For such a small gland, the thyroid has a huge impact on your health and wellbeing. 

Let’s look at thyroid health, and whether or not fasting can be a benefit. 

What is the thyroid and why does it matter?

Your thyroid is a butterfly-shaped gland that sits in your neck. It makes and releases hormones. 

The two main hormones produced by the thyroid are triiodothyronine (T3) and thyroxine (T4).

The thyroid controls your metabolism, energy levels, body temperature, and even has an impact on your mood. 

When it’s functioning as it should, you likely don’t even think about your thyroid.

But when this little gland is out of balance, you’ll definitely be aware of it in a big way. 

There are several different thyroid conditions that can occur, but the two most common ones that we see (especially when it comes to weight loss/gain) is Hyperthyroidism and Hypothyroidism. 

Hyperthyroidism 

This is when the thyroid is overactive and produces too much thyroid hormone, causing your metabolism to be sped up. 

Causes of hyperthyroidism vary, including autoimmune disease, nodules on the thyroid, or viral infections. 

Symptoms can include:

• Weight loss despite eating well

• Anxiety

• Rapid heart rate

• Shakiness

• Issues with sleep

• Increased sweating 

• Goiter (enlarged thyroid)

• Hair loss or brittle hair 

Hypothyroidism 

On the other end of the spectrum, hypothyroidism is when the thyroid is underactive and not producing enough thyroid hormone. 

This is usually the one we see in weight loss discussions, because one of the major symptoms is weight gain and/or inability to lose weight, even when you’re doing all the right things. 

Some other symptoms of hypothyroidisms include:

• Fatigue

• Sensitivity to cold

• Dry skin

• Thinning hair 

• Hoarse voice 

• Depression

• Muscle weakness 

Some of the causes of an underactive thyroid include autoimmune disease, iodine deficiency, and thyroid surgery. 

And while menopause itself does not cause hypothyroidism, the two are often linked because the risk of hypothyroidism increases with age. 

Does fasting benefit thyroid health?

Fasting is a powerful tool for weight loss, health, and longevity. 

But if you’re fasting, or planning on fasting, it’s good to know how it might affect your thyroid. 

Especially if you’re already experiencing thyroid issues. 

And the answer is not so straightforward. 

While there are studies and research that suggests that calorie restriction is not good for the thyroid, you have to remember that fasting does not mean calorie restriction. 

Calorie restriction is eating some, which means you have an insulin response. 

Fasting means you’re eating nothing, and having no insulin response. So it’s not the same thing. 

There is anecdotal evidence that fasting benefits the thyroid. 

Many people have reported drastic improvements in thyroid function with fasting. 

And leading fasting expert, Dr. Jason Fung, says that the thyroid doesn’t really get affected by fasting. 

He notes that the main hormonal changes of fasting are on insulin, and not so much thyroid hormones. 

Fasting also reduces inflammation, which is good for the thyroid. 

So can fasting benefit the thyroid? Probably. Is it bad for the thyroid? There’s no real, scientific evidence of that. 

Tips for thyroid health while fasting 

Like everything else, balance is key. 

• Don’t overdo Extended Fasting - Break these longer fasts up with periods of Intermittent Fasting

• Vary your fasting schedule 

• When you feast, make sure you aim for nutrition and always eat till satisfied 

• Stay hydrated and take your electrolytes

• If you’re currently on thyroid medication, you need to know if it requires food in the gut. If so, you can do Intermittent Fasting instead of Extended and time your medication with meals

Foods that support healthy thyroid function 

When not fasting, focus on whole foods, healthy fats, and proteins. 

Avoid seed oils, sugars, and processed foods. 

Don’t restrict calories. When you fast, you fast. But when you feast, you need to nourish yourself. 

Note: If you have thyroid issues or you’re experiencing symptoms of overactive or underactive thyroid, it’s important that you check in with your doctor before you practice fasting. 

Bottom line

A healthy thyroid is vital to your wellbeing. 

Fasting can benefit the thyroid, but as with everything else, you need to do it in a safe and balanced way.