by Bill Roberts
Here's everything you need to know about the thyroid, from testing to drugs to the foods to eat for optimal function.
Your thyroid is tricky. Before we get into the details, let's do a quick test. These signs and symptoms could suggest low thyroid:
- Unreasonably difficult fat loss
- Depression
- Intolerance of cold
- Brain fog
- Low body temperature
- Undue fatigue
- Diabetes
- Obesity
- Recent major fat loss
- Chronic pain and/or chronic inflammatory condition.
If you're male and don't have any of these symptoms, I wouldn't bother getting a thyroid test. If you're female, the same is true, except menstrual problems and unusual water retention could be additional reasons to seek a thyroid test.
Over 80% of people without those issues have healthy thyroids. For most, the real concern is iodide intake – or, if relevant, extreme dieting or a high-fat, low-protein diet. Fixing those will be the most valuable takeaway from any nutrition article!
The Basics
While oral dosing of thyroid hormone is beneficial, it can also be very harmful if done incorrectly. Whether for body composition, athletic performance, or health, three things must be true:
- Your cells must be provided with the right raw materials in suitable amounts.
- Your cells must receive signals which work towards optimizing your goals.
- Your genes must function as well as possible. This varies all the time and can be changed.
Too often, one or more of these are missing from a program. Cover the bases, and get better results.
Your Thyroid Needs Iodide
About 12% of Americans are seriously deficient in iodide as measured by urinary analysis. Many more are sub-optimal. So while diet alone can provide good iodide intake, very often, it doesn't. Giving your food choices and iodized salt intake a quick lookover is worth it.
If most of your food is homemade and salted well with iodized salt, you should have good iodine intake already. If not, then you should increase it.
How much iodized salt is needed if it's your principal source of iodide? It takes about 2 grams or about half a teaspoon of iodized salt (about 936 mg sodium) to meet your rock-bottom minimum for iodide consumption. However, about half the time, iodized salt brands don't meet label claim for iodide, so it could take somewhat more.
Generally, fast foods, processed foods, and restaurants don't use iodized salt. "Sea salt" contains little iodide. If a label reads "salt" instead of "iodized salt," it's not iodized.
If you aren't consuming much iodized salt at home, increasing your intake will benefit you. Get 300 mcg of iodide per day, but somewhat more is fine.
How Much Iodized Salt Is Too Much?
Overdosing with iodized salt is unlikely. The NIH recommends 1100 mcg (1.1 mg) of iodide a day as a maximum intake. There's no reason to consume more than this on an ongoing basis and a good reason not to. Too much can cause hypothyroidism.
If using full-potency iodized salt as the sole source of sodium, 0.8 mg iodide/day wouldn't be reached until consuming about 4945 mg sodium/day. This is about a full tablespoon. I like seeing athletes consume about 4000 mg sodium/day.
I'd prefer, however, you limit iodized salt intake to no more than about half a tablespoon per day. There's no reason to push iodide to the extreme. Some iodized salt is short of full potency, so expect some variation. The above range allows for normal variation. It does assume, however, that the salt is added after cooking, not before.
If pregnant, avoid excess iodide intake. That can happen with consumption of seaweed or over-supplementation with iodide.
What Foods Provide Plenty of Iodide?
You could meet a 150 mcg/day requirement by consuming any one of these:
- 2.5 cups of milk, yogurt, or cottage cheese per day
- 2.5 baked potatoes with skin
- 12 eggs
- 13 ounces of shrimp or of "average" saltwater fish
- 13 ounces of turkey
Beef, chicken, pork, rice, most wheat products, fruits, and veggies are too low in iodine to be major sources. Seaweed or kelp are extremely rich but aren't that common America. Also, whey protein concentrate and micellar casein are pretty rich in iodide. It takes only about 80 grams of these proteins to provide 150 mcg iodine.
So if your diet has several of the above foods, you won't need iodized salt or a supplement. But if your diet is mostly beef, chicken, vegetables, pasta, and fruits, then iodized salt or a supplement could be beneficial.
Vitamin and Mineral Supps for Thyroid
Vitamin D deficiency is associated with hypothyroidism and may cause it. There are many benefits to supplementing with Vitamin D at 4000 to 5000 IU/day, including thyroid function. If you're taking, Biotest's D Fix (Buy at Amazon), you're covered.
For minerals, iron deficiency can result in thyroid impairment. If you're male, iron deficiency is fairly unlikely. Generally, men shouldn't supplement with iron unless blood tests prove a need. However, if you're female, iron deficiency is likely to cause thyroid deficiency.
Dieting and Thyroid
Macronutrient and caloric intake strongly affect thyroid output and conversion of T4 to T3. Protein and carbs are stimulatory, while fat does nothing to sustain thyroid output or conversion of T4 to T3. And excessively low caloric intake can be devastating.
How low? Don't go below a daily intake of 12 kcal/day per pound of in-shape body weight. For example, if you weigh 230 and would be in good shape at 200, take 200 and multiply it by 12 to get 2400 cal/day as a minimum.
If fat loss isn't fast enough, increase exercise rather than cut calories further. On a low-carb diet, keep protein high to maintain thyroid function.
Thyroid Signaling
What cells do, and therefore what the body does, depends on the control signals they get. Damaged, confused, or harmful control signals in the body won't get you where you want, and especially not when thyroid signals aren't right. So what does thyroid signaling do? A quick summary:
Inadequate Thyroid Signaling:
- Reduced metabolic rate, by about 25% in many instances
- Reduced expression of genes important to fat metabolism
- Impaired insulin sensitivity
- Reduced expression of genes important to glucose metabolism and transport into muscle
Excessive Thyroid Signaling:
- Increased heart rate, for example +24% from 75 mcg T3/day
- Increased metabolic rate, for example +13% from 75 mcg T3/day
- Increased fat loss
- Increased expression of genes important to fat metabolism
- Increased catabolism of muscle
- Impaired insulin sensitivity, as also occurs with inadequate signaling
- Increased expression of genes important to glucose metabolism and transport into muscle
Factors Impairing Thyroid Signaling
Thyroid levels or signaling can be impaired by stress, depression, low testosterone, low GH, diabetes, obesity, history of major weight loss, chronic pain, or high levels of C-reactive protein, TNF-alpha, IL-1, and IL-6 (all of which are related to inflammation.)
The answer to all of these is to reduce or eliminate these problems. When too many of these things happen, thyroid-related problems are likely, even if doctors say blood tests are normal. This is because levels of thyroid hormones within cells can be impaired by these conditions even when blood levels are normal.
In depression, however, often, the right thyroid treatment can alleviate the problem.
High TSH Promotes Metabolic Disorder and Obesity
TSH itself isn't a thyroid hormone; it's the hormone that tells the thyroid to make thyroid hormone. When the thyroid is responsive, TSH production is moderate. When the thyroid is unresponsive, TSH levels increase in an attempt to compensate.
That could be okay if this yielded good T3 and T4 levels and nothing else happened. But unfortunately, something else does. High TSH signals cells in a way that changes expression of multiple genes, changing their function greatly – in the direction of metabolic disorder and obesity.
Poor thyroid function not only slows metabolism directly due to low stimulation by T3, but changes gene function towards a state where obesity is the equilibrium condition. Some changes occur from low T3 and others from high TSH. Once this occurs, if the changes aren't reversed it's far more difficult to lose fat and have a normal metabolism.
I Had My Thyroid Tested. What Do the Results Mean?
Thyroid panel interpretation can be easy or very hard. It can be easy when you know the right things to focus on and where the situation is either clearly good or clearly a problem. So let's limit ourselves to what's clearly good:
- Free T3: Middle to the upper part of your test's normal range
- Free T4: Middle to the upper part of your test's normal range
- TSH: Preferably no more than 2, even more preferably 1.5 or less
Doctors often omit testing for free T3, but the value really is needed for good diagnosis. Total T3 can be deceptive, as most of the total is inactive. You don't need total T3 or total T4. If the free values are fine then the total values don't matter. Likewise for T3 Uptake and Free Thyroxine Index: you don't need them.
If free T3 is good, then TSH at the lower end is fine or even beneficial. (Assuming thyroid medication isn't being taken.) Overly high TSH generally shows poor thyroid function, requiring abnormally high stimulation to compensate. High TSH has adverse effects of its own on metabolism, working towards causing metabolic disorder.
If test values aren't quite as good as these, there's no sharp transition between "good" and "bad." It becomes a very slowly sliding scale, with different meanings in different situations. If your results are greatly different from the above and if actions can improve those values, they'll be worth taking.
Reverse T3 is an optional test. Most doctors omit it, and usually, that's fine. If you do obtain this value and its ratio with T3 is out of range, there are various possible causes. If you don't suspect any particular health problem, I wouldn't spend the money on a reverse T3 test.
Thyroid Hormone Products
The most commonly available forms are T3, T4, and Armour Thyroid, which contains both T3 and T4.
Importantly, T3 and T4 products don't have high chemical stability. Even the pharmaceutical companies had issues with stability in tablets, and use particular techniques to address this. Expired product is likely to have lost potency, and generic products may not hold potency even up to the expiration date.
Dosing of Pharmaceutical Thyroid Products
Where the concerns aren't symptoms of thyroid deficiency but rather enhancement, the protocol I favor uses these dosing levels:
- Level 1 – Optimizing body function: Morning dosage of 12.5 mcg T3.
- Level 2 – Light cycle: Morning dosage of 12.5 mcg T3, and evening dosage of 50 mcg T4.
- Level 3 – Heavier cycle: Morning and evening doses of 12.5 mcg T3, and daily T4 dose from 50-200 mcg/day.
Positive effect over time at Level 1 can become very significant, yet I know of no instance of any adverse side effect. There's no detectable effect on thyroid function at this dosage. Usage may be continued as long as desired.
Level 2 provides faster fat loss effect, generally without noticeable adverse effect. TSH is reduced but not shut down, and often remains in the normal range.
Level 3 is obviously more intensive. If any substantial increase in heart rate occurs, dose should be reduced. TSH is likely to be low during the cycle.
For Levels 2 and 3, limit the cycle to 8-12 weeks, but duration can be extended past this. There's no exact science on suppression versus amount and duration of use, but extended use at suppressive levels can result in an extended period of only partial recovery.
Can I Adjust the Dose to Get TSH Where I Want?
Absolutely. If TSH is high, lowering it to 1–2 mU/L is often recommended and may be beneficial, though unproven. In my view, it’s worth doing. Alternatively, if the purpose is to elevate free T3 over a long period without driving TSH below normal, TSH could be evaluated and dose could be limited accordingly.
If health is the goal, avoid driving either free T3 or T4 over the high end of the normal ranges, and most preferably would aim for mid-high.
What About Frontloading T4?
How much T4 does your body have in it after taking, say, 100 mcg of T4? Well, if it's your first dose, then about 100 mcg. Simple enough.
But when you're about 6 weeks into taking T4, when you swallow a daily dose there are already about a week's worth of earlier doses still in the body, still active! So the effect of T4 doses will start out being only about 1/7th as strong as will be the case later. Even one or two weeks into the program, the effect will be only partial.
For many drugs with a long duration of action like T4, frontloading is a way to account for this. To promptly get body levels to where they should remain, on Day 1 an extra amount is taken which corresponds to the above buildup. But T4 is a drug you absolutely don't want to overdose. You don't want to take a week's worth of T4 on Day 1 even though, most likely, it's about the correct amount.
A good solution is to double dose T4 during the first four days of use. This brings levels to the steady state in about 5 days instead of a month. T3 is fast acting and absolutely no frontloading compensation should be made. So when using the above schedules for combining T3 and T4, double the T4 in the first four days, but keep T3 the same.
How Much T3 Can I Use?
If using T3 alone, a maximum and entirely sufficient amount is 75 mcg/day. This typically gives substantially elevated heart rate, enough so to limit dose. I don't prefer for dosing to be this high.
100 mcg/day typically greatly accelerates muscle loss and can cause weakness in the gym. Dosing should not be this high. Even 50 mcg/day is ordinarily entirely sufficient to speed fat loss, and is a recommended maximum.
T3-only thyroid cycles are effective for fat loss and can be safe. My preference for combining T4 is not from efficacy, but from consideration of signaling systems in the body. There's a point to the body having T4 present as well as T3. But inclusion of T4 isn't mandatory for bodybuilding results.
Why Not Jack Up Thyroid Dosing Higher?
Increased muscle burning, cardiac stress, and likelihood of impairing insulin sensitivity. I'd recommend more physical work, better attention to diet, and C3G instead. If your fat loss results aren't excellent within the above recommendations, then I'd look at the diet, at increasing physical work done, or adding C3G (sold as Indigo-3G (Buy at Amazon)).
If I Do Only One Thing, What Should It Be?
Evaluate your diet very approximately. There's no need to do any calculations at all. Do the iodine-rich foods in the list make up a major part of your diet? Then there's no need to supplement with iodide or to use iodized salt.
If these foods are fairly light in your diet, then use iodized salt or take an iodine-containing supplement (Buy at Amazon).
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