Thyroid UK

Water fasting - meds?

I'm hypo and pretty stable on 75mcg triyotex now. I don't seem to gain weight as insanely quickly as I used to, but I am 5 stone overweight and finding it hard to lose - I've also come to terms with the fact that it's my terrible eating habits at fault and not my condition. If I can binge eat I will binge eat.

I heard about water fasting last week - living on nothing but water for 7-21 days - and I'm very intrigued. I would like to try it. If what I've read is true, I could lose nearly half the weight I need to lose in less than a month, and then just build on that. My diets tend to fail after 2-3 weeks so timewise it would work for me, and I might actually enjoy eating lettuce and fish for a while, after nothing!

My query is about my medication. Should I gradually reduce it during that time? There's all this stuff about how your body gets down to focusing on other things while your digestive system is at rest, and I'm wondering if that could possibly include complex things, like the thyroid?

I would be really interested to hear if anyone has done the water fast or has heard good (or bad) things about it, particularly about how it can affect the thyroid. Thank you!

7 Replies

Dieting/Fasting severely affects the thyroid - so do take care. It is an Ancient mechanism from the days when we were nomadic - living in caves and only eating when food was available. When food was not around - then the thyroid would slow down to conserve energy. This mechanism is still in place today. Our brains have evolved and increased hugely - however the Endocrine System is still the same as it was when we got up on two legs and left Africa turning left at the top :-) - or whatever you believe in.

Maybe have a full thyroid Profile tested - TSH - FT4 - FT3 - Anti-TPO - Anti-TG - and post your results in another post for people to comment. I am suspecting that your FT3 is low and that you could do with a boost. Or is the medication you are on a T3 product - sorry do not recognise the name.

The reasons your diets fail after 2/3 weeks is possibly due to reasons I have mentioned in the first paragraph....

Sorry not able to comment on the Water Fast - doesn't sound good to me - sorry :-(

1 like

Water fasting may be o.k. for people with no autoimmune/metabolic conditions but I would be wary.

Usually, if we are on an optimum of medication if hypo (we have no symptoms and feel well!) dieting can be helpful.

Do you have your latest blood test results with the ranges? If not request a new test and request T4, T3, Free T4 and Free T3 (they may not be done but ask anyway).

Leave approx 24 hours between your last dose of levo and the blood test and take it afterwards.

Have the earliest possible blood test and fast (you can drink water). If you've not had B12, Vit D, iron, ferritin and folate tested ask for these too.

Get a print-out of your blood tests with the ranges and post on a new question for comments.

The addition of T3 to your T4 might well be advantageous to you as T3 is the Active hormone and can raise our metabolism. Page 80 on the l/hand side states that it was found that a therapeutic dose was 1 T3 to 3 T4.


The trouble with doing severe dieting like this one is that it causes your metabolism to down regulate. This is natures way of surviving famine. The body in order to survive and preserve it stores sets itself so it needs less fuel/food energy. This means that when you start eating again you will more quickly put weight on again. it takes sometime for the body to adjust to it being down regulated. This is why they say yo yo dieting doesn't work. I think you need to box more cleverly to outwit this mechanism.

Firstly are you on the optimum dose for your thyroid? As the others said get bloods done and post on here.

Personally I wouldn't think about dieting until you are optimally treated. In the meantime trying to stick to a healthy diet with lots of slow release foods such as protein & veg with some carbs -fruit at the end of meal not separately (to stop insulin spikes) and avoid added sugar including 'natural' such as honey. Add gentle exercise such as walking with a pedometer to boost up your metabolism which will run slow because of the hypothyroidism.


I am no expert but have to admit that is something I wouldn't begin to consider as I'm asking myself ....Where would my energy come from when only taking in water ?

Years ago,hubby and I did a detox with no tea,coffee etc.Within 24 hours we both had the most awful migraines.

However,I have often thought of going back to drinking only water, as when we did it people commented on how well we looked,but would also eat sensibly at the same time..........I would add that at that time I didn't have thyroid problems.


GentleOrange, it sounds positively dangerous to me. I think you need expert help to deal with binge eating and a structured eating and exercise plan to help with weight loss.


I managed to lose 24lbs on the 5:2 diet but ONLY when I was optimally medicated. It was critical for me to get the medication correct otherwise, diet or no diet, the weight did not come off.

With my holistic hat on, it sounds almost as if you are wanting to punish your body - for what? If, as it sounds, you have an underlying medical problem it will not be helpful to starve yourself. As I tell my clients - "be kind to yourself". It is amazing how often we are not.


My feeling is that a lot of my issues could be dietary, and I want to see if a therapeutic fast could help in that area. I'm halfway through day two, feeling really good so far and still taking the T3 - but I may start to reduce it in a few days and see if I feel worse or the same.


You may also like...