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Thyroid UK
93,372 members107,420 posts

On levothyroxine but gaining weight

Hi everyone

I'm relatively new to this site but I'm so glad I found it. I've been looking through the posts & I think the support you get it is just brilliant.

Basically, I was diagnosed with an underactive thyroid in April 2016. I was told I was borderline with a TSH of 5.1 so was started on 25mg of levothyroxine. It since increased to 100mg. A recent blood test came back with a tsh of 3.1.

The problem I'm having is my weight is creeping up. I have very little carbs in my diet & try to eat as healthy as I can. I have porridge for breakfast most mornings & all bran for lunch. I do have a very bad sweet tooth which I'm trying my hardest to control.

I recently invested in Gaia herbs thyroid support after reading brilliant reviews but I'm at a loss as to why my weight is increasing.. Every few days, it's goes up a pound. I'm too scared of weighing myself now & feel so depressed. I have 3 young children under the age of 4 to look after too & don't want to be feeling like this. I must admit I am feeling much better now that I am on 100mg levothyroxine.

Can anyone help me pls.

I recently give blood to have my vit D, B12, ferritin tested so should have results Wednesday - Thursday

2 Replies


You are a little undermedicated. The goal of Levothyroxine is to restore the patient to euthyroid status and for most people this will be when TSH is 1.0, or lower, with FT4 in the upper range. Read Treatment Options in thyroiduk.org.uk/tuk/about_... Email louise.warvill@thyroiduk.org.uk if you would like a copy of the Pulse article to show your GP.

Post your new blood results and ranges in a new question and members will comment.


how is your free t3...is it at the top end of normal..that is your metabolism hormone and the same thing happened to me and drs ignored it.....i gained 30 lbs and my tsh was always around 1 so.......i have started nature throid...which has t3 in it..to help and i can see a decrease in water weight slightly already....in a couple months....MANY PEOPLE DONT CONVERT T4 WELL SO THEY END UP WITH LOW NORMAL FT3 AND GAIN WEIGHT...my new dr agrees


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