Change in body composition and dosing of thyroid meds

[Wired123]

Hi all,

I wanted to pick the brains of the technically-minded on here.

I think we are all familiar with the notion that dose needs to be reduced as one loses weight as less mass = less need for hormone.

I’ve been losing fat but replacing it with muscle so my weight in KG has hardly changed, however by shirts and jackets are much much looser. So I suspect I’ve lost around 1 stone in fat and replaced with a similar amount of muscle.

Would my dose be expected to stay the same or would higher amounts of muscle require an even greater dose vs the same weight of fat?

I’m not due for another blood test for a few more months so won’t know for sure until then how my bloods are looking.

Any advice appreciated.

I’m on 150mcg T4 and 15mcg T3 daily and weigh 106kg.

[Lalatoot]

Wired, if you have changed fat into muscle does this mean you have greatly increased your activity levels and altered your diet?

Our dosages also reflect our activity levels. A change in diet might affect gut activity and alter absorption. A diet change could also improve vitamin levels.

On the internet there is also a paper discussing dosage by body mass rather than weight which is relevant to your question. ncbi.nlm.nih.gov/pmc/articl...

[Wired123 in reply to Lalatoot]

thank you, yes I’ve lost fat and added muscle - but weight approx the same. Been achieved through a combination of diet and exercise, so you’re actually right there’s multiple things in play here and not as simple a question as I first thought envisaged.

I’ll take a look at that paper tonight, thanks again for your insights!

[HowNowWhatNow]

how did you manage to gain so much muscle? And how do you feel now? Different?

[Wired123 in reply to HowNowWhatNow]

I do weights sessions 3 x per week with a very good personal trainer. It was a slow build up and started as 1 session a week. He’s pushed me at the right times and I’ve also massively increased protein intake (meat and protein powder). I also cut out a lot of bad stuff from the diet, particularly reducing carbs and cutting out wheat (wheat was a big source of problems).

[Wired123 in reply to Wired123]

note that carbs are reduced, not completely cut - I’m not on keto.

[HowNowWhatNow in reply to Wired123]

well done.

[cazlooks]

I don't have an answer, just want to say I'm impressed! Well done.

[FAB-jellybean]

Well done Wired123 ! I too started weight training around 3 years ago as a means to self-manage my fibromyalgia pain. It has definitely made a huge difference. Also eat more protein than I ever had and have gained muscle over fat. I am also still around the same weight I was previously but body composition has changed (73kg). I hadn't even thought about this aspect but fast forward to June this year and I was feeling really poorly again. Blood tests showed that I was quite under-medicated. I rather stupidly hadn't tested for a couple of years. I increased my thyroxine by 25mcg a day and it improved but still not optimal so have added another 75mcg a week and will test again shortly. I had added HRT patches 18 months ago ago which are supposedly not meant to affect thyroid levels as much as oral medication but I was blaming that for me needing additional thyroxine. You've now made me realise that it probably was my change in body and activity levels and I can't believe I didn't think about it myself. So thank you for that.

As far as testing goes, you have a good reason for requesting an earlier test if you don't want to go the private route. I would advise you make sure you get your T3 and T4 tested though as that was what let me see how undermedicated I was. The other question though, is how are you feeling? My decline was so gradual that I didn't properly pay it any attention until it was making a marked affect. And now am having play the slow wait game for everything to settle back down. All the best.

[london81]

I realise now that a couple of years back when my thyroid levels crashed despite being on ndt ot might have been due to starting back using weights. I had a dexa scan which showed really high muscle but same level of fat ( too high, and combination of fat and muscle meant i looked too heavy plus was so hungry i couldn’t control my weight). It sounds like you have done really well on this regime and congratulations on gaining muscle! I suppose you could do a test and monitor your symptoms as the simplest way to monitor what dose you need. you could get a dexa if you were interested in exact breakdown of the muscle vs fat ratio too