PART 1: THYROID – Keto & Fasting ‘BAD’ for Hormonal Imbalance?

Sixteen years ago, after having my third daughter,  I was diagnosed with Hypothyroid Disease (an underactive thyroid – which I would later learn was Hashimoto’s – an autoimmune thyroid disease).  That put me on a path to learn everything I could about the disease – both hypothyroid AND autoimmunity – and boy, is there a LOT to learn.

As I researched the thyroid gland and it’s physiology, I realized the connectedness the thyroid has to the adrenals, to stress and what’s known as the HPA Axis (Hypothalamic, Pituitary, Adrenal Axis).  There are hormonal axes stemming from the brain that involve the thyroid, pancreas and ovaries (sex hormones) as well.

As much as science and medicine want to compartmentalize every organ and condition, know this:

It’s all connected – just like everything in the ‘body-mind’ – Ultimately, it comes down to how the mind communicates with our autonomic nervous system  and how we perceive and respond to “stress” – or let’s just call it “life” (am I right?!)

So a few years ago as I continued to struggle with fatigue, brain fog and weight gain/weight loss resistance – which I attributed to the Hashimoto’s, I came across the Ketogenic diet. At the same time, I also started to hear more and more about Intermittent Fasting.

A few famous functional medicine doctors I highly respected had been teaching that Keto and fasting was not appropriate for thyroid disorders because it lowered thyroid hormone (T4>T3) conversion (T3 is the active thyroid hormone used by every cell in the body for metabolism).  Basically, the thyroid gland produces mostly T4 hormone (~93%). The liver and gut convert most of the T4 to the active T3 in an enzymatic process that uses glucose. So the thinking was: KETO = LOW CARB (LOW GLUCOSE) = NOT GOOD FOR THYROID CONVERSION, but that belief is short sighted.

Zooming out a bit, the feedback loops between the adrenals, gut, liver and pancreas need to be considered. When it comes to low thyroid function, know that the thyroid is responsible for glucose metabolism. It is THE MASTER GLAND for metabolism – including carbohydrate breakdown and utilization.

So when we’re HYPO (under-active thyroid), we naturally become less efficient at metabolizing carbs which increases our insulin resistance because the glucose (carbs) we eat has a hard time entering the cells.  The pancreas then pumps out more insulin because there’s more glucose in circulation. It’s looking for a place to go, but the cells aren’t letting it in. As I’ve explained before, insulin is a GROWTH HORMONE – it grows muscle and fat cells.  Those who struggle with weight, usually experience the latter and have insulin resistance.

When we take in more glucose (carbs), the thyroid increases circulating T3 as well. So there’s an inverse relationship:

(^ Glucose = ^ T3 / v Glucose = v T3)

…so don’t panic if your T3 goes down on a low carb or Keto Diet. Lab values and even functional lab ranges are NOT based on the ketogenic/fasting diet population – they’re based on the average population (which is usually unhealthyl and carb-based – especially here in the US and in most modern cultures),

The body makes its own glucose – it can convert protein and even fat to glucose, but if you’re eating a real food KETO diet with a good amount of non-starchy vegetables, you’re probably getting plenty of glucose substrate to fuel the T4>T3 conversion.  In terms of priority, as a hypothyroid individual (which I am), I’d definitely put my focus more on the  implications of insulin resistance by eating too many carbs and not worry about getting enough dietary carbs “just in case” for thyroid conversion. – especially if I feel so good!

On the topic of Hashimoto’s with Keto and Intermittent Fasting, again, we have a good case for both:

• Keto is anti-inflammatory.  We know that autoimmunity is rooted in inflammation.
• Keto and IF are gut friendly which is the cornerstone of supporting the immune system.  Because carbs are reduced significantly and we tend to eat less often, the gut gets a nice break from using all it’s energy to break down and digest foods when we eat and graze all day long (as sugar burners). This allows for more repair and less assault from more inflammatory foods.
• The microbiome (gut flora) is also more supported with less of a load from sugars and starches which tend to be a primary cause of dysbiosis (bloating, etc..) and leaky gut. A balanced microbiome and an ‘in-tact intestinal lining’ are critical for immune regulation.

Here’s what to look out for if you’re thinking of going Keto or fasting and you have or suspect thyroid issues:

1. Make sure you’re eating enough (and not too much if you’re trying to lose fat).  Caloric restriction down-regulates thyroid function. Keto reduces appetite because fat is so satiating. Also, being Ketogenic balances blood sugar so cravings and hunger hormones come into balance.  And although we want to encourage the body to use it’s stored energy (body fat); in the beginning, most people do better if they become fully fat adapted before they start cutting fat calories.  Keep the total carbs under 30 grams (from only non-starchy veggies – some do best with 20 grams, some can go higher), get about 100-ish grams of protein  (give or take) and get the rest from fat until satisfied. After a month or so when you’re feeling really good, you can start to gradually cut fat intake if you’re not losing inches.
2. Go Slow.  Drastically cutting carbs and restricting your eating window is likely going to be perceived as a stressor to your body.  You need to take it slow because that stress will impact your adrenals – which is like eating donuts – I’ll get into all that in Part 2.
3. Ensure you’re getting all the thyroid co-factors to support thyroid function: Iodine, Selenium, Vitamin D w/ K, Magnesium, Tyrosine, Zinc and B vitamins.  Also Fish Oil and Black Cumin Seed have been shown to improve thyroid function and weight loss in people with thyroid issues. You can supplement, but also be sure to eat nutrient dense foods like wild fish, shell fish, sea vegetables/seaweed, pastured eggs and meats, Brazil nuts, spices and herbs, greens/cooked goitrogens like kale and broccoli (goitrogens inhibit thyroid function – but not if they’re cooked).
4. Most importantly! Honestly Check In with how you feel on Keto and/or with fasting. If you don’t see improvement and especially if you feel worse – you may need to make adjustments or this just may not be for you (feel free to connect with me if you’re not sure).

Questions? Do you have experience with Keto and Fasting with thyroid dysfunction or hormonal imbalances? Share below or with me directly. Stay tuned for Part 2 – all about the adrenals and stress.