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Intermittent Fasting and Thyroid Health

Published July 28 2014

I’ve had a few people ask me about the benefits of intermittent fasting.  There is almost no question that caloric restriction has positive health benefits in most people.  Although long term studies are lacking in humans, studies show that caloric restriction in other animals results in a decrease in chronic health conditions and an increase in lifespan.  Does this mean that people with thyroid and autoimmune thyroid conditions should consider intermittent fasting?

For those who aren’t familiar with intermittent fasting, this involves either taking a couple of days per week and minimizing the amount of calories on those days, or minimizing the amount of calories on a daily basis.  For example, one of the more popular diets is called the 5:2 intermittent fasting diet.  This involves eating a normal diet five days per week, and restricting calories on the other two days (500 calories or less if you’re a woman, and 600 calories or less if you’re a man).  Another method of intermittent fasting involves restricting calories on a daily basis.  For example, after you eat dinner you wouldn’t eat again for 16 to 18 hours.  So essentially you’d only be eating for six to eight hours per day, although you wouldn’t be restricting calories during this time frame.

There is also another type of fasting routine called “alternate-day fasting”, which involves eating normally for a 24 hour period, fasting for 24 hours, eating for 24 hours, fasting for the next 24 hours, etc.  Animal studies of alternate-day fasting find lower diabetes incidence, lower fasting glucose and insulin concentrations, lower total cholesterol and triglyceride levels, a lower heart rate, and lower blood pressure (1) [1].  However, more human studies need to be conducted.

Intermittent Fasting: A Diet Option or A Lifestyle Choice?

There are a few reasons why intermittent fasting is appealing to many people.  Of course the primary factor many people like about this diet is that it can successfully help many people to lose weight…and to keep it off for as long as they maintain this diet.  Another reason why many people like the idea of intermittent fasting is because they feel they have more flexibility with their diet.  In other words, some people lose weight following this diet even when eating unhealthy food.  I definitely don’t support this, as I never recommend any “diet” simply for the sole purpose of losing weight.  If someone wants to do intermittent fasting to assist with losing weight that’s fine, but for optimal health you want to eat a whole foods diet during this time, and minimize the refined foods.

Plus, just as is the case with other types of diets, intermittent fasting doesn’t work for everyone when it comes to losing weight.  While caloric restriction and regular exercise can help many people with weight loss, other factors might need to be addressed before someone can successfully lose weight.  First of all, if someone has an imbalance of the hormones estrogen and progesterone then this can make it very challenging to lose weight and needs to be addressed.  Insulin resistance is another factor that can cause problems with losing weight.

Can People With Thyroid Conditions Benefit From Intermittent Fasting?

I do think that some people with thyroid and autoimmune thyroid conditions can benefit from intermittent fasting.  However, there are a few categories of patients who specifically need to be cautious about this type of dietary routine:

1. People with hyperthyroidism and Graves’ Disease. Although there are some people with hyperthyroid conditions who have problems losing weight, most people with hyperthyroid conditions have difficulty gaining weight.  This was the case with me when I was diagnosed with Graves’ Disease, as I lost approximately 40 pounds and had a difficult time putting on weight.  So if someone has lost a lot of weight and can’t afford to lose any more weight, then in my opinion, intermittent fasting probably isn’t a good idea until the hyperthyroid condition has been corrected.

2. Those with hypoglycemia. In past articles and posts I’ve spoken about the importance of eating breakfast and then eating regularly throughout the day.  This is important for many people, but especially those with hypoglycemia.  As a result, if someone has hypoglycemia I would discourage them from doing intermittent fasting until this condition has been corrected.

3. Some patients with adrenal problems. Most of the patients I work with have adrenal problems.  However, there are different stages of compromised adrenals.  If someone has depressed cortisol levels and also has depressed DHEA levels then it probably is a good idea to not follow an intermittent fasting routine.

4. Women who are pregnant. Caloric restriction during pregnancy is contraindicated for women with a normal body mass index (2) [2].  But how about those who are pregnant and overweight?  This remains controversial, and due to the lack of human studies involving caloric restriction and pregnancy it probably would be best to play it safe and avoid any type of fasting routine during pregnancy.

My Personal Experience With Intermittent Fasting

Recently I decided to follow an intermittent fasting routine.  There are different ways of doing this, but I chose to stop eating around 7pm, and then I didn’t eat until somewhere between 11am to 1pm the next day.  Not eating after 7pm wasn’t too big of a challenge since I rarely eat late anyway, but I’ve always been a big advocate of eating breakfast, and so before following the intermittent fasting routine, on most days I would have a smoothie within one hour of waking up.

The first few days were a little bit challenging.  What made it even more challenging was that I’m more of a morning person, and so when I’m not consulting with patients or responding to emails I’m usually creating content for my articles, blog posts, or webinars.  But after a few days I began getting used to skipping my morning smoothie, and it wasn’t a problem waiting until 12 noon or 1pm to eat my first meal.  While I didn’t eat my first meal until around 12pm to 1pm on most days, I did drink plenty of water, and I usually would have some green tea around 10am.

Although I didn’t try out intermittent fasting in order to lose weight, I did shed a few pounds over the first month, but then my weight began to stabilize.  I’m no longer following this routine, as a couple of months ago I decided to follow a detoxification program, and during this time I began eating breakfast again.  Despite my “experiment”, I still feel that eating breakfast is important for most people, and so in the future I might try a different intermittent fasting routine which involves consuming breakfast and lunch, and either skipping dinner, or having a very light dinner around 5:30pm, and then not eating again until breakfast the next day.  To be honest, skipping dinner on a routine basis probably isn’t an option I’d consider since I enjoy eating dinner with my family, and I’m sure that for the same reason many other people reading this would also find skipping dinner daily to be more challenging than skipping breakfast.

Should You Give Intermittent Fasting A Try?

Although I’m sure there are some people reading this who have already tried intermittent fasting, and perhaps some who are currently following this type of diet routine, I know there are others who haven’t tried this and might be wondering if it’s something they should consider.  I do think that many people can benefit from intermittent fasting.  However, if someone has an autoimmune thyroid condition such as Graves’ Disease or Hashimoto’s Thyroiditis, then I’m not sure if this is the best diet for them.  This is especially true for those with hyperthyroidism or Graves’ Disease who are rapidly losing a lot of weight.

As for those people with hypothyroidism and Hashimoto’s Thyroiditis, intermittent fasting might offer some great benefits, especially for those who are dealing with conditions such as insulin resistance and obesity.  However, there are some healthcare professionals who don’t think that people with hypothyroid conditions should follow an intermittent fasting routine.  Unfortunately there is a lack of studies on caloric restriction and hypothyroidism.  One thing to keep in mind is that some people with Hashimoto’s Thyroiditis have normal thyroid hormone levels, and so perhaps those with low or depressed thyroid hormone levels need to be more cautious with caloric restriction.

To be honest, this isn’t something I have tested on many of my patients, and so I can’t tell you from self experience how most people with thyroid and autoimmune thyroid conditions will respond to intermittent fasting.  But if I do try to incorporate this into my practice in the future I will definitely write an updated article on this.  Just remember that while intermittent fasting might help some people to lose a good amount of weight, this shouldn’t be the primary purpose of incorporating this routine.   The main reason to choose intermittent fasting is to help improve one’s overall health by restricting one’s caloric intake while at the same time continuing to eat a healthy diet.

In summary, caloric restriction can have some great benefits in decreasing chronic health conditions and increasing lifespan.  This is especially true in this day and age, when overeating is the norm.  As a result, some people with thyroid and autoimmune thyroid conditions might benefit from intermittent fasting.  However, certain categories of people should refrain from this type of diet routine, including most people with hyperthyroid conditions, as well as those with hypoglycemia.  And those people with adrenal fatigue, as well as those who are pregnant should also avoid intermittent fasting.  Although I personally have had a good experience with intermittent fasting, I have yet to routinely recommend it to some of my patients.