How Dehydration Hurts Your Thyroid & How Much Water You Should Drink Daily

It still surprises me that there are people out there who don’t drink enough water. 

If you don’t have enough reasons to drink this life-saving substance then I have one more for you: 

Drinking water helps your thyroid do its job. 

You already know that hypothyroidism is bad because it causes symptoms like weight gain, hair loss, fatigue, and so on. 

And, hopefully, you also know that being dehydrated is bad given that about 60% of your body is made up of water (1). 

But did you also know that being dehydrated can make thyroid function worse? 

This is important to understand because drinking water is 100% in your control and something that should never limit thyroid function. 

If you are one of those people who doesn’t drink enough water, let me give you some reasons to go fill up your glass right now: 

Problem #1. Dehydration Impacts Thyroid Hormone Delivery

In states of dehydration, the body will preferentially shunt blood to more vital organs such as the heart and kidneys. 

Yes, blood still makes it to all of your tissues when you are dehydrated, but the amount getting to your peripheral tissues decreases (2), and with it, so does the delivery of thyroid hormone. 

It’s not like all of your cells suddenly go without thyroid hormone when you are dehydrated, but it’s definitely the case that some cells receive less than they would otherwise. 

And less thyroid hormone delivery means less stimulation of those tissues. 

This is not an ideal situation if you are already dealing with thyroid-related problems like hair loss, swelling of the legs, or muscle cramps in tissues far from your heart. 

The good news is that critical tissues like your brain, heart, liver, and kidneys, will get the majority of what they need due to the shunting of blood, but they are, in effect, taking some of what should go to other tissues and using it for themselves. 

This reduction in thyroid hormone delivery is probably not going to be felt by most people unless they already have a thyroid problem. 

But given that you can prevent dehydration by simply drinking more water, there’s no reason to accept decreased thyroid hormone delivery to any tissue. 

Problem #2. Dehydration Impacts Thyroid Hormone-Binding Proteins

In case you didn’t know, 99% of thyroid hormone floating around in your body is bound to proteins (3) and completely inactive. 

This leaves a measly 1% of thyroid hormone free and active and available for use by the body. 

Why does this matter?

Because in states of dehydration, you end up concentrating the proteins found in your blood which are used to transport thyroid hormone. 

This condition, known as hemoconcentration, impacts thyroid function in several ways: 

By making your thyroid lab tests less reliable and less accurate.

When there is less water in your blood (which is what happens when you are dehydrated), your thyroid hormones become concentrated and appear increased when they are tested. 

But the reality is, your thyroid hormones haven’t changed, only the amount of water in your blood. 

Once you rehydrate with more water, your thyroid hormones will then appear to decrease back to normal (4). 

The absolute value of thyroid hormones hasn’t changed, just their concentration based on the water content of your blood. 

Think about adding 1 cup of sugar to 1 cup of water versus adding 1 cup of sugar to 2 cups of water. 

Both glasses of water have 1 cup of sugar but the cup with more water will be less sweet.

Being dehydrated when you get your labs drawn will make your thyroid lab tests look better than they actually are. 

And on top of this, it may actually impact their function as well which brings us to point #2… 

Dehydration may impact the small amount of free thyroid hormone your body has available for use. 

It may seem good that your thyroid hormones appear ‘elevated’ when you are dehydrated but you have to remember that this concentration effect also impacts binding proteins. 

As the concentration of these binding proteins increases, they may now start to bind more thyroid hormone which reduces the amount of free thyroid hormone in your body. 

We already know that less than 1% of thyroid hormones are free and active so reducing this number even further may result in less thyroid hormone activity overall. 

Problem #3. Dehydration Limits Skeletal Muscle Function And Performance

This is a well-known side effect of dehydration and one of the main reasons that bodybuilders are constantly drinking liquids. 

But what does muscle function have to do with your thyroid? 

Quite a bit, actually. 

Your muscles are a major site of thyroid hormone action which means muscle health impacts thyroid health and vice versa. 

When you are dehydrated, and due to changes in plasma osmolarity (5), blood is shunted away from your muscles which decreases thyroid hormone along with it. 

This means you are losing out on a major source of thyroid hormone activity and limiting your caloric burn in the process. 

It also may make the symptoms of muscle weakness and muscle pain worse which is a symptom that roughly 80% of thyroid patients suffer from and is known as hypothyroid myopathy (6). 

In short: 

Adequate hydration means better blood flow to the muscles… 

Which means better thyroid hormone action on the muscles…

Which means better muscle function, energy production, and metabolic burn. 

It’s a win-win for both tissues. 

Problem #4. Dehydration Reduces the Filtering and Elimination of Chemicals That Have Negative Effects on Thyroid Function

I’ve mentioned before that thyroid patients have a hard time eliminating toxic compounds from their bodies. 

Because of this, they are more sensitive to compounds called endocrine-disrupting chemicals or EDCs. 

These EDCs are compounds that we all come into contact with daily and they are known to have anti-thyroid effects (7). 

They interfere with thyroid hormone binding, increase the breakdown of thyroid hormones in the liver, and influence thyroid binding carrier proteins. 

Put simply: they disrupt thyroid function. 

And your kidneys just so happen to be one of the main ways that your body eliminates these harmful compounds. 

If you are dehydrated, less fluid is moving through your kidneys which means these chemicals stay inside of your body longer where they have more opportunities to negatively impact thyroid function. 

Proper hydration, along with sweating and regular bowel movements, ensure that you are capable of eliminating them. 

This all begs the question: 

How Can You Tell If You Need More Water or If You Are Dehydrated?

The most simple way to tell is by looking at the color of your urine. 

If you are dehydrated, your body will attempt to preserve water by eliminating less of it in the kidneys. 

This means you will urinate less frequently and, when you do, the color of your urine will be very dark. 

This isn’t the only way to tell though and other signs include: 

• A sensation of being thirsty
• Dry skin and dry lips
• Dizziness
• Tenting of the skin, especially on the back of the hand
• Dry mouth
• Low blood pressure
• Bad breath
• Reduced skin elasticity
• headache 

Once you’ve determined you need more water the next question you should ask yourself is:  

How Much Water Should I Drink?

And the answer to this question is more complicated than you might think. 

Despite how important water is for every tissue in your body, nobody can tell you how much you should drink each day. 

It sounds crazy but it’s the truth and if you spend any amount of time trying to figure it out you won’t leave with a clear answer. 

The reality is that how much you drink depends primarily on your activity level and your diet but other things can influence this like the use of medications and even certain medical conditions. 

So while I can’t give you an exact amount to drink, I can give you some general guidelines that will help you stay hydrated: 

• First, aim to drink at least 64 ounces of filtered water each day (that’s 8 cups, by the way), but don’t be afraid to push that up to 1 gallon, especially if you are exercising heavily or using a sauna regularly. Plenty of people report positive side effects when drinking 1 gallon of water per day in the form of better skin, more energy, and even better appetite control. 
• Do your best to stay on top of your water intake to avoid ever becoming dehydrated in the first place. In other words, try to avoid the sensation of feeling thirsty. By the time you feel thirsty, you are already behind in your water intake and have to play catch up. 
• Drink the majority of your water before the evening. You want to make sure you do this so you can avoid waking up in the middle of the night to go to the bathroom. 
• Limit your intake of caffeine and alcohol as much as possible. Both of these compounds prevent your body from creating a hormone called ADH which your kidneys use to capture water. Both of these compounds promote dehydration through this mechanism (8).
• Eat plenty of fruits and vegetables. Roughly 20-25% of your daily water intake comes from foods that you eat which represents a significant portion of total water intake. If you struggle to drink water each day then maybe eating your water will work better for you. Plus, eating more fruits and veggies will help you in other ways as well. 
• Drink enough water to see your urine run clear at least once per day. This ensures that you are getting enough water to flush through your kidneys in a short period of time. 

If you can follow these guidelines then you should be able to avoid ever becoming dehydrated in the first place. 

Now the real quest is… 

Will Drinking Water Fix Your Thyroid Problem?

And the answer to that question is no. 

If you have a thyroid condition like hypothyroidism or Hashimoto’s, drinking water will not cure your thyroid problem. 

It’s best to think of your water intake as a preventative measure as opposed to a therapeutic measure. 

Having said that, there are probably plenty of you who are living in a state of chronic underhydration which means, yes, you might see some improvement in your thyroid by drinking more water. 

But for most of you, this is really just something that you should be doing every single day to prevent dehydration from making your thyroid problems worse and interfering with your thyroid lab tests. 

Drinking more water is important for sure but so is eating the right foods and if you want to learn what foods are best for those with thyroid problems then I’d recommend checking out this article next. 

Now I want to hear from you: 

How is your hydration status? 

Do you feel you are one of the chronically dehydrated people I mentioned or are you really good about getting water in each day? 

Are you planning on drinking more after reading this?

Let me know below!