Thyroid UK
88,782 members103,366 posts

I have underactive thyroid and am skinny and underweight, why is this and how do I gain weight?

I am in my late teens and have underactive thyroid, and I am very skinny and underweight. This is most unusual for people with underactive thyroid, can anyone tell me why this is and what I can do to gain weight and maintain my health?

19 Replies
oldestnewest

Hi I am too. My Endo always says that some times the symptoms for Hypo are the same as Hyper. Make sure you have had recent bloods, TSH, T4 and Free T3. It is just possible that your FT3 is too high. If too low it causes weight gain.Make sure you are not diabetic. If seeing an Endo or even a GP should have tested for this, Glucose and the better Hb Aic tests I would find a good Endo and then ask for a referral. It is possible that Adrenal and Parathyroid ( PTH) may be desirable, they would certainly know this. My Hepatologist ( liver) says that it is important, in spite of major medical conditions that I should have, high fat food eg butter etc and lots of milk ,full cream etc.This is in spite of my major medical conditions to the contrary.

If not seeing an Endo this is important but must be good. Of all consultants they have the widest knowledge of all the body and how it works.There may be something that they think needs testing.etc. They are also normally motility experts.

I am sure it is tough for you but at least by not being over weight you and your organs are healthy.

Best wishes,

Jackie

Not sure if you know but if you wish to reply to some one, click on "Reply to this" under the post. Sure you do , given your age, my 13 year old grand daughter is brilliant on a computer!

Reply

Thank you very much for your reply. I was diagnosed about 2 months ago, and am on 50mg. My blood tests after one month of taking the medicine showed that my thyroid levels are now normal and not underactive, so my GP did not increase my dosage. Just puzzles me as to why I am so skinny though. I will definitely take your advice and see an endo, he will probably be able to give me some answers. Thank you for the help Jackie :)

Reply

Hi,Jackie maybe ur taking the wrong medicine..I take (armo thyroid) which a lot of people haven't heard of I have no side effects! I as well have it low I'm 5' and weigh 125 and I'm a size 5 I hope that I was helpful in your journey..Lisa

Reply

If your hypothyroidism is not being optimally treated, this might be the cause. What dose of thyroxine are you taking and what were your most recent thyroid test results?

Reply

Hi, I was diagnosed 2 months ago and am on 50mg. One month after being diagnosed my blood test results showed that my thyroid levels are now normal....

Reply

This suggests that you may not yet be on the right amount of thyroxine. 50 mcg is a relatively low dose of levothyroxine and most (but not all) people do end up on a higher dose than this before their symptoms resolve.

Blood levels being 'normal' is not an acceptable answer when treating thyroid hormone deficiency. Your GP should be aiming to bring your TSH down below two. Many people don't feel well until their TSH is at one or below.

Please contact your surgery to obtain the actual thyroid test result numbers. Ideally, find out what the numbers were at the point of diagnosis, and at the most recent test since being on medication, then come back and tell us so that we have a clearer picture of your situation.

Reply

Thank you for this information. I will call up the surgery tomorrow and find out my exact results, and see what they say and get back to you. I was also on antidepressants for a short period, less than a month, until I convinced myself that it was just not the thing for me and their had to be another reason for my depression, and then started taking levothyroxine.

Reply

Hi, I called up the surgery to get my exact results, and they are not willing to give me my TSH levels at the point of diagnosis, but my TSH after one month of medication (50 mg) was 1.07 . Does that sound alright? Shall I ask them to increase my dosage or look into it further? Advice would be much appreciated !

Reply

Not everyone puts on weight. I only put on 4kg at my worst which was in the few months before treatment. Specialists have told me I'm fine because I 'look fine'.

Reply

Hi, I echo the comments above, I'm underweight too. I probably don't eat loads but I eat whatever I want, including snacks and never miss a meal. I find it a bit embarrassing as I'm sure some people think I've got a problem with food, which I don't at all. My thyroid is under active and I'm on thyroxine, and at the moment my adrenal glands aren't working too well. Altho weight gain is a more typical symptom it seems that the opposite can be true too. As someone said above you should get any medical causes checked, but other than that, does it bother you?

Reply

Hi, yes I am exactly the same towards food. I plan to see someone and explain the situation, asking if they have an knowledge as to what the problem could be. I'm happy for what I am and I'm not majorly bothered, I'd prefer being this weight rather than being overweight, but it would be nice to find out the problem and become a bit more healthy.

Reply

My daughter lost an enormous amount of weight and weight loss isn't often recorded in books on the thyroid or on the internet.

It can sometimes be linked with the adrenals. My daughter took thyroxine, but was later changed to Armour thyroid and once she was well, her weight increased to a very normal weight for her height.

Reply

Thank you for the information. Yes I'm on levothyroxine at the moment aswell.

Reply

Like I told the other ladies or girls I'm taking armo thryroid and its works really good...not many doctors know bout this medicine.. Good luck

Reply

I too lost a lot of weight when I was first diagnosed - went from a size 10 to a size 6-8. Then they stuck me on levothyroxine and am now unhappy and 2 stone overweight.

I am in a battle with my GP at the moment about my meds, I do hope you get your meds sorted soon and hope you have a sympathetic GP. I say keep hassling and you'll get there x

Reply

Thank you for the information. I am currently on levothyroxine, I shall speak to my GP about it and see what he says. haha good luck with that, hope everything works out :)

Reply

Well, actually with low thyroid you may not be that hungry. It also deals with protein metabolism and muscle breakdown. You may be skinny with zero muscles with low thyroid. Why on earth would someone replace their thyroid with t4 only medications? Dessicated thyroid closely resembles your thyroid with t4 and t3 as well as t1 and t2. I would go by body temperature and pulse rate not tsh.

Reply

If adrenals are not in good state which is common with thyroid issues then T3 and armour can put a huge stress on them. so make sure skinnyness isnt due to adrenals before trying armour or T3,

Patchy

1 like
Reply

Hi.. I too have underactive thyroid.. I am 24yrs old, I am a mother of 3 and I weigh 105lbs. It's really hard to put on the weight and keep it on. I try to exercise to make muscle but I struggle with that too. But I don't really know why. My specialist finds it odd. I'm the first case she's ever seen with hypothyroid and be really petite

Reply

You may also like...