Is Keto the Best Diet for Hypothyroidism?

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Science Based

Written by Amy Myers, MD

The ketogenic (or “keto”) diet is a low-carb diet emphasizing high-fat intake and largely limiting carbohydrates. Historically, the keto diet was developed as an alternative treatment for epileptic children and has been proven to reduce the number of seizures in patients with epilepsy.¹ It also shows promise for use in treating other chronic illnesses, including diabetes, Alzheimer’s, Parkinson’s, and cancer.²Given its potential health benefits, you may be wondering: is keto the best diet for hypothyroidism? Here’s what I recommend as far as keto and hypothyroidism go.

Keto and Hypothyroidism

The ketogenic diet is a low-carb, high-fat diet. It triggers the body’s natural metabolic process known as “ketosis.” Consuming minimal amounts of carbohydrates deprives your body of it’s natural fuel source, glucose, forcing it to use stored fat as fuel instead. As stored fat is broken down, your liver produces “ketones,” a type of fatty acid, and sends them into your bloodstream where your muscles and other tissues use them as fuel. Ketosis normally occurs in a fasting state, however it can also occur in the absence of glucose and in the presence of medium-chain triglycerides (MCTs), such as those found in coconut.

The keto diet reduces inflammation and modulates the immune response, particularly when it comes to your thyroid. You’ve likely heard me discuss how carbohydrates and sugars are highly inflammatory foods. For that reason, the best diet for hypothyroidism works to eliminate foods that feed inflammation.

What is Hypothyroidism?

Hypothyroidism, or having an underactive thyroid, is when your thyroid gland does not produce enough thyroid hormone. Thyroid hormones affect nearly every part of your body, including your metabolism, brain, heart, muscles, hair, and skin. Without enough thyroid hormone, all of your bodily processes slow down to a sluggish crawl. Research shows that women and those with autoimmune diseases are more likely to develop hypothyroidism.³

The Role Your Adrenal Glands Play

Chronic stress can also provoke hypothyroidism. Your adrenals produce stress hormones, such as cortisol. When you experience stress, a cascade of stress hormones signals your body to slow down all processes that are unnecessary for overcoming the stressor in front of you, including thyroid hormone production.

In our modern society, many of us experience one stressor after another with no time in between to physically recover. Chronic stress overworks your adrenals, which are unable to keep up with the constant demand for more and more stress hormones, inevitably leaving you in a state of adrenal fatigue. This flooding and eventual plummeting of stress hormones cause your thyroid activity to come to a screeching halt.

Adrenal Fatigue and Ketosis

While achieving ketosis has been attributed to rapid weight loss and enhanced energy and brain function, keto and hypothyroidism combined can be a major strain on the adrenals. Reduced carb intake leads to a decrease in thyroid hormone levels and an increase in cortisol—which decreases thyroid function further and means more work for your adrenals.⁴ If you are already seeing signs of adrenal fatigue, you do not want to stress them even more by going into ketosis.

This vicious cycle that happens between keto and hypothyroidism is why you should proceed with caution when choosing the best diet for hypothyroidism, particularly if adrenal fatigue is one of the primary triggers of your hypothyroidism. For this reason, I would recommend avoiding going into ketosis until you have addressed your stress levels.

Signs of Adrenal Fatigue

When you engage in stressful activities, your body enters into the fight-or-flight mode, where it believes that you need a surge of energy in order to survive. Cortisol’s main function is to provide you with that burst of energy. So when you are stressed, cortisol increases your blood sugar, suppresses your immune system to save energy, and begins breaking down your storage of protein and carbohydrates. Over time, high levels of cortisol can lead to insulin resistance, weaken your immune system, and eventually cause muscle wasting if not properly addressed. Other signs of adrenal fatigue include:

Unexplained weight loss or weight gain
Body aches and muscle pain
Fatigue (difficulty getting out of bed in the morning)
Low blood pressure
Salt and sugar cravings
Shakiness or lightheadedness after skipping a meal
Dizziness upon standing
Feeling tired and/or wired
Sleep disturbance
Low libido
Infertility
Thyroid imbalances
Hair loss
Blurred vision
Severe allergies

Avoid Keto Until Stress is Under Control

As I mentioned above, reducing your carb intake on a keto diet has the potential to increase your cortisol levels. When your adrenals are working in overdrive to produce enough cortisol, your immune system is weakened, which can lead to any of the signs of adrenal fatigue listed above and even autoimmunity.

Before considering a ketogenic diet, make sure your stress is under control to avoid further hormone imbalance.

Essential Nutrients for Thyroid Function

No matter which you decide is the best diet for hypothyroidism, it’s important to include these important chemicals and nutrients for keto and hypothyroidism:

Iodine

Iodine is one of the two building blocks for thyroid hormones. Your thyroid converts tyrosine (the other building block) into thyroglobulin and attaches between one and four iodine atoms to create T1, T2, T3, and T4 respectively. Without enough iodine, your thyroid simply can’t produce its hormones.

Selenium

The enzyme that converts T4 to T3 is a selenium-dependent enzyme, so without enough selenium, your thyroid hormones are stuck in their inactive state, causing hypothyroidism symptoms.

Zinc

Like selenium, zinc plays a role in the enzyme needed to convert T4 to T3. Zinc is also necessary to trigger your hypothalamus’ thyroid hormone receptors, meaning that without enough zinc, your hypothalamus can’t accurately gauge thyroid hormone levels to increase production when levels are low. Because of these two factors, studies have linked zinc deficiency with decreased thyroid production and hypothyroidism.

Iron

Iron contributes to two key steps to thyroid hormone production. First, the enzyme that converts iodide to iodine (so that it can combine with tyrosine to become thyroid hormones) is dependent on iron. Second, like selenium and zinc, iron is required to convert T4 to T3.

How to Determine if Keto is the Best Diet for Hypothyroidism

Everybody is different, so it’s important to listen to your body and know what you do or do not tolerate when choosing the best diet for hypothyroidism. You may do perfectly fine on a keto diet, or you might find your body doesn’t respond well to the combination of keto and hypothyroidism. Either way, if you determine that keto is the best diet for hypothyroidism, be sure to consult your doctor first and monitor your thyroid levels closely during this time.

Because most thyroid conditions are triggered by autoimmunity, it’s just as important to determine if you should try a keto diet if you have an autoimmune disease. Whether you choose a keto, AIP, Paleo, elimination, or any other diet out there, by focusing on nourishing your body and giving it the nutrients it needs, you’ll be on your way to achieving optimal health.

Helpful Supplements for Adrenal-Thyroid Health

The best way to support your adrenals and accompanying thyroid problems long-term is to manage your stress. Realistically speaking, there will always be stress in your life, but learning the tools and routines to leave a stressful situation behind after it’s over, instead of carrying it around with you, will reduce the physical effects of chronic stress. For additional support for adrenal-thyroid health, I recommend:

Adaptogenic herbs help the body adapt and cope with stress. My go-to supplement to support the adrenal gland contains Rhodiola rosea, Panax ginseng, and a number of other herbal extracts. Adrenal Support promotes a healthy stress response.
All B vitamins are critical for the chemical processes within the adrenal glands, which makes my multivitamin ideal for adrenal support. It contains all 8 B vitamins in their pre-methylated forms.
For added adrenal support, you can also take Omega-3 fatty acids, vitamin C, and magnesium.

If you are curious about your own adrenal health or would like further assistance in combating your adrenal fatigue or choosing the best diet for hypothyroidism, I highly recommend seeking a Functional Medicine practitioner in your area.