Keto And Hypothyroidism: Is There A Link?

The ketogenic diet is a low-carb, high-fat diet that triggers the body's natural metabolic process, ketosis. This process is known to reduce inflammation and modulate immune response, particularly in the thyroid. However, there are concerns about the impact of keto on thyroid function and the potential development of hypothyroidism.

Hypothyroidism is when the thyroid gland does not produce enough thyroid hormone, resulting in a slowdown of bodily processes. The keto diet's restriction of carbohydrates can affect the body's ability to convert the inactive thyroid hormone T4 into the active and functional form T3. This is because carbs are needed for the deiodination process, which occurs in the liver, kidneys, brain, and gut.

Research has shown that a keto diet can increase stress hormones like cortisol, which can further decrease thyroid function. Additionally, the body's prolonged state of ketosis on a keto diet may lead to increased acidity and inflammation, which can be detrimental for those with hypothyroidism.

While some studies suggest that keto may decrease thyroid function, others indicate that it may improve thyroid hormone sensitivity, allowing the body to function normally with lower T3 levels. The impact of keto on thyroid function is still a subject of ongoing research, and there is no conclusive evidence that it directly causes hypothyroidism.

Carbs are needed to make thyroid hormones work

The thyroid makes two types of thyroid hormone: the inactive T4 (thyroxine) and the active hormone, T3 (triiodothyronine). Most of the thyroid hormone secreted is T4, which needs to be converted into T3, the active form. This conversion requires a specific enzyme called 5'-deiodinase. Low-carb diets can reduce the activity of this enzyme, resulting in low levels of T3 production.

Research shows that:

• Carbs are important for deiodination and they directly impact the levels of T3 in your body.
• The amount of carbs in your diet directly impacts how much of T4 gets converted to T3, the functional form of thyroid hormone.

Thyroid hormones influence your metabolism or how your body uses energy. When your thyroid hormone levels are too high, your metabolism speeds up. Low thyroid hormone levels, or hypothyroidism, cause your metabolism to slow down. The production of thyroid hormone depends on a constant energy source. Restricting carbohydrate intake can decrease your thyroid’s ability to produce and secrete thyroid hormone. Ultimately, this can leave you feeling more tired or sluggish.

Carbohydrates trigger the release of insulin, a hormone that regulates blood sugar levels by moving the sugar into your cells. Once inside, your cells use sugar for energy. If your body does not get enough carbs over time, this can impact how your cells respond to insulin, known as insulin sensitivity. A decrease in insulin sensitivity means your cells can’t move sugar into your cells, thus impacting how they function. In the case of your thyroid, the outcome would be a lack of thyroid hormone production.

Low-carb diets mimic a fasting state, causing your body to rely on other macronutrients for energy. Gluconeogenesis is the process of making sugar from a non-carbohydrate source. Gluconeogenesis increases slightly in those following a low-carb diet. But gluconeogenesis can’t make enough sugar to supply all your cells with a constant energy source. Evidence shows that during a state of fasting, your T3 levels decrease.

In summary, carbohydrates are an essential energy source for all your cells, including your thyroid cells. Not eating enough carbohydrates impacts thyroid hormone production, conversion, and regulation. Thus, low-carb diets may disrupt your thyroid function.

Keto puts you in fight or flight, which is bad for your thyroid

The keto diet is a low-carb, high-fat diet that triggers the body's natural metabolic process known as "ketosis". However, when we don't consume carbs, the body has to figure out how to make carbs to sustain blood sugar. This is where the fight or flight mode comes in.

The body relies heavily on stress hormones, cortisol, and adrenaline, to make carbs from protein and fat. Cortisol is responsible for increasing gluconeogenesis in the liver, a process that makes carbs from protein and fat. Adrenaline also supports gluconeogenesis.

Research shows that people with hypothyroidism tend to have higher levels of stress hormones. We don't want to make dietary changes that make those hormones even higher as can happen with the combination of keto and hypothyroidism!

So what happens when you have high stress hormones? Cortisol, a stress hormone, raises Thyroid Stimulating Hormone (TSH). A high TSH value corresponds with a sluggish thyroid, or hypothyroidism. Cortisol also slows the conversion of T4 to T3 by directly impacting deiodinase activity and increases reverse T3 – an inactive form of T3 that can no longer be used by the body.

A keto diet could put people with hypothyroidism at an even greater risk for high cortisol levels, which can then increase their risk for diabetes and heart disease.

Micronutrient deficiencies

Two specific micronutrients that are important to focus on are potassium and vitamin C. The body needs potassium for pretty much everything it does, including supporting the kidneys, heart, muscles, and nervous system. People with hypothyroidism tend to have low potassium levels, so it's crucial for them to include a variety of potassium-rich foods, like fruits and vegetables.

The best way to get enough potassium is to eat plenty of fruits and vegetables, especially root vegetables like potatoes, sweet potatoes, beets, and squashes, or fruits like bananas, apples, and mangoes. Eating plenty of fruits and vegetables will be challenging on a keto diet.

Vitamin C is a water-soluble vitamin that the body cannot produce on its own and must be obtained through diet. It is an antioxidant that reduces inflammation in the body and helps regenerate other antioxidants like vitamin E. Vitamin C is also involved in protein metabolism and helps make connective tissue and some neurotransmitters.

Vitamin C can also help with the better absorption of thyroid medication and improve thyroid function by reducing TSH and increasing blood levels of T3 and T4. Experts recommend that people with hypothyroidism aim for 200-400 mg of vitamin C per day, which is three times the recommended daily amount. Ensuring adequate vitamin C intake on a keto diet requires careful planning.

Supplements are not a simple solution to micronutrient deficiencies. As a registered dietitian, I recommend that my clients take a "food first" approach, aiming to get as many essential nutrients from natural sources as possible. The nutrients in food tend to work together in harmony and are usually in the most absorbable form for the body.

Supplements may be in a less absorbable form because it is cheaper to produce them that way. There is also no guarantee that a multivitamin will have everything you need. Most don't have enough potassium or vitamin C, for example.

For these reasons, I do not recommend trying to meet your potassium needs through supplementation. However, there are times when a supplement is warranted, and there is no one-size-fits-all approach to hypothyroidism. Every person's needs, preferences, and lifestyle are unique, so consider working with a knowledgeable registered dietitian to find the best eating plan for your health conditions and goals.

The keto diet is unsustainable

The keto diet is a low-carb, high-fat diet that triggers the body's natural metabolic process, "ketosis". While it has proven effective in reducing seizures in patients with epilepsy, it is not a sustainable diet for most people. Here are several reasons why:

Carb Intake

Carbohydrates are an important source of energy for the body, and reducing carb intake can have negative consequences. On the keto diet, carb intake is typically restricted to 50 grams or fewer per day. This means eliminating or significantly reducing nutrient-dense carbohydrate foods such as grains, lentils, fruits, and vegetables. As a result, people on the keto diet are at risk of vitamin and mineral deficiencies, including potassium and vitamin C. Potassium is essential for supporting the kidneys, heart, muscles, and nervous system, and most people already consume less than the recommended daily amount. Similarly, vitamin C is a water-soluble vitamin that acts as an antioxidant and helps with protein metabolism and the production of connective tissue and neurotransmitters.

Stress and Adrenal Fatigue

Adrenal fatigue is a common issue for people with hypothyroidism, and the keto diet can exacerbate this problem. When the body is deprived of carbohydrates, it relies on stress hormones such as cortisol and adrenaline to sustain blood sugar levels. Cortisol is responsible for increasing gluconeogenesis in the liver, the process of making carbs from protein and fat. People with hypothyroidism tend to have higher levels of stress hormones, and the keto diet can further increase cortisol levels, putting them at greater risk for diabetes and heart disease. Additionally, high cortisol levels can lead to insulin resistance, weaken the immune system, and cause muscle wasting over time.

Micronutrient Deficiencies

The keto diet's restriction of carbohydrate-rich foods can lead to deficiencies in essential micronutrients. In particular, the diet may lead to deficiencies in thiamin, folate, vitamins A, E, and B6, calcium, magnesium, iron, and potassium. These deficiencies can cause various health issues, including constipation, heart palpitations, extreme fatigue, muscle twitches and cramps, apathy, and high blood pressure.

Unsustainability and Weight Gain

The keto diet is challenging to maintain and often leads to weight gain in the long run. It is highly restrictive, and over 50% of people fail to adhere to it correctly in medical studies. Even if followed correctly, the keto diet is not intended for long-term adherence and is not uniquely effective for weight loss. Studies show that after six months, the keto diet does not lead to significantly higher weight loss compared to other weight loss approaches. Once a normal diet is resumed, the weight lost is often regained, and sometimes even more weight is gained.

In conclusion, while the keto diet may be beneficial for specific medical conditions such as epilepsy, it is not a sustainable or healthy approach for most people, especially those with hypothyroidism. It can lead to nutrient deficiencies, increased stress and cortisol levels, and weight gain in the long term.

Hypothyroidism and Hashimoto's disease are complex and require a personalised approach

Hypothyroidism and Hashimotos disease are complex and require a personalised approach

The ketogenic diet is a low-carb, high-fat diet that has been used to treat epilepsy and is being explored for other conditions. The diet works by triggering ketosis, a metabolic state where the body burns fat for fuel instead of glucose.

Hashimoto's disease is an autoimmune disorder where the immune system attacks the thyroid gland, resulting in hypothyroidism. This can be caused by genetics, radiation exposure, and environmental factors. Symptoms include fatigue, hair loss, sleepiness, constipation, depression, low heart rate, and more.

The keto diet's restriction of carbohydrates can impact thyroid function as the hypothalamus and pituitary gland, which regulate thyroid hormones, require glucose to function. Carbohydrates are also needed for the conversion of T4 (inactive thyroid hormone) to T3 (active thyroid hormone).

Research suggests that a keto diet may:

• Reduce oxidative stress and increase energy
• Reduce inflammation, which is common in Hashimoto's
• Regulate blood sugar levels, which are often spiked in people with Hashimoto's

However, there are potential drawbacks to the keto diet for people with Hashimoto's:

• Irregular bowel movements
• Increased stress levels due to the body's reliance on stress hormones to produce glucose
• Micronutrient deficiencies, especially potassium and vitamin C, as these nutrients are abundant in carb-rich foods
• Exacerbation of Candida overgrowth, a potential co-occurring infection in people with Hashimoto's
• Liver health issues, as the liver works harder to detoxify the body on a high-fat diet

Additionally, the keto diet may not be sustainable long-term, and weight loss may not be maintained.

Therefore, while the keto diet may offer some benefits for people with Hashimoto's, it is not a one-size-fits-all solution. It is important to consult with a healthcare professional and monitor thyroid levels closely when considering a keto diet. Individual needs may vary, and a modified keto diet with a higher carbohydrate intake may be a better option for some.

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