Today I am coming to you with a deep dive into the super-popular (and controversial) subject of fasting with a thyroid condition. A big NO, or something you should seriously consider? Let’s find out!

The Science of Fasting and Thyroid Health

Fasting has become such a hot topic you’ve probably been tempted to try it. But then you Googled thyroid and fasting and saw all the fear-mongering and how fasting (any type) is a really bad idea.

And as with most things, the answer is… IT DEPENDS.

Fasting, done incorrectly (and by that, I mean not taking into account your gender and thyroid issues), can lead to problems with thyroid hormone conversion, cortisol spikes, and messed up sex hormones.

When you do it right though… it has the potential to change the trajectory of your healing (and weight loss journey), boost your metabolism, improve metabolic flexibility, stabilise blood sugar and help you live longer. It is the most natural way of eating, if you think about how our ancestors used to do it when food wasn’t readily available all the time. Our genes and biology haven’t changed that much since then, and the fact is you are not designed to eat (and digest) all the time. All sorts of repair processes and positive changes are happening when we cease the food supply, and there’s more and more research emerging on the benefits of fasting.

Also, anticipating your questions, fasting ‘scarcity’ is very different to dieting ‘scarcity’, when we create a long-term shortage of calories and nutrients, and it has the opposite effect on your metabolic rate.

​Key benefits of fasting:

• Insulin Sensitivity: It can enhance the body’s ability to use insulin effectively, reducing the risk of type 2 diabetes, and lowering cholesterol and blood pressure.
• Balance Blood Sugar Levels: Regular fasting periods can help stabilize blood sugar levels which will work wonders for your inflammation levels, cortisol and energy throughout the day.
• Reduced Inflammation: It has been shown in numerous studies to decrease systemic inflammation
• Autophagy: This is the body’s way of cleaning out damaged cells and regenerating new ones. Fasting enhances autophagy, which can help prevent diseases and slow down the ageing process.
• Weight loss: Fasting increases our metabolic flexibility, where we switch to burning fat as fuel, lowers insulin and speeds up metabolism, making it one of the most effective weight loss tools (but again only when done right).

​Types of fasting:

What I recommend for everyone is TRE (Time Restricted Eating). Meaning, you don’t eat between dinner and breakfast (minimum 10 hours). This way of eating is gentle on the body and also provides massive benefits for our blood sugar, insulin inflammation, but also leptin and circadian rhythm.

And then we have other types of longer fasts like intermittent fasting (typically 8h eat, 16h fast), 5:2, and extended fasts like 24h, 36h and longer! (24 hours is the longest I recommend, and I include training on different types of fasts in my UNDIET programme).

Important Considerations

If you would like to safely add fasting to your healing toolkit, here are a few important things to remember…

1. You can’t fast your way out of a bad diet. The foundation of thyroid-optimising nutrition must be in place before attempting any fasting. Knowing how to ‘break’ a fast and how to structure your meals in a shorter eating window is key.
2. If you have a cycle, you must be mindful of that. If you’re a woman, you can’t fast like a man. One of the main rules is that the week (approximately, depending on your cycle length) running up to your period is a no-fasting zone. 
3. Don’t launch yourself into a 24h fast or even 16h fasts, it’s all about getting your body gently accustomed to this process.
4. There’s more than one way to fast. For some, the morning fast might be better, but for most women with thyroid and leptin issues, evenings may work better.
5. Whatever you do, please, please don’t have coffee and exercise in the fasted state.
6. Listen to your body. It will tell you what is working in alignment with your body and what is actually stressful and far from beneficial right now.
7. You should not fast if you’re at the very beginning of this journey and your fatigue and other symptoms are through the roof. You will likely still be able to add it, but first focus on the foundations – optimising your nutrition, lifestyle, and habits, and regulating your nervous system. I encourage you to check out my foundational course Thyroid Fundamentals and my signature Root Cause Programme BLOOM before joining UNDIET.
8. If you know that your cortisol levels are higher than where they should be (you’ve done the functional test from urine or saliva), I would avoid fasting and focus on TRE and prioritising the nervous system work. You can always introduce it once your cortisol levels are in a normal range (a note here: I have done hundreds of these tests with clients and see an increase in cortisol very rarely so don’t assume this is you, despite what the internet tells you)

Fasting as a tool for Thyroid Health

​I have personally used intermittent fasting for 7+ years, and see it as one of the biggest needle movers on my own journey. As you know, I am in full remission and almost two years ago, I successfully got off levothyroxine. I hope learning more about fasting has inspired you to try it!

I would absolutely love to guide you through this process as a part of a comprehensive metabolic reset journey. You can do that in UNDIET Self Study to help you tailor your fasting plan and safely introduce it into your healing journey.