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Here’s How Thyroid Levels Affect Your Metabolism – And Your Health

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What does the thyroid do? Your thyroid – a small gland that sits at the front of your neck – keeps your metabolism running smoothly. Because your thyroid controls so much of your metabolism, it must function properly for you to remain healthy and feeling good.

The thyroid gland regulates metabolism by releasing hormones into the bloodstream, so by measuring how much of these hormones you have and checking your thyroid function (do this at home with the at-home Thyroid Test), you may discover if there’s something wrong with your metabolism.

In many cases, people will experience thyroid weight gain or weight loss problems when there is an imbalance with their hormones due to a thyroid disorder. Our at-home testing options let you check your body’s metabolism hormones and thyroid function so you can learn if you have a hormonal imbalance.

The thyroid gland is quite a unique body part. For example, thyroid cells are the only cells in your body that can take up iodine – a rare element – in large amounts and build hormones with that iodine. These hormones are then released into the bloodstream. But when these hormones aren’t produced at a normal level, you may experience thyroid weight loss or weight gain—or other symptoms.

More specifically, the thyroid gland produces two hormones. These hormones are known as T3 and T4. Although the thyroid gland makes more T4, the T3 hormone is more potent. Most thyroid hormones bind to other molecules in your blood – and are thus inactive – but some of these hormones jostle about freely in your blood, and can thus get work done by themselves.

If the thyroid gland regulates your metabolism, then what is it that controls the thyroid gland itself? The answer to that is the pituitary gland. When the pituitary gland “senses” that your body’s thyroid hormone levels need to be adjusted, it sends a hormonal signal to the thyroid gland in the form of thyroid-stimulating hormone (known as “TSH”). So what does high TSH mean? Elevated TSH levels in your blood typically mean that your thyroid isn’t pumping out enough thyroid hormones.

There are also some molecules that suggest your thyroid gland isn’t functioning correctly. These molecules are called “thyroid peroxidase antibodies” – or TPOab. The presence of these thyroid antibodies points to the possibility of an autoimmune disorder that’s impairing your thyroid’s function.

Thyroid Hormones: Metabolism and Functions

Thyroid hormones are essential to your metabolism. In fact, many of your body’s cells have thyroid hormone receptors, which means that thyroid hormones can influence your metabolism in a host of ways.

Take fat metabolism, for example. Thyroid hormones help your body burn fat – providing you with more energy. As a result of this effect on fat metabolism, thyroid hormones bump up your basal metabolic rate (BMR) – which means you’ll be burning off fat even when you’re not physically active.

Thyroid hormones also impact carbohydrate metabolism. For instance, thyroid hormones stimulate the production of glucose (a sugar – which is produced when carbohydrates are broken down – that your body uses for energy). Your brain runs on glucose as its energy source, so if it weren’t for your thyroid hormones, your brain couldn’t function. The result would be a bit like unplugging your computer from its power source – or taking out its battery!

What’s more, thyroid hormones also control your body’s internal temperature, protecting your organs from frosty temperature in the winter or boiling-hot conditions during the summer. In women, thyroid hormones help maintain a regular menstrual cycle – just one more example of the large number of ways thyroid hormones regulate so many aspects of your body.

In short, to feel energized and be healthy, you need optimal thyroid levels. But there’s a catch: you have to have the right amounts of thyroid hormones. When your body doesn’t have the right levels of thyroid hormones, your health falters.

Low Thyroid Hormone Levels

Iodine – frequently found in seawater and seafood – is essential to human health. And if you’re not getting enough iodine in your diet, then you may be putting your health through the gauntlet of hypothyroidism. Hypothyroidism refers to an underactive thyroid – your thyroid gland doesn’t produce enough thyroid hormones. Iodine deficiency may result in hypothyroidism TSH levels (high TSH), but this is not the only possible cause of low thyroid hormone levels. For example, autoimmune disorders – as well as exposure to radiation therapy during cancer treatment – can also lead to hypothyroidism.

Symptoms of low thyroid hormone levels range from the dramatic to the somewhat more subtle. People with hypothyroidism might gain weight rapidly, for example – or find themselves wearily running on fumes all day due to excessive fatigue. Hair loss can also result – and you may be less resistant to cold temperatures. Your skin can also have a cool and dry feel to it. In women, irregular – or even completely absent – menses is another sign of low thyroid hormone levels.

High Thyroid Hormone Levels

Perhaps you’ve been feeling lots of anxiety before an important job interview – and it just doesn’t seem to go away. Well, it could be more than just nerves, since high thyroid levels are known to heighten anxiety.

This is just one example of the consequences of high thyroid hormone levels. Other consequences? Swift weight loss, high blood pressure, and thinning hair – to name a few. When your thyroid hormone levels get too high, you can also experience tremors and an irregular heartbeat – and have a hard time concentrating or sleeping.

As you can see, high thyroid hormone levels can disrupt your health in many different ways – the frightening aftermath of a thyroid gland gone awry. Fortunately, medical researchers and scientists have discovered several different causes of hyperthyroidism (and other common thyroid problems). Autoimmune disorders – such as Graves’ disease – can lead to an overactive thyroid that pumps out too much thyroid hormones (and is associated with reduced levels of thyroid-stimulating hormone). A malfunctioning pituitary gland can likewise coax your thyroid gland into gushing out too much thyroid hormone. Dietary supplements intended for weight loss may also trigger hyperthyroidism TSH levels (low TSH). In some cases, a healthcare provider may prescribe thyroid medication to help rebalance hormone levels in the body.

What Does TSH Level Indicate?

Remember when we were talking about TSH levels? TSH is a hormone released by the pituitary gland that stimulates the thyroid gland to produce more thyroid hormones. If your TSH levels are too low, then you may have an overactive thyroid gland – with your body producing too much thyroid hormones, which can lead changes in your body’s metabolism. (A low TSH value could also mean that you’re taking too much thyroid hormone supplementation or medication.) And if you have high TSH levels, then the reverse is true: you may have an underactive thyroid gland that’s not producing enough hormones. (Related: Hypothyroidism vs. hyperthyroidism)

What TPOab Antibody Levels Indicate

When TPO antibody (TPOab) levels are found in profuse amounts in your blood, it’s a red flag that your thyroid gland may be malfunctioning because of an autoimmune disorder. Not everyone with high TPOab levels has a badly-working thyroid gland, but elevated levels are commonly seen in individuals with autoimmune thyroid diseases, such as Hashimoto’s thyroiditis.

What You Can Do To Get Healthy Thyroid Hormone Levels

After all this thyroid-hormone-levels-gone-wrong talk, you’d be justified in thinking to yourself, “Okay, so how can I get healthy thyroid hormone levels to help avoid a thyroid problem?”

First, make sure you’re getting the right amount of iodine in your diet (your body can’t make iodine, so it’s got to come from the food you eat). (Related: Foods That Help Thyroid Function)

For men and non-pregnant women, the recommended daily allowance for iodine is 150 micrograms (mcg). For pregnant women, that number rises to 220 mcg per day – and 290 mcg a day for women who are breastfeeding.

If you want to check if you have an underactive thyroid gland (perhaps because you're experiencing signs of primary hypothyroidism)—or if you’re interested in finding out if you have high thyroid levels—getting a thyroid function test can be a good place to start.

Of course, if your thyroid hormone level isn't within a normal range and you may have a thyroid dysfunction, consult with your healthcare provider to learn what solution is best for you to help get your hormone levels back in balance (in some cases, thyroid hormone replacement may be recommended). If you do have a thyroid disorder or thyroid condition, your healthcare provider may recommend ongoing thyroid testing to monitor results of your treatment plan.


Your thyroid gland is a key part of your metabolic health. The hormones released by the thyroid gland regulate your body’s functioning in a stunning variety of ways. But your well-being can slide downhill when your thyroid hormone levels are too high – or too low. If you’re experiencing changes in body weight, hair loss, lethargy, or other symptoms related to a thyroid condition, thyroid function tests can help you check your levels of thyroid hormones to see if they are abnormal.

Testing your thyroid hormone levels with the Everlywell at-home Thyroid Test is an easy, effective way to check on the status of your thyroid—from the comfort of your home. And our at-home Thyroid Test is more than just a TSH test: it measures TSH in addition to the thyroid hormones T3 and T4 (plus TPOab)—giving you a comprehensive, easy way to see if you might have too much or not enough thyroid hormones in your body.

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