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Thyroid UK
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Hypo...but super thin???


When I was a kid I used to be thin but at the age of 12 I put on a lot of weight.

They found out that I was hypo so I started taking levo and I lost weight.

I took levo for more than 10 years and continued losing more and more weight. I started to have awful symptoms because of levo I guess (terrible joint pain).

2 years ago I started with NDT and I did great with that but I keep losing weight.

How can I be hypo??? Why is this? Maybe it has to be with the adrenals?

I know Hypos normally have the opposite problem. Any other having this problem?

I really need to put on some weight...I don´t look healthy at all.

11 Replies

Hypo means 'low' and we have low metabolism and that may be the first symptom (unexplained weight gain) people become aware of. As the dose of thyroid hormones are increased metabolism is raised and weight is reduced. Sometimes doctors stop increasing dose when TSH reaches somewhere int he range and the patient may not reach an optimum doseL and gain unwanted weight and have to diet. Levothroxine may not convert to sufficient T3.

Your lost weight may be because you have hormones T4, T3, T2, T1 and calciton in NDT. If you are losing too much weight (I am not medically qualified) is reduce your dose slightly every six weeks to see if your weight stabilises.

Hypo doesn't mean weight gain. I never gained . Hypo means slow and our body's metabolism slows down, low pulse and low temp usually.

Are you consuming enough calories daily and have a good diet.


Yes I eat quite a lot actually.

I am sure that I dont have to lower the dose. Actually I may have to increase it. I just take half pill of Naturethroid 3/4. Its such a small dose.

And before that I had been more than 10 years taking levo 75mg. May I have nutrient malabsorbation?



You could be losing weight because of low stomach acid, meaning that you can't absorb nutrients. It would be a good idea to have your vit D, vit B12, folate and ferritin tested.

Not all hypos gain weight. Some stay the same weight, some lose weight. Losing weight does not disqualify you from being hypo. There are over 300 symptoms of low T3, but you don't have to have them all. :)

1 like

Although it's more usual to gain weight when hypo there's a small percentage of people who really struggle to maintain weight

You may be coeliac or gluten intolerant. Gut issues and food intolerances are more common when hypothyroid especially if you have autoimmune thyroid disease, diagnosed by high thyroid antibodies. (Hashimoto's)

Or as Greygoose says, low stomach acid is more common problem when hypo. Then struggle to absorb nutrients

We are not what we eat, but what our gut absorbs. Malabsorption is more common when hypo

Have you had vitamin D, folate, ferritin and B12 tested?

Do you have any gut symptoms or issues.

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I have hashimotos and I'm a Coeliac. At one point I was super skinny (I went down to a size 4) and was always told by the doctors that my problems were due to me not eating. I ate like there was no tomorrow. Ask to be checked for coeliacs. Its common to have more than one autoimmue disease. Going gluten free is not as hard as you think.


What do you do when you really crave bread? I avoid 'gluten-free bread' in the freezer section as I've read it is not that healthy and sometimes use ingredients like tapioca, rice flour and foods that may 'cross-react- like gluten. I also want to keep sodium as low as possible. I used ezekiel low sodium sprouted grain bread for a long time but understand it has a small amt of gluten.Aside from the occasional 'bread-thing' you're right. Gluten-free is not that hard. Is there a healthy substitute I can easily make at home? It doesn't have to be 'true (risen) bread.' Flatbread or crackers will do. irina


Have your cortisol levels been checked by your doctor? Low cortisol can look like this.


Hi, thank you for answering.

I have never had any stomach issues. And I eat quite a lot. I have good appetite. But Its like impossible for me to gain weight.

I never checked ferritin, folate, D3,B12, and cortisol.

Maybe you are right and I am not absorbing the nutrients of the food. How can I know that? And if so, what could be done?

Also, I didnt know that low cortisol could be the reason.


1 like

For full Thyroid evaluation you need TSH, FT4, TT4, FT3 plus TPO and TG thyroid antibodies. Plus vitamin D, folate, ferritin and B12.

Essential to test thyroid antibodies, FT3 and FT4, plus vitamins

If you are in the U.K.

Private tests are available. Thousands on here forced to do this as NHS often refuses to test FT3 or antibodies


Medichecks Thyroid plus ultra vitamin or Blue Horizon Thyroid plus eleven are the most popular choice. DIY finger prick test or option to pay extra for private blood draw. Both companies often have money off offers.

All thyroid tests should ideally be done as early as possible in morning and fasting.

If on Levothyroxine, don't take in the 24 hours prior to test, and if on T3 don't take in 12 hours prior to test, delay and take straight after

This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip, GP will be unaware)

If antibodies are high this is Hashimoto's, (also known by medics here in UK more commonly as autoimmune thyroid disease).

About 90% of all hypothyroidism in Uk is due to Hashimoto's. Low vitamins are especially common with Hashimoto's. Food intolerances too, especially gluten. So it's important to get tested.


Hi Josu. I believe you are 26, male, and from Spain? I think I saw that you wrote that you’ve been on levothyroxine 75 mcg since you were 12? Your weight loss and aching bones are quite curious. I believe you need a through work up from a good doctor, including some extensive blood tests to look at your status. Have you been tested for Hashimoto’s as your cause for hypothyroidism, or tested for other autoimmune diseases?

For blood work, aside from a complete thyroid panel, a comprehensive metabolic panel, a complete blood count, you will need to find out your complete iron status. This is done by conducting an iron panel, not just testing ferritin. Ferritin by itself is incomplete info. Also test your vitamin D and B12.

Have you had any broken bones, stiff joints, joint swelling or bony enlargements around joints? What other symptoms do you have? Depending on your answer, there are a few other blood tests to add to the list to eliminate or confirm some conditions, and lead you down the path of figuring out what is causing your symptoms.


Yes, you should work on eliminating other possible causes before changing your thyroid dose. There are labs that can do a gut health panel, and you should make sure your doctor is thinking about your uncontrolled weight loss as possibly arising from something beyond the thyroid. Good advice from Shootingstars above.


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