Thyroid UK
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Weight gain

Hi! Im 37, I have been living with my Dx since 2010. I recently was underactive thyroid again, and increased dose from 75mcg to. Ow 100mcg of Levothyroxine. I gained weight due to hypothyrois for the first time this year, 10lbs. I am a very active mom, my life busy all day but I also exercise 3-5 times a week. Some of those workouts are runs and some arenintense interval training- which is great exercise! I haven't been able to lose a single pound!!! I eat generally healthy, no junk food all homemade foods, no frozen or boxed meals, except the weekend cheat meal. Ive been actively working on losing weight since August and not one pound!! So frustrated!

11 Replies

Do you have your latest:

1. TSH

2. FT4

3. FT3

blood test results?

You should be able to get TSH And FT4 at least from your doctor. Go to reception and ask for a copy of your latest blood test results with ranges. It is your right under the Data Protection Act 1998. It should take 3-5 working days for you to get them as the receptionist will have to get consent from the doctor.

Once you have them post again.

The reason why these are needed is that unless they are optimum you will not lose weight and in fact intense exercise - the interval training - while they are not optimum is actually harming you.


Hi! My last TSH WAS 3.48 tested October 2016, and I haven't been tested on the FT4 or FT3 except in August 2016 my FT4 was 1.1....but since August I havent had a FT4 test. I just had my TSH its at 1.58 results today.


Standard NHS thinking I'm afraid as they go by TSH alone.

Unfortunately only if you do private testing will you know your levels if your GP is too thick to test them.

I suggest you read thyroid the charity who run this forum's website to get more clued up even though you have been given good info by greygoose

1 like

I very much appreciate your help! I am very clueless, I figured doctors know best but now I am understanding that there are things that definitely so not make sense ! I will research some more here!! Thx!


General rule if it's an emergency hospital doctors will know what to do to keep you alive, but if it's a chronic condition then they, whether hospital doctor or GP, won't necessarily know how to treat you to live a normal life.

So if you or anyone in your family feels unwell and you are sure there is a problem don't leave it. Do your research including asking people you know who have proved they have commonsense, and see someone different in primary care.

BTW This is one reason is why A&E attendences are higher than they should be.

1 like

Well, that's probably where you're going wrong. If your FT3 isn't optimal, all attempts to lose weight will probably end up with you putting on weight.

Low-calorie diets have a negative effect on conversion of T4 to T3. Low T3 causes symptoms. Weight gain is a hypo symptom.

Strenuous exercise, not only uses up the calories that you need for conversion, but it also uses up your T3, which you cannot easily replace. Therefore, you make yourself more hypo, and put on more weight.

The first thing you need is to see your blood test results, as bluebug says. You need to see exactly what was tested, and exactly what the results were. Even if you can only get TSH and FT4, if the FT4 is low, then you're not on the right dose, yet.

If the FT4 is up the top of the range, then you need to get your FT4 and FT3 tested at the same time, to see how well you are converting.

But, until you have all that vital information, I would give up the running, etc, if I were you. Just gentle walking, swimming and yoga, until your T3 is optimised. You might even find you lose weight if you do that! :)



I really like your posts, as you seem very knowledgeable about thyroid disease and treatment.

In your opinion, what are optimal FT3 levels?! I have seen so many conflicting advice it feels like my head is spinning...some say if you are on NDT, or a combination of synthetic T4 and T3, or synthetic T3 only, your FT3 levels should be midrange or slightly below if you go to the lab 12-24 hours after taking it because, if they are at the top of range at that time, that means you are overmedicated and should cut back (on T3, that is). Others claim you should go to the lab 1-2 hours after taking your thyroid meds, as you will then know how much T3 you have in your system on the day you take your meds...which could prove more or less complicated depending on whether you take your meds once or twice daily, or even several times daily...

I'd appreciate any input on this (from you or anyone else), as I am beginning to feel that my lab results have very little to do with how I am actually feeling...yet, doctors only seem to care about lab results...:-(


I don't have any opinions on optimal blood tests. Optimal is how you feel, not what it says on a lab sheet. If your FT3 is at the top of the range, but you're still very hypo, then it's not optimal, is it. Unfortunately, doctors - never having any practical experience of being hypo (for the most part) - have no idea that it is possible to still be hypo with FT3 at the top of the range.

Blood tests are just a guide. If you feel bad and your FT3 is way over-range, the logical thing to say is, well, perhaps you're over-medicated, try reducing your dose. But, there will be some people who feel great with their FT3 over-range, and reducing their dose will make them feel ill.

Thyroid is not an exact science, despite what doctors think. It's more of an art to get the dose just right, no matter what the blood test says. It's all trial and error.

As to the time to leave between the last dose and the test... that's more difficult. If you leave it too long, you're going to get a false low, and could increase the dose by too much. If you don't leave it long enough, you'll get a false high, and might decrease your dose when it's not necessary. But, the last person I would ask for advise on that subject, is a doctor! I've always read that 12 hours is about the right length of time, and I've always gone with that. But, I would in no way stake my life on it! lol


Thanks a lot! I have always waited 24 h before going to the lab but maybe I shouldn't...that's food for thought, thanks!




The only tests were for T4Free 1.1 this was my August 2016 results, and October 2016 they only tested TSH 3.28.


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