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Thyroid UK
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Why am I so skinny

Hi I'm new to this so forgive me for any mistakes I will make. I'm a 25 Yr old F, 5'2 and only 97 LBS!!! No matter what I do I CANNOT gain a single pound!! I was diagnosed with a "severely" under activate thyroid ( Hypo) about two years ago. And supposedly 25mcg has evened me out since then with no need for adjustment. HOWEVER about a year before diagnosis I lost a EXTRAORDINARY amount of weight in a matter of weeks. I went from a healthy weight of 115 lbs down to 95 lbs. Went through many tests to find anything causing the issue. Tested for worms, thyroid issues, infection, STDs! THE WORKS!!! NOTHING FOUND! I tried a crazy diet of high protein and low sugar! Body building shakes and exercise ect. Doctor was stumped and so am I. If anyone has experienced anything like this or knows what could be causing this I would be very grateful for any help! TIA

11 Replies

That's not really skinny, I was the same as you at your age. it was considered normal/desirable 40 years ago (think Twiggy), but the general population has got fatter since. Hey, a size 10 was a 22 inch waist back in those days. The only way to gain healthy weight is to gain muscle mass and get enough rest - a bodybuilding gym not more than 3 times a week. However you might have Autoimmune thyroiditis (Hashis) which meant you had an overactive phase just before you were diagnosed. Do you have current TSH, Free t4, Free T3 and B12, folate and ferritin results? B12 can help to improve appetite. I remember being told by my doctor to eat cake and drink stout (I got Mackeson on prescription!). It made no difference at all. The more you worry about it, the more you'll burn up calories.

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Yes I agree worrying is bad : (

I should have my lab results today and will post them ASAP.

My appetite it fantastic I eat A LOT!! I just want to feel like me again and with all the symptoms I have every day it's hard to stay positive especially when I look in the mirror and see my body the way it was when I was 12. I used to be a healthy weight and feel good and now I'm skinny and feel horrible. I get migraines nearly 4 days a week. Heart palpitations daily. Cold sweats daily, hot flashes daily, very low body temp, nausea, random pains all over and also have anxiety and anxiety attacks.



I was advised to eat frequent small meals to maintain weight and hopefully gain. Protein shakes in milk inbetween meals helped me gain some weight.

If you post your recent thyroid results and ranges I will advise whether you are optimally dosed on 25mcg.


Thank you Clutter, I will have my labs back today and will post them ASAP. And yes I went through about a two months of eating around six meals a day and in between drinking protein shakes and other high protein snacks. I was logging all my calories in a journal and trying to consume about 8,000 calories each day! With no luck of course other than a very sick stomach and lots of poo lol. I can't even begin to describe how hard it is to eat 8,000 calories worth of food in one day.



I can imagine. Must have felt like you were being force fed. I substituted soup for tea, coffee and soft drinks at one time in an attempt to get in more calories.

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


Ok thank you so much!


25mcg is only half the standard starter dose. Most patients end up on around 100-200mcg Levothyroxine

Bloods should be retested after 6-8 weeks and dose increased in 25mcg steps until TSH is around one and FT4 towards top of range and FT3 at least half way in range. Retesting after each increase

If you are under medicated then vitamin levels will be terrible and gut function severely affected

Ask GP for coeliac blood test and to test vitamin D, folate, ferritin and. b12

Post results and ranges when you get them

Hashimoto's affects the gut and leads to low stomach acid and then low vitamin levels

Low vitamin levels affect Thyroid hormone working

Poor gut function can lead leaky gut (literally holes in gut wall) this can cause food intolerances. Most common by far is gluten

According to Izabella Wentz the Thyroid Pharmacist approx 5% with Hashimoto's are coeliac, but over 80% find gluten free diet helps significantly. Either due to direct gluten intolerance (no test available) or due to leaky gut and gluten causing molecular mimicry (see Amy Myers link)

But don't be surprised that GP or endo never mention gut, gluten or low vitamins. Hashimoto's is very poorly understood

Changing to a strictly gluten free diet may help reduce symptoms, help gut heal and slowly lower TPO antibodies

Ask GP for coeliac blood test first.









Thank you! I have had my levels tested every 3 months. Always told they are within the "normal" ranges. I don't know much about my condition, I have done a lot of research but it's so complex I'm still learning and trying to better understand how this stuff works lol. I will talk to my doctor about the suggestions you made and I will definitely be reading the links as well. : )


Coeliac and gluten intolerance are both often responsible for poor nutrient absorption

Highly recommend Dr Chatergees new book

The four pillar plan


A good friend lost a lot of weight & couldn't gain it back until she gave up gluten. She was finally tested for celiac disease & was positive. Worth it to give up gluten to see if it helps. Gluten's in cosmetics & personal care products, so only use & eat things labeled gluten free.

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I was like you my whole life, and still underweight. This is why my hypo was not picked up. I completely understand - it’s so hard to put weight on and it made me miserable as a teenager. Going gluten free has helped me a little. Post your results as soon as you can and the lovely admins will check for you. X

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