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Avatar universal

Thyroid medication and weight loss

Hello.  I was diagnosed with Hypothyroidism 2 years ago.  I have been put on the second lowest dose of synthroid (.5 milligrams).  I always had a problem losing weight, despite being athletic and eating healthy.  Now here I am almost 2 years later and down 15 pounds!  The weight loss came as a surprise to me.  So my question is:

Is it possible that after almost 2 years my metabolism is responding to the thyroid medication, causing me to lose weight?  I have always been active and cautious of what I ate, but could never drop the 10 pounds.  Now all of a sudden I keep dropping weight.  Could it be that my medicine is now working, causing my thyroid to function properly again?  


17 Responses
97953 tn?1440868992
It is possible that when you were hypothyroid your metabolic rate was lower than normal.  In normalizing the thyroid level with synthroid (unfortunately this does not cause the thyroid to function properly however) the metabolic rate increased back to an appropriate level.  So perhaps your difficulty with weight in the past was due to an underactive thyroid and now that it is corrected it is easier to lose weight.

It may have nothing to do with your thyroid - if the weight loss continues and is unintentional, see your doctor.
Avatar universal
I'd have to ask more questions...

were you overweight when you were diagnosed hypo? how much?
do you have Hashi's?  
Do you know what your Free levels are?

If you weren't overweight...and two years later started losing weight, that seems odd.  But it is true that it can take a while to start seeing weight loss after starting thyroid hormone.  

But usually...it's not dropping weight fast like you've described...unless someone has gone hyper on their meds.

So I would think if it's thyroid related, you could have Hashi's and perhaps have fluctuated out of a hypo mode, or gone into a hyper mode, or are overmedicated.  

But it does sound a little odd.
Avatar universal
Hello.  Thank you for responding.  I was not overweight to begin with, although I thought I was.  I am 5'7" and before being diagnosed with hypothyroidism I gained about 12 pounds(despite healthy eating and exercise) but returned back to my original 154 lbs.  Now I am at 140 lbs. 2 years later.  I am only 25 and like I said have been an athlete my entire life.  I exercise 4-5x a week and take eating healthy and being fit very seriously.  

I am only on the 2nd lowest dose of synthroid so I do not think I am highly medicated.  I only take that 6 days a week.  I was told I had Hashimoto's.  

So you think its odd that I could finally be losing weight from the diet and exercise?  If my metabolism is returning to normal, shouldnt exercise work for me like it would for other people trying to lose weight?  Also, I was told that once you have hypo it is irreversible.  You cant go from hypo to hyper.  But you can go from hyper to hypo.  

Thanks for your feedback
Avatar universal
In the early stages of Hashimoto's, it is quite possible to swing between hyper and hypo.  As more damage to the thyroid gland occurs, it is true that most folks end up permanently hypo...and irreversible.

Other folks who are hypo for reasons other than Hashimoto's could possibly reverse their hypothyroidism.  For example if they were eating a lot of soy products that were affecting their thyroid hormone production to the point of hypo, eliminating soy from the diet should reverse the condition.  

So since you are so young, I do think it might be prudent to check your Free T4 and Free T3 levels to assure your haven't swung out of hypo for a time or that you aren't in a hyper phase of Hashi's.

If you have swung out of a hypo phase of Hashi's, even a low dose of Synthroid could be too much.  That's why some folks have such a hard time with Hashi's...because it can fluctuate back and forth at times, until the permanent hypo is present.  

If those look good, then perhaps it is just your healthy diet and exercise.  

What I thought odd was that you were losing weight so fast.  If you don't have any other hyper symptoms like feeling hot, trembling hands, increased temperature, etc., then perhaps it is just fine.

Avatar universal
Hello again,

Well I just had my blood work done and I am still hypo.  My endocrinologist has kept me on the same meds for 2 years now.  The dosage hasnt changed.  Also, I have a lot of hypo symptoms, including a definite sensitivity to cold.  

So my hypo can turn to hyper and then back to hypo again?  I guess that worries me because I want to be able to maintain my current weight of 140 (which I was before I even had a thyroid condition). But if I happen to become hyper(and lose weight) and then go back to hypo again, would that mean Id put on weight again or have difficulty with losing weight?  I guess I didnt realize that with Hashimoto's you can fluctuate between hyper and hypo.
Avatar universal
It is true that it can fluctuate.  
But if your labs are still hypo after all this time, then I might be more inclined to think it was your diet/exercise that helped you lose weight.

But if you're still having symptoms of hypo, is your doctor addressing that?

Do you have recent Free T4 and Free T3 lab values?

Avatar universal
What does eating soy have to do with hypo or hyper? I saw you mention it and I eat it often so I am curious about your comment.
Avatar universal
Soy products can trigger thyroid disease or make an existing one worse. If you do a search "soy + thyroid" you can read more about it.  

Here's one statement:
"there is abundant evidence that some of the isoflavones found in soy, including genistein and equol, a metabolize of daidzen, demonstrate toxicity in estrogen sensitive tissues and in the thyroid. This is true for a number of species, including humans.

Additionally, isoflavones are inhibitors of the thyroid peroxidase which makes T3 and T4. Inhibition can be expected to generate thyroid abnormalities, including goiter and autoimmune thyroiditis. There exists a significant body of animal data that demonstrates goitrogenic and even carcinogenic effects of soy products. Moreover, there are significant reports of goitrogenic effects from soy consumption in human infants and adults."

Avatar universal
So is it bad if I am eating Luna Bars for Women?  I believe they contain soy. I also love Soy Crisps.  IS this going to do more damage with my hypothyroidism or what?  

A lot of health food I eat does contain soy ingredients.  Should I stop?

Avatar universal
that has to be your decision.
but based on the information about soy and its negative effects on the thyroid, I do not use soy products anymore.  The negative affects just outweight any possible benefit imo.
Avatar universal
Wow. I would never have known and I eat a lot of soy. Are there other foods bad for your thyoid? Guess i should investigate that more. Thanks
Avatar universal
Yes...cruciferous veggies aren't good for us.  They include broccoli, cauliflower, Brussels sprouts, cabbage, mustard, rutabagas, kohlrabi, and turnips.

If you search something like "goitrogens + thyroid" you should find some info on all this.
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