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Thyroid UK
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Still gaining weight on T3

I have been taking 75mcgs of T3 only for two and a half years. I have felt almost back to normal on it but I cannot lose weight. In fact, I am steadily gaining it! I take iron and all the supplements I am supposed to for good health. But the only way I can stop the scales steadily creeping up is to eat one meal a day. This leaves me miserable, as you can imagine. I am quite fit and walk between twenty and twenty five fast miles a week with my husband and our dogs. I am utterly mystified as to why my weight continues to creep up. Can anyone shed any light on this, please?

18 Replies

What is your TSH result and do you take iron at lest 4 hours apart from T3.


Thanks for responding. My last TSH result was 0.04 and I take all my thyroid tabs together at seven am and wait an hour before food and drink. I take my iron at night.


Hi fortunate,

Have you tried eating 4 / 5 small meals spaced throughout the day. This keeps the metabolism ticking over and uses calories continuously .

In effect, what is happening with you, is that your body is going into starvation mode. It will conserve the fat and you will lose muscle first.

I know you probably will be afraid to try this method but it does make sense. Just graze on healthy food to kick start your metabolism.



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Thanks for your reply, Jose651. I will certainly give it a go. I feel like my metabolism is broken!


You're definitely doing the correct thing re meds. I tried the 5;2 diet in the summer and it wasn't difficult (mind you I am retired) so don't need so much energy. I found it quite easy to do because I could choose any two days in the week and you eat no more than 500 cals a day. (I know 500 cals isn't much) but you don't have to diet every single day or watch your food intake so you can go out with friends or switch your day if necessary. If you choose some filling foods beforehand and you know the next day you can eat normally it's much easier. I was happy to lose over 3 months (12 weeks) sufficient for me.

Another member didn't do well on the 5:2 but ate a high fat diet. I'm not sure how that works for every day.

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Thanks, Shaws. I think I'll try the 5:2 diet before I try the four or five small meals a day approach. I'm good at going without good, having been used to only eating one meal a day. 500 cals a day twice a week should be a breeze!


Going without food, I mean!


That makes it a lot easier. I didn't bother weighing very much - only measured around my waist which was my 'target'. Lost 7 inches but also lost weight too.


Forgot to say that the 5:2 is really a 'lifestyle' rather than a diet in that it can last a lifetime, i.e. when you reach a weight you're happy with, you only need to do a 1 low cal day per week which keeps you in line.


Hi, I know a lot of people who went on the 5:2 diet and lost huge amounts of weight and looked great (which is what we all want!) but I have to say they have ALL, bar none, put it all back on AND MORE as they found it hard to keep up. I don't believe in diets but eating everything in moderation and have done a lot of research and it keeps coming back to this over and over again....the smaller meals more frequently makes a lot more sense for a thyroid patient but as ever there is not one rule that applies to all, everyone is unique, you have to find your way but I think that way sounds a good way to start personally...good luck (and sorry for the contradictory advice, I understand it's all a bit much with all this 'advice' and it's hard to make a decision so going with your gut instinct, as long as you're listening to it properly is the way forward!)

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'I take iron and all the supplements I am supposed to for good health.'

Who said you were supposed to? And did they say how much you should take of each? Or are you just taking a multi-vit and crossing your fingers for good luck? :)

One should always get tested before taking anything. A pot-luck approach is often just not good enough. You need to know where your deficiencies are, and how bad they are, before you can know what to take and how much.

Best to start by testing vit D, vit B12, folate, iron and ferritin. However, if you've been supplementing with with Bs, best to stop them for two months before testing B12 and folate.

Our nutrition needs to be optimal for us to be able to use the thyroid hormone replacement we're taking - even if it is T3. Do you have any thyroid labs to share with us - apart from TSH, which on its own, isn't adequate? It could be that 75 mcg just isn't enough for you.

Take care.


I would not take supplements and just 'cross my fingers'! I take the ones I was tested for, which were found to be low.

My last test showed my t4 was non-existent, as I knew it would. My t3 was 4.71 The range was 3.6-6.5.

My temps range from 36.1-36.7 and pulse rate is usually about 51 when I wake.


Well, then, why didn't you say you'd been tested for them and what the ranges were? If you leave us to just guess these things, we're going to come up with some pretty weird conclusions! :) All the détails count.

OK, so no mystery. Your T3 is still too low. You're not going to lose weight until it's a lot higher.


I think Greygoose is right and you need a bit more t3 for weightloss.

Jo xx


Fortunata, have you had FT3 checked? Overmedication can cause weightgain.



I do sympathise but I wonder if you are optimally medicated. Maybe you just need a tad more.

Walking is great exercise but it's NOT great for fat burning. It is cardiovascular.....gets the blood pumping and the heart beating nice and steadily.

By far the most important aspect of losing weight is Diet. A good 90% of our weight is about what we eat.

The gym culture has mislead and misguided many. It is great Business! It has lead us all to believe that if we're not pounding every joint in our bodies relentlessly then we will never reach our target weight! ....utter RUBBISH! What it IS doing is keeping the orthopaedic surgeons busy!

So.....if you are optimally medicated then it can only be diet.

Eating one meal a day will shut your metabolism down to a standstill. It is already compromised with your hypothyroidism. Simple changes will make a huge difference.

LOW GI is the way forward. Foods which your body has to actually work hard at digesting!!

3 meals a day with 3 snacks in between.

RICK GALLOPs books are fabulous. A very easy read and fool proof.

Starting the day with a bowl of porridge will immediately crank up you metabolism. Proper porridge!! Large oats which your body must work hard to digest. Not ready break or quick porridge.

If it's been refined...DONT TOUCH IT!

It is simple maths. The more the food has been refined in a factory the less your body has to do to digest it.!


Im not sure if your t3 weight gain resolved..did you find out if you were on too much or too little? I too have had a huge gain on t3 only. 9 pounds in 5 weeks! People do try to offer get your iron checked change your diet etc but i dont think they get the clear absolute of how t3 in some if us just piles on the pounds. In my 9 pound gain ive developed rolls of fat on my back! My stomach went from flat to huge! I have a pouch now that sort of hangs down over pubic area. The t3 is the only culprit and why why why when the rest of the world loses weight on t3??? Im still trying to find answers to this and what to do. Yes the t3 helps me feel better than i have in years, more like my pre thyroid disease self but my lord the weight gain from it is chronic!


Hi, there. I have managed to lose weight by eating a ketogenic diet and feel much better than I did when I wrote this original post.


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