What Intermittent Fasting Does To Your Thyroid


People everywhere are using an intermittent fasting diet to massively boost their body’s ability to function and heal.

Given that an intermittent fasting diet has been shown to help alleviate a number of conditions, I have people constantly asking me if an intermittent fasting diet is right for them. One that I get a lot is people with hypothyroidism. While opinion varies in the field, I think an intermittent fasting diet for hypothyroid conditions can be super beneficial if you do it right.

Of course, with anything pertaining to a health condition, you have to take into account unique factors per individual and per condition when designing a health plan. The following is the intermittent fasting plan I would recommend for someone dealing with hypothyroidism and factors you should consider when following one.


Hypothyroidism is generally characterized by inadequate thyroid activity in the body. From a traditional medical standpoint, it is often referred to as the thyroid not producing enough hormones. This is a limited view however as thyroid hormones can be imbalanced due to a number of reasons that have little to do with the thyroid gland itself.

People who are struggling with a hypothyroid typically experience low energy, weight gain, mood imbalances, foggy thinking, and overall lowered vitality. Those that have been diagnosed with hypothyroidism will usually be put on thyroid hormone replacement without addressing any root cause.

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HPT Axis

The whole thyroid hormone regulation process is actually a delicate dance between the brain (hypothalamus and pituitary), thyroid, liver, and even the gut in some ways. Together, there are a number of signaling and conversion processes that take place. These can be thrown off in a number of different ways that have almost nothing to do with the actual thyroid gland.

The hypothalamus and pituitary in the brain constantly monitor the body and regulate what signals get sent to the thyroid. Various factors can influence this process as we will discuss later in this article.

When you are looking to design a healthy lifestyle for someone who has been diagnosed with hypothyroidism, the entire process of thyroid hormone production needs to be considered, not just the gland itself.

Intermittent Fasting Diet

Intermittent fasting (IF) describes a pattern of eating that cycles between periods of fasting and normal eating.

The most common methods include fasting on alternate days, daily 16-hour fasts or fasting for 24 hours, two days a week. For the purpose of this article, the term intermittent fasting will be used to describe all regimens.

Unlike most diets, intermittent fasting does not involve tracking calories or macronutrients. In fact, there are no requirements about what foods to eat or avoid, making it more of a lifestyle than a diet.

Many people use intermittent fasting to lose weight as it is a simple, convenient and effective way to eat less and reduce body fat.

It may also help reduce the risk of heart disease and diabetes, preserve muscle mass and improve psychological well-being .

What’s more, this dietary pattern can help save time in the kitchen as you have fewer meals to plan, prepare and cook.

Intermittent Fasting and Inflammation

For one, reducing inflammation boosts just about every process in the body. Chronic inflammation is damaging to the cells and especially to the mitochondria. Mitochondria produce all of the energy for the body and dictate how well your body is able to function.

Chronic inflammation also distracts the immune system which can contribute to autoimmunity, a common cause of hypothyroid.

Additionally, this style of eating encourages a healthy metabolism by burning off excess fat and stabilizing blood sugar levels. Without going into too much detail, an intermittent fasting diet simply enables the body to function at a much more efficient level and this may allow for a more balance production of thyroid hormones.

Intermittent Fasting Diet and Thyroid

There is an idea in the functional medicine community that following an IF diet is bad for thyroid health. This idea is not supported by research. There is some evidence that following a IF diet may lower T3 levels however. This does not necessarily qualify as hypothyroid and may actually be beneficial.

In fact, this lowered T3 is seen with calorie restriction and protein restriction as well. Evidence seems to point to lowered T3 as a physiological adaptation in the body that allows for a deeper state of ketosis and preserved muscle mass (this is a good thing).

This is given that TSH and T4 levels remain normal.

This is where it is really important to monitor how you are feeling on a day-to-day basis and determine how you are responding to a ketogenic diet. T3 levels may be slightly depressed, however if you are feeling very good then it is not really a concern.

Like I said this drop in T3 allows for deeper ketosis and preserved muscle mass. Additionally, and interestingly enough, low T3 levels are actually associated with a longer lifespan in research.


Lowered Inflammation

One of the huge benefits for hypothyroidism with a ketogenic diet is lowered inflammation. Lowering inflammation can assist with hypothyroid by improving T4-T3 conversion and reducing autoimmune activity. Especially in cases of autoimmune thyroiditis, such as Hashimoto’s, this effect can be extremely beneficial.

Many people with hypothyroidism have found that they feel great on a ketogenic diet. There are some considerations I would suggest reviewing before starting one yourself. They mostly have to do with supporting healthy thyroid hormone conversion.

READ ALSO: How To Lose 50 Pounds Or More Using An Intermittent Fasting Diet

Blood Sugar Imbalance

Rapidly fluctuating blood sugar contributes to the formation of inflammatory proteins called advanced glycolytic enzymes (AGEs). These AGEs have a high affinity for thyroid tissues and may inhibit thyroid hormone production.

Luckily, following a ketogenic diet will automatically drop and stabilize insulin and blood sugar. That is as long as you control stress levels and avoid common food sensitivities.

Stress and reactive foods can cause cortisol responses that stimulate the release of glucose, causing blood sugar spikes even when not consuming a lot of sugars. Controlling these factors will drastically improve your chances of success.

Low Calories

Not consuming enough calories for a prolonged period of time can result in the body shifting to a state of conservation. It has been shown that calorie restriction is often associated with lower T3 levels. As I mentioned earlier, this is most likely a conservatory mechanism of the body for times of scarcity. This can also lead to many hypothyroid symptoms that are mistakingly attributed to a ketogenic diet.

Ensuring you are consuming enough calories is another factor to consider when designing your ketogenic diet plan.


Many people who convert to a ketogenic diet have drastically changed the types of foods they eat in a short amount of time. It is important to ensure you are still receiving all necessary conversion factors in your diet for healthy thyroid hormone levels.

Iodine, tyrosine, Vitamin A, Selenium, Zinc, B Vitamins, Vitamin C, and Vitamin E are all important for the production of thyroid hormones.

Consuming the kinds of foods outlined in a healing diet will ensure a diverse array of nutrients. This includes wild-caught fish, pasture-raised meats and dairy, and plenty of nutrient-dense vegetables. Strategic supplementation can also be extremely helpful as it is a much more reliable way to reach therapeutic dosing of these nutrients.

Chronic Stress

Chronic stress cranks up the production of something called rT3, or reverse T3. What rT3 does is essentially blocks T3 from exerting its effects in the body. While by traditional standards this would not be considered pathological hypothyroidism, the symptoms would be very similar.

The release of cortisol due to chronic stress also directly inhibits the enzyme (5’-deiodinase) which converts inactive T4 into active T3. This can lead to low T3 levels.

Making sure that you are taking steps to control your stress during this time is critical for maximizing therapeutic benefits.

Types of Fats

While it is pretty common knowledge at this point that vegetable oils should be avoided at all costs, I figured it should still be mentioned here. Processed vegetable oils that are high in polyunsaturated fatty acids may have a negative impact on thyroid hormone signaling.

Conversely, healthy fats like those found in wild caught fish may actually improve thyroid hormone signaling.

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Best Ketogenic Strategies

If you are going to implement a ketogenic diet to assist in healing hypothyroidism, there are a number of things you should take into account before starting. I have found that a cyclic ketogenic diet works best for individuals who are susceptable to hypothyroidism. With these individuals, my health coaches and I try to find the best periods to cycle in healthier carbs to keep the thyroid stoked while getting the anti-inflammatory benefits of keto.

In addition, individuals with hypothyroidism will have trouble producing enough stomach acid, bile and pancreatic enzymes for proper digestion. We support them with Betaine HCL, ox bile and digestive enzymes. We also try to focus on small and medium chain fats and get them doing things like MCT oil, which dosn’t depend upon bile for digestion and turns into ketones quickly in the body.

Carb Cycling

I have found that most people do best when following a cyclic style of ketogenic diet. This means that while most of the time they will be following a very low-carb meal plan, there are periodic times where carb intake is increased to restore and replenish glycogen within the body.

You can do this in several variations, however I usually recommend going 6 days in ketosis with 1 day every week that is higher in carbs. On these days, you can utilize slow-digesting carb sources like sweet potatoes to temporarily cycle out of ketosis.

HCl & Gallbladder

Something that I have noticed is that hypothyroid individuals often have very poor digestion. This can manifest in two ways; low stomach acid and poor gallbladder function. Both of these processes should be supported in order to optimize therapeutic benefits.

Supplementing with a comprehensive digestive aid can be super helpful for assisting the digestion of proteins and fats to relieve stress on the digestive tract.


Another great way to support ketosis and relieve stress on the gallbladder is to supplement with MCT oil.

This is essentially oil that is refined from coconut oil that provides a very readily absorbed source of ketones so your digestive tract and liver do not have to do as much work to convert them.

This will be especially important in cases of poor gallbladder function and near critical if the gallbladder has been previously removed. As mentioned previously, hypothyroid individuals typically do have issues with gallbladder function.

What Do People Who Heal Their Thyroid With A Keto Diet Know That You Don’t?

Although a bit controversial for a while, using a ketogenic diet for hypothyroid conditions can actually be very beneficial. Follow the strategies outlined above to ensure you maximize your therapeutic effects.

What are THEY doing that you aren’t?

I’m sorry to say, it’s not the latest exercise craze, dietary supplements, magic pill, or extract that’s helping others lose weight.

It’s a sustainable program that is focused on your unique metabolism, hormones, and lifestyle. A program with YOU in mind.

When I launched the 3-Week Intermittent Fasting Diet 1 year ago, I never thought over 3,000 people would have downloaded and used this plan. Much less have over 100 people lose over 20 pounds in 21 days.

The results keep coming in and I’m STILL shocked to see some of the transformations, but the messages NEVER get old.

If you’d like to become the next success story, then watch the free presentation and read the success stories, then share yours in 3ish weeks inside our private support group on Facebook, here’s some of the messages:


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