Is keto diet safe for your thyroid?

Popularity of keto diet is rising. There are of course lots of benefits of keto diet but in my opinion, keto may not be that safe for your thyroid in long term, especially if you struggle with underactive thyroid. You may be confused why sometimes keto is recommended to treat Hashimoto’s. Mostly it’s because it can help to manage inflammation. However, it’s not always true because if you don’t do keto in an appropriate way, you can actually increase inflammation. Remaining in ketosis for too long without enough alkalising food can lead to increased acidity which leads to inflammation. Anyway, let me explain why there are better diets to support thyroid than keto.

Ketosis is a ‘stress’ for the body

Studies showed that cortisol levels increase on ketogenic diet. This could happen because of increased water loss including increased excretion of sodium. Similar as during intermittent fasting or fasting in general. If sodium levels in the body drop too low, adrenals glands will release certain hormones to regulate it, including cortisol. Increased stress overworks your adrenals and that may lead to impaired hormone production including thyroid hormones. That can cause hormonal imbalance and bunch of various symptoms. In our modern society, many of us experience one stressor after another with no time in between to physically recover and adjust. Without addressing your stress levels, keto diet may only add fuel to the fire.

Low carbohydrate diet can inhibit thyroid hormone production

The thyroid needs glucose to produce its T4 hormones and the convert inactive T4 to active T3 form. Significant reduction in carbohydrates, especially in combination with strenuous exercises can increase cortisol. As results reverse T3 production can increase which inactivates T3 and converts T3 back to inactive form T4. I’ve heard that some people were saying you shouldn’t worry about keto and thyroid because the studies showed only decrease in T3 levels with no significant impact on T4 production. It doesn’t make sense to me as T4 has some function to perform as well but at the end of the day, active T3 is the one that we need the most so it’s definitely something to worry about if your T3 levels drop. No matter if it’s because of low conversion of T4 to T3 or increased reverse t3 activity.

Symptoms of low T3 hormones

With decreased T3 levels you may experience various hypothyroidism symptoms

  • Slow metabolism and weight gain
  • Constipation and bloating
  • Cold hands and feets
  • Low mood and anxiety
  • Hair loss and dry skin
  • Sleeping difficulties

What’s interesting, low T3 levels or underactive thyroid can increase your risk of SIBO and other gut issues.

Keto diet, liver and T4 to T3 conversion

Liver is responsible for converting T4 o T3. Keto diet can put additional load for your liver. Your body can adapt to burning ketons for energy but it’s not the easiest and quickest available energy source as glucose is. For example, if glucose is lacking in our system liver needs to make glucose from fatty acids through glucogenesis process and this is of course extra work for our liver. Eating high protein diet (which is also quite common for keto diet) generates more toxins that are by-products of protein digestion. Again, it means more work for your liver to process it and clear it.

What is the best diet for thyroid?

In general, I’m not supporter of any extreme diet in long term. If you need to address certain condition then some dietary restrictions can be applied but overall my golden rule is everything in moderation with emphasis of good quality, nutritious food. Keto has its benefits but may not be that safe for thyroid. Especially for underactive thyroid. Paleo diet with certain adjustments, sounds a more reasonable choice in my opinion. For thyroid, definitely you need to ensure appropriate intake of key nutrients like iodine, tyrosine, selenium, iron, zinc, vitamin E, A, D and B vitamins. Also, adequate vitamin C intake is important because of the adrenals that are closely connected with thyroid. Gluten free, dairy free diet and addressing any food intolerances is also recommended. Make sure you include enough fibre and probiotics as well as maintaining healthy gut is one of the basic things you can do to improve your thyroid health.

If you are interested more about thyroid diet and what foods should be avoided with hypothyroidism click here

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