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Intermittent Fasting and Hypothyroidism: Is it Right for You?

Have you ever wondered if intermittent fasting and hypothyroidism are compatible with each other? As someone with Hashimoto’s Thyroiditis, the most common cause of hypothyroidism, it’s a question I often ask myself.  

I have struggled with maintaining a weight that I feel good about most of my life, and having hypothyroidism has only made it more difficult. Since you’re reading this, I’m assuming you or someone you love is in the same boat. 

Let’s dive into this together and explore the benefits and limitations of intermittent fasting (IF) and hypothyroidism. 

*Items marked with an asterisk are affiliate products. If you purchase through this link, I will earn a small commission at no extra charge to you. 

What is Hypothyroidism? 

Symptoms of Hypothyroidism

Individuals with an under-active thyroid gland, also known as hypothyroidism, do not make enough thyroid hormones. The two thyroid hormones (T3 and T4) control growth, metabolism, and body development, and take part in the production of other hormones.

When our bodies don’t make enough T3 and T4 we are more likely to become obese because of a slower metabolism. This makes it easy to gain weight and very difficult to lose it. 

In serious cases of hypothyroidism the metabolic rate can be lowered by as much as 50%, making it nearly impossible to lose weight with a generally healthy diet and an appropriate level of exercise alone.

I believe this is why so many people with Hashimoto’s look to intermittent fasting as a possible solution to this weight gain conundrum so many of us find ourselves in?

Hashimoto’s and Intermittent Fasting

Hashimoto’s thyroiditis (HT) is the most frequently diagnosed autoimmune disorder and the most common cause of hypothyroidism. HT is characterized by symptoms such as chronic fatigue and irritability, dry skin, hair loss, nervousness, and mood disorders.

Many individuals with HT experience an impaired quality of life due to the chronic fatigue and mental health struggles that are common in individuals with HT. 

In a recent post, I described the mental wellness struggles that I have experienced with HT. We will dive into that more a little later, as I have found several natural solutions that have worked wonders for me in the area of diminished mental wellbeing. 

Best Diet for Hypothyroidism

Little evidence exists to support the absolute best diet for individuals with hypothyroidism, or even hashimoto’s. However, while medical management with thyroid hormone replacement is the gold standard for treating hypothyroidism, nutrition plays a key role in thyroid hormone synthesis. 

Diet alone has not been shown to necessarily improve antibody markers or thyroid function significantly, however diet has been shown to improve quality of life through symptom management. Research always points me back to an anti-inflammatory diet, such as the Mediterranean Diet. 

Other popular nutritional approaches for the management of hypothyroidism symptoms, especially in hashimoto’s thyroiditis include following a gluten-free diet, the AutoImmune Protocol (AIP), or a paleo style diet.

What is Intermittent Fasting?

Intermittent fasting consists of alternating periods of unrestricted food consumption and fasting or abstinence from caloric consumption. IF is different from calorie restricted diets, in that calorie and macro counting are not necessary. Rather, dietary intake in general is limited to a shorter period of time, such as a 16:8 or 18:6 regimen. 

In a 16:8 IF plan, an individual would fast for 16 hours and eat during an 8 hour period of time. The same goes for the 18:6 intermittent fasting regimen, fasting for 18 hours and consuming food during the 6 hour eating window. A popular regimen among individuals that practice IF is maintaining an eating window from 12pm – 8pm daily and fasting the remaining 16 hours. 

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Benefits of Intermittent Fasting and Hypothyroidism

Lists 5 Benefits of Intermittent Fasting
5 benefits of intermittent fasting

It’s important to consider what your specific goals are with regards to intermittent fasting and hypothyroidism. Just as there is little evidence to support improvement in thyroid function with diet alone, the same is true for following an intermittent fasting regimen.  

If your goals are to improve your hypothyroid symptoms on the other hand;  weight gain, fatigue, inflammation, and mental health struggles, I believe IF may be an option for you to at least try and see if it’s a good fit for you. 

Time restricted eating patterns can improve various factors such as insulin sensitivity, systolic blood pressure, HbA1c, fat mass and triglycerides. Below I have outlined additional benefits, beyond weight loss, one might expect from IF. Keep in mind that the benefits observed may vary depending on each individual person. 

Anti-inflammatory Benefits

There are several mechanisms by which IF is shown to provide long term benefits, such as reducing systemic inflammation. It is thought that by reducing overall caloric intake and therefore reducing oxidative stress (ie. systemic inflammation) one can reduce the risk of developing long term conditions such as metabolic syndrome, non-alcoholic fatty liver disease and other neurodegenerative diseases. 

Weight loss

Intermittent fasting for weight loss is a controversial topic among Registered Dietitians and medical practitioners as a whole. There is not a lot of research to support IF as an effective weight loss tool, however there is a growing body of evidence that shows many benefits to IF, including weight loss. 

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While calorie restriction is not necessarily the goal with time restricted eating, these regimens have been shown to lead to a 20% unintentional calorie reduction. One of the most popular theories behind weight loss and IF is that IF leads to a reduction of total calorie intake, creating a metabolic shift that results in greater fat metabolism and reduced fat storage. 

Recent studies have shown significant decreases in BMI and waist circumference in individuals practicing IF, independent of calorie restriction. 

Intermittent fasting and hypothyroidism may be a good match. IF doesn’t require a lot of planning, calorie counting or tedious tasks that may be overwhelming when you are already suffering from chronic fatigue, brain fog and other symptoms. 

Improved Insulin Resistance 

Increased fat storage, especially central adiposity (belly fat), is correlated with decreased insulin sensitivity. This may lead to the development of Type 2 Diabetes. IF may reduce stored body fat and therefore improve insulin resistance through calorie reduction and metabolic reprogramming. 

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Gut Health

Intermittent fasting is thought to aid in improving bacterial richness of the gut microbiome. This is especially true with regards to Lactobacilli, which has many positive effects such as decreasing the immune inflammatory response. This bacterial richness is also shown to lower leptin and increase adiponectin.

Leptin, a pro-inflammatory hormone, helps suppress food intake and increase energy expenditure. Adiponectin, an anti-inflammatory hormone, improves insulin sensitivity. 

Part of my personal Hashimoto’s journey included incorporating probiotics, prebiotics and adaptogenic herbs into my daily regimen. When I started these products in 2019, I was desperate for answers and I wanted my life back.

Within three months of starting this regimen, I was a new person; more energetic, sleeping through the night, more stress resilient and I could think more clearly. You can learn more about my *Fundamentals Regimen here and my *Mood+ supplement here. 

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Mental Health Benefits

Mental health challenges are common in individuals with hypothyroidism, especially in those suffering from Hashimoto’s Thyroiditis. Some studies show a correlation between central adiposity (belly fat) and depression, even further emphasizing the struggle that individuals with hypothyroidism face concerning weight gain, which is often centrally located on the body. 

Additionally, the decreased quality of life that hypothyroidism causes in some individuals may lead to mood related disorders, such as anxiety and depression. It’s not uncommon for hypothyroidism sufferers to become too fatigued to leave their house and engage in activities that they used to find pleasure in. 

Limitations of Intermittent Fasting and Hashimoto’s

As mentioned previously, there is a divide in the healthcare community over the legitimacy of intermittent fasting. You will find just as many proponents as you will find skeptics. As a registered dietitian myself, it’s hard to argue with the many long term benefits that have been observed in individuals that consistently practice IF. 

If you are new to IF, it would be wise to proceed in a cautious manner when you begin your IF journey. I believe that gradual changes allow our bodies to adjust to these changes, rather than shocking them into submission. 

To avoid conditions such as adrenal fatigue and hypoglycemia (low blood sugar), I recommend gradually extending your fasting hours over a period of time. For example, you may decide to start out with a 12 hour fasting window and 12 hour eating window. After a few days or a week later you can advance to a 14 hour fast with a 10 hour eating window, and so forth. 

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Tips for Intermittent Fasting

Registered Dietitian, Su-Nui Escobar of Menopause Better, shares tips to avoid feeling hungry during fasting in this blog post. She states “sugary and high-carbohydrate foods cause insulin spikes, making you hungry. On the other hand, a diet rich in lean protein, healthy fats, vegetables, fruits, and complex carbohydrates can help you feel satisfied for longer periods because it will have a beneficial impact on hunger hormones”.

Additionally, there are supplements that can help you be successful on an IF plan, especially for weight loss. This *quadbiotic helps reduce bloating, reduce appetite and cravings, improve sleep, and reduce belly fat.  

Conclusion

I cannot tell you if intermittent fasting is the right choice for you. Just like any other method you try to help you lose weight or improve symptoms, it isn’t a guaranteed fix. I believe it’s worth a try if you have tried other methods to lose weight and have been unsuccessful or if you have unmanageable symptoms that are causing a decreased quality of life.

Although medical professionals may have to agree to disagree on this topic, some individuals do experience undeniable results. Only you can decide what works for you. 

The purpose of this information is to inform and empower the reader to make positive lifestyle changes. The intent is not to replace medical advice or instructions given by your doctor or healthcare provider.

References

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Morales-Suarez-Varela M, Collado Sánchez E, Peraita-Costa I, Llopis-Morales A, Soriano JM. Intermittent Fasting and the Possible Benefits in Obesity, Diabetes, and Multiple Sclerosis: A Systematic Review of Randomized Clinical Trials. Nutrients. 2021 Sep 13;13(9):3179. 

Song RH, Wang B, Yao QM, Li Q, Jia X, Zhang JA. The Impact of Obesity on Thyroid Autoimmunity and Dysfunction: A Systematic Review and Meta-Analysis. Front Immunol. 2019 Oct 1;10:2349. 

Wojtas N, Wadolowska L, Bandurska-Stankiewicz E. Evaluation of Qualitative Dietary Protocol (Diet4Hashi) Application in Dietary Counseling in Hashimoto Thyroiditis: Study Protocol of a Randomized Controlled Trial. Int J Environ Res Public Health. 2019 Dec 2;16(23):4841.

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