeling? Are you gaining weight? Are you fatigued? Or are your lab numbers just telling you (or your doctor) that you should be experiencing these symptoms? Listen to your body. If you’re experiencing the clinical symptoms of hypothyroidism, if you’re falling asleep at your desk and gaining weight and just generally feeling like crap, you’d listen to your body and get your thyroid checked, wouldn’t you? Just make sure you don’t ignore your body if it’s telling you good things, too, and don’t let some mildly “irregular” numbers override your intuitive sense of well-being.