Thyroxin and not being able to lose weight

In preparation for my 65 year old health check today, I did some research on this site and was shocked that GPs and other health professionals have never mentioned the relationship between T3 and T4. I have been taking thyroxin since 1994 and am currently on 200mcg a day. This was because some years ago I upped my dose from 150-200mcg based on a book on underactive Thyroid which suggested this would increase energy and weight loss ! My health test was fine today apart from the fact I am clinically obese and although I have been attending weight watchers and slimming world, I struggle to lose any weight. I would welcome advice on wAy forward - thinking of 1) reducing thyroxin to 100mcg a day 2) see GP and ask to be referred to endincrinologist re prescribing T3 3) get blood tested for T3 and T4 as a year ago only tested for T4

Any other suggestions?

60 Replies
oldest β€’ newest

I would buy a blood sugar meter and take blood sugar readings for when you wake before meals and 1 hr 2 hr and 3 hr after meals and before bed. - do it for 10 days I did not realize I was insulin resistant- I found that I had to give up gluten free oats, add more fat ( avacado, hemp hearts, olive oil) - not eat after 5 pm ( surprisingly strawberries, rice and sweet potatoes also spiked my BS) anyways I did intermittent fasting- avoided all sugar and now test my BS in the morning intermittently- I have my morning BS down to 4.5 and it rarely goes over 5 when I eat.. I thought I was eating healthy but I was not for me- I also found during the intermittent fasting that broccoli- cauliflower - chicken - turkey causes slight weight gain - I'd weigh myself in the am - these foods causes inflammation so now the only protein I eat is egg and fish-- inflammation is the source of all weight gain -

You are not alone with this problem. I struggle to lose the weight as well. My doctor tells me it's the thyroid condition it's self not the medication, which seems more depressing. The 5/2 diet was recommended to me for people with thyroid problems but it just kept my weight stable. I am going to try low carb next as something has to work!!

5-2 worked for me...but it was slow... some weeks losing nothing...but over 7 or 8 months I lost 6kg. I find it easier than trying to cut out something every day of the week... and that is where I usually fail.

I have only lost weight when I came off Levo and went to Nature Throid. I did this because it includes T3 and I realised this could not be prescribed. Have lost a stone since Feb this year. janveron

Hello Montheone

I am about your age and I have been on T4 thyroxine for almost 40 years. Up until about a year ago I also found it really difficult to lose weight because being hypo means your body is not metabolising as it should that is, it is really slow and it is that which probably accounts for weight gain(at least in my case). However, about a year ago or so I started adding 10 mcg twice a day T3 to my 150 mcg T4. Now the point of doing that was because I was hypo and I wanted to see if I could get over my brain fog, fatigue and feeling cold all of the time. However, I also found that I was beginning to lose weight even though previously I was going to the gym 5-6 times a week and being really careful with my food intake. So I have lost about 2 kilos this year, it has been slow for me but I decided to try and lose it the same way I put it on...slowly. So that works for me. I am in Australia and I can get tsh, T4 and T3 tested but that will depend on where you are living. I can also get T3 easily as well for $AUD 37 for 100 tabs x 20 mcg. So all I can say is that an unintended outcome for me re T3 was some weight lose, but I have also had relief from my other hypo symptoms.

I am the same never could lose weight no matter how hard I tried , so I self medicated with T3 and i felt alot better in myself , lost weight slowly but it was coming off ... all the doctors I saw said I didn't need it ....last blood test the doctor didn't like the fact I was taking T3 and asked me to stop and have another blood test done and if needed he would up my T4 ...I stopped my T3 and my weight has started creaping back up and I've not felt as good as I did on T3 I've had my blood test done yesterday and SOD the Dr I'm re introducing my T3 ......I know he won't prescribe T3 or up my T4 .....I'm doing what I feel that makes me feel good .

Are u in the UK ? Do you buy your T3 where from ? Mx

Fron Turkey but can't get it anymore

I'd be really careful about self-medicating. A levothyroxine or Synthroid overdose can actually be lethal, and most people won't realize they're doing it until they wind up in the hospital. My pharmacy screwed up my prescription, instead of 25 mcg, they gave me 200 mcg. Sure, I felt great, and lost weight like crazy, as much as a pound a day! As anyone else who's battled weight gain as long as I have you know how that boosts our mood! Then my latest lab tests came back. I was taking what could have easily turned into a toxic level and I wouldn't have known it until I went into a coma. My doctor stopped the meds immediately. Too much thyroid hormone affects everything, and when I read the list of overdose symptoms I was stunned. All the symptoms I had attributed to withrawal from thyroid hormone supplements, were actually big red flag warnings of a dangerous overdose. Please, be careful! Final word, read the label on your prescription bottle. That was how I found out how much levothyroxine I was actually taking. If you aren't happy with your doctor, see someone else. Good luck

RoseMcD I believe Karen Carpenter took huge doses of levothyroxine it still took quite some time to kill her.

Sensible self medicating with gradual titration is not dangerous, it is not ideal either and I agree care should be taken. We would nit be doing it if our stupid medical profession would offer a choice of hormone replacement therapy.

It is interesting that you were not self medicating when you took almost 10x your correct dose.

Yes I agree you gave to be careful with medication. ..I'm going to see the Dr again next week for results ...T3 only taking quarter of tablet

Another issue we have to be really careful about with our meds is one we have to keep an eye on. Literally. Our prescription bottle labels. I had some serious problems after my MD stopped my levothyroxine because of a really alarming set of lab results. Turns out the lab results were accurate. The problem was shocking. Someone in the pharmacy filled my prescription (25 mcg) once a day, with a dose level of 200 mcg once a day; eight times what had been prescribed. No wonder the lab tests results were through the roof! The symptoms were a consequence of having too much levo in my system, and the really scary part is that an overdose of it can be lethal.

My advice, check your labels!

Amazing, isn't it? What a little T3 will do!

The whole problem with the human condition and illness in general is all due to low T3 in the cells. Usually, doctors don't even test Free T3. They use TSH, which only indicates that the person isn't activating more thyroid hormone as the TSH says it is fine.

But TSH is only a meter for the pituitary gland. What it doesn't tell anyone is how much of the T4 being stored is actually being converted to the active thyroid hormone that is the life force of the body: T3. It is easy to monitor. But few do it. Unimaginable in the 21st century.

It's the most important test for anyone who is not responding to Thyroxine (T4) replacement. If you're not getting better on T4 then either the dose is too low or you're not converting it into T3 at a pace sufficient for all the cells to have an optimal supply of it. When T3 is low, people eventually die.

We really don't have time to waste with incompetent doctors who don't understand how the body works. It's definitely not rocket science!

The study below is very interesting. This has been known for quite some time that Low T3 always equates to malfunction and illness. The study was done on elderly people who were low in T3 and what happened to them. It is painful to read because their deaths did not have to occur.

The other reason it is so painful to read this is that conventional medicine does not recognize what this study (and others like it) proves: we all need adequate T3 in every cell of the body for proper functioning of all organs and systems. If not, T3 is taken from other non-vital areas of the body and eventually those systems and organs begin to fail. That is when the body slowly dies, just as the people in this study who all had Low T3.

It couldn't be clearer.

I switched from synthroid to desiccated two years ago. Huge difference in energy level, brain fog. First time in years my T3 is in range. Weight still an issue. Have been hypothyroid for 37 years. I see a personal trainer, walk, eat organic etc. My sin is the occasional red wine. Always fight the scale. But I now have the energy to do it with desiccated

Is this expensive? Are u in the UK ? Is your doctor OK with this? Mx

If she was on synthroid it means she's not in the UK.

I'm in the UK I paid around Β£8 for 30 tablets but can't get them as did before have to send bankers cheque and I've never done that before and feel little edgey doing it

I think you should. Ertainly get your T3 tested, look at Blue Hotizon and Madichecks. Both have offers from time to time and useful to get folate, ferritin, B12 and Vit D done at the same time then post your results and ranges for. Onments. You may not be converting well or may be on too low a dose but with results then it's easier to give advice

First of all, stop dieting. It has little to do with what you eat, and lowering your calories will have a negative effect on conversion, making you more hypo. Let's forget the weight for the time being, and find out what's going on.

Secondly, yes, you do need the FT3 tested, but not just that. You need :






vit D

vit B12



Once you have all those, you'll have a much clearer picture of what is going on, and where to go from here. There are so many possibilities - an absorption problem, a conversion problem, Hashi's, nutritional deficiencies, gut problems, low stomach acid etc. etc. etc.

Unfortunately, the NHS will not do all those tests, so the best solution is private tests.

Reducing your levo to 100 is not a good idea. For one thing, it's too big a jump in one go - reductions, like increases, should be 25 mcg every six weeks. Secondly, it would make you more hypo and you'd put on more weight.

Seeing an endo is not necessarily a good idea, either. Most of them know little about thyroid, and you could find yourself in a worse position than you are now. And, it's highly unlikely that they're going to prescribe T3 - or your GP is going to prescribe it, even if the endo says so.

If you really want to see an endo, email LouiseRoberts for her list of decent endos. But, first of all, get the above tests done, so that you have a clear idea of what is happening, and what you want, so that you don't get fobbed off.

If I could double like this reply I would. x

Thank you. :)

Me too, I have always found the advice from Greygoose extremely good. I managed to get T3 prescribed and now take 40mcg + 50mcg levo. My aim is to cut out the levo altogether and add another 10 of T3. I lost two stone over 18 months when I got the T3 and I eat 2000 cals per day roughly.

Very well said.

Thank you. :)

Thank you so much - I have printed this off so I can study it - will report back after I have had a private test mx

I'm not in the UK; we can't order our own lab tests; we have to have an MD who'll order for us. General practitioners rarely order the full range of bloodwork, but a good endo will do it as a matter of course. Note..a good endo. I've been on the find a good doctor merry-go-round since 2015, finally found a good endo whose office is only about a mile or two away. She ordered every test known to God or man. Waiting the results.

OK Do you think you could mention on you're profile where you live? It would avoid future confusion. :)

I'm in the U.S.

Yes, I realise that, now. But, if you could put that on your profile, it would help others in future. :)

Ive changed from 125 mcg t4 gradually to 30mcg t3 and 50/25alternating days of t4. At long last Ive started to lose weight. I feel good on this combo. I think Im going to get greygooses suggested levels checked soon. I was lucky my endo has given me t3, but all they check now is my tsh level. You will bet better advice here than from any gp. Good luck x

Who is louse R how to get in touch with her.


Have a look at this page:

Thank you

I'll leave other, better qualified, posters to consider dosages. But I learned a few things on T4 which allowed me to lose 5 stones - very slowly! - with SW.

Despite what SW says, carbs and low thyroid do not mix. I very seldom eat pasta or bread and keep potatoes low, choosing baby new ones where possible as they have less carb. Cake and biscuits are a no no. Ditto sweets. I choose lower carb fruits.

I also drink lots of water because fluid retention is also a thing.

Smaller meals regularly is better than blowouts and starvation. Atkins and 5:2 work fine but don't go berserk on the 5 days!

Keep active. It shapes the body and what you have looks better.

Above all, persevere - this will be slow. But IT CAN BE DONE. Wishing you the very best of success. Let us know how you get on.

Very low carbs, like the Atkins diet, can be bad for hypothyroid people. You can give up having rice/pasta/potatoes with every meal, but cutting down completely can make us very ill.

Carbohydrates are part of the process of metabolising thyroid hormone.

I can only say that my experience had been different and that's what I offered. Of course, nobody could cut out carbs completely and that isn't what I said. But for me this worked after years of failures. I guess we are all different.

My experience has been different too.


I beg to differ. I could not loose an ounce on levothyroxine yet within days of starting to switch to NDT (so only a very small initial dose and equivalent less Levo) the weight evaporated and I felt like me again. It was no effort just like it had been before becoming overtly hypothyroid. It must be the T3 normal human thyroid glands do not just make T4 they make T3 as well it must be for an important reason, not to mention the stuff they make that is dismissed as of no consequence whatsoever. I just don't buy it - they are not even scratching the surface of understanding this disorder or the true role of what a properly functuining thyroid gland makes or what all this stuff actually does or how it does. I often wonder if those who feel ok on T4 would feel even better on NDT. Some studies seem to point to a majority preferring it against very few for T4 monotherapy. I would never go back to levothyroxine. Keeping ones body at its optimum weight should not be a fight it should be easy in fact not even something that needs attention. Struggling with ones weight implies to me that something is fundamentally wrong at a metabolic level.

Mind you I take my hat off to you for succeeding!

I think it is a personal thing. Mind you, since this I've become T4 intolerant and I'm now on T3 only - and finding it harder to stay this weight! Horses for courses eh!!

scorp1o gosh how odd that T4 worked better for you than T3 fur weight control. Bad do with the intolerance. I guess NDT is a non starter for you too. I think you are right we are all so individual - all the more reason for a proper choice in treatment options so we can each find our best possible health with this darn disorder.

Amen to that. I've had to fight tooth and nail for T3. Good luck to you.


🎩 🎩 πŸ†™πŸ†™

I agree with the wonderful post from grey goose. You need to find out what else might be going on. A few years ago I didn't feel right, I couldn't shift extra pounds despite eating healthy and doing enough exercise. I presumed that it was thyroid that wasn't medicated properly so I was pushing Drs to change my medicine/dose. A new dr then realised that my vitamins were all low despite taking supplements and he diagnosed Coeliac! Now that this is healing I can eat well and stabilise my weight as my gut is working properly.

My advice is be open minded - it might be something else. By starting with blood tests it could help you get a better picture of what is going on. Be aware though that it can take some time. It took over two years for me to get my answer - so don't give up :)

Weight gain is the commonest question on this forum and it is due, mainly, to being on levothyroxine alone which, if not an optimum dose, metabolism is too low and weight is gained. The addition of T3 (not now prescribed in the UK) is the only active hormone required in our billions of receptor cells to driive our metabolism. Look on the cells as 'energy'. Free T3 and Free T4 are rarely taken and I'll give you a link and you'll see the reason. Look down the list to FT4 and FT3.

Exercising whilst not on optimum thyroid hormones reduces what T3 we have and doctors seem to put the blame on the poor patient as they know nothing about how thyroid hormones work. Even before we are diagnoed we can gain weight due to low thyroid hormones. It is a clinical symptom and I'll give you a link and tick the symptoms you have. Some doctors disparage the patient and make them feel it is their fault due to a bad diet. Not true at all.

We have to self-educate and cannot be angry with doctors due their poor training (it would seem to me) they appear to know nothing about being on too low a dose. Knw no clinical symptoms. The method of diagnosing - in that the TSH has to reach 10 (in other countries it is around 3+) is far too high and people suffer and have lowish TSHs.

Blood tests have to be at the very earliest possible, fasting, and allow a 24 hour gap between last dose of levo and the test and take it afterwards.

If you've not had B12, Vit D, iron, ferritin and folate tested ask for these too.

There are tests for T3 and T4 but it is Free T4 and Free T3 which is better as it gives members a better picture.

Research by several different Researchers have proven that most feel better with a combination of T3/T4 but in the UK, they will not prescribe T3 anymore which only proves even more that the Professionals aren't so professional.

Always get a print-out of your results for your own reords and post if you have a query.

Your post is excellent Shaws so please excuse me for drawing attention one little error. I have just been prescribed T3, in January, and my surgery is going to continue with it. My GP is supportive of this and a special case has been made based on my blood test results, not weight nor just how I feel.

That's what the guidelines states 'depending on clinical need' but many have had T3 withdrawn and been given unwarrented anxiety.. I am glad you have a kind doctor

I am also 65 and only 5' 1" - always was a size 10. got treated for a overactive thyroid and slowly gained 2 stone. the doc didn't put me on levo right away as he said my readings weren't high enough only borderline. eventually went very hypothyroid and put me on levo. after 6 months even more weight went on - in spite of trying every diet under the sun - nothing came off. after researching this site and demanding that docs test my t3 (which was low). they said my weight gain was because of my age. they just came up with all the usual stupid excuses. I then decided to go on thiroyd. I was a bit apprehensive at first but started taking it and dieted and lo and behold the weight is coming off. I have lost one stone so far and another one to go. I believe that levo just increases weight gain for some - at least it did for me. I feel so much better on natural thyroid. good luck

One thing I've learned is that with something as tricky as thyroid problems, it almost doesn't matter how good your primary care doctor is, or how much you like him or her, they just don't have the additional training needed to deal with our endocrine system. Go ahead and make an appointment with a specialist, and a word of advice from one who learned the hard way; don't let a misguided notion of loyalty to your primary care doctor stop you. A good doctor wants you to be healthy, and will NOT be offended if you see someone who specializes in what ails you. Good luck!

But do as Greygoose suggested and get the list of doctors and endos with a clue from, as most endos seem to be diabetes specialists,

Does her list include U.S. doctors or only U.K.?


I'd like to add to Rose McD's good post - if your first endo dismisses you with 'increase your Levo' as mine did, come back onto this site, find a good endo and ask your doctor for a referral. I travel over 100 miles to mine but it's worth it.

Worrying about calories is fruitless... however blood sugar levels are worth keeping in check. How much you weigh is not the point; it's whether you're actually at risk of diabetes, liver, stroke or heart disease. Some very slim people can have really high blood sugar. If you are at risk then just start by eliminating as much added sugars as possible and having more fibre and healthy fats (not processed 'low' fat foods that are full of additives) - especially before the afternoon.

I personally can't get to sleep unless I've had some carbs (like sweet potatoes) in the evening and carbs are generally easier to digest, so I've split the day up according to what works for my digestive system and gives me some vitamins, minerals, omega fats and amino acids (protein).

I'm not a saint .. I still eat chocolate, because I basically need it - dark chocolate ice cream - a little goes a long way!

I can't see how dropping your levo would be helpful unless you currently feel overmedicated (and you should generally only reduce or increase by 25mcg at a time) - but you do need full thyroid blood tests: Free T4, free T3, TSH, antibodies (TPO and TG), plus ferritin, folate, B12 and D3.

Switching from levothyroxine to NDT (ThyroidS) had an almost immediate effect and I had soon shed the 4 stone I had gained on levothyroxine. I also went gluten free and I take 3000iu vitaminD and a multivitamin (immuneace) daily. In addition to the weight just falling off with no effort I generally felt much better especially psychologically - the awful depression that plagued me for years simply evaporated.

It must be the T3 in the dessicated thyroid and maybe T1, T2 and calcitonin do play a role. None of them are in levothyroxine. I had always been thin prior to overt hypothyroidism which in its very late and truly dreadful stages drove me to eat almost non stop yet I felt famished even after 3 or 4 full meals one after another. On Levo I simply could not shift an ounce and just got fatter and fatter without eating abnormally like before. I was very active running cycling and working outdoors in a physical job.

I imagine synthetic T3 would help in a similar way. If you can get it prescribed don't hesitate to give it a whirl

Thank you for all your interesting and varied replies - am off on holiday tomorrow with my mum and family but will get the tests when I get back and post here, Not expecting an instant result but glad to be on a path to somewhere!

Hello Im a 61 yr old female and have had thyroidectomy in 2000 ive been getting blood test about evry 3 or 4 mos since im on 175 mcg of thyroxine and have since been diagnosed with insulin resistance put on 1 Γ— daily on 1.8 of victoza inj. Daily now for 2 yrs its help stablize my weight but hard to loose . Slow but i also have very bad arthitis in my spine with spondylothisis and other issues with it so im in a lot of m pain hard to even walk with a walker let alone exerzie the ortho Dr wants me to loose 100 lbs then do a surgery putting screws and fusion on my back so im cinsidering weightloss surgery any suggestions for me ?

Hi usdebbie55, your post made me sad for you, how about making this reply of yours into a separate new post and asking for suggestions, I'm sure people will help.

If you have your thyroid test results with ranges then do make a new post as thyr01d suggests and people will reply with advice. It could be that your T3 is low in range and you are not converting the T4 well. Do you have Hashimotos ?

You may also like...