Losing Weight on Levothyroxine - Why it’s Not Working

Losing Weight on Levothyroxine (Why It’s Not Working)

Will Levothyroxine Actually Help you Lose Weight? 

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Here’s the problem:

Is it well known that patients with hypothyroidism (low thyroid function) have problems with weight gain. 

Weight gain is probably the most common and most frustrating symptom associated with low thyroid function, Hashimoto’s thyroiditis, hypothyroidism, thyroidectomy, and RAI

There is no disputing the fact that low thyroid LEADS to weight gain

So it makes sense that once you TREAT your low thyroid that this weight should come off, right?

Doesn’t it make sense that once you CORRECT the low thyroid problem with a prescription medication like levothyroxine, that your weight should normalize and you should be back to normal?

You would think so, but it doesn’t actually happen in common practice. 

And if you ask your doctor about why this is the case they will handwave you off by saying something about how much you are eating, that you aren’t exercising enough, or that it’s related to your age. 

So what gives?

It turns out that while levothyroxine is certainly NOT a weight loss medication (by any stretch of the imagination), it can potentially help you lose weight but only if it is used correctly. 

This is what we are going to talk about today…

  • Why thyroid patients taking levothyroxine don’t lose weight
  • Other options available to you as a thyroid medication
  • Why some thyroid medications are better at helping with weight loss compared to others
  • Who actually does well on T4 only thyroid medications like levothyroxine

Let’s jump in: 


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Reasons Levothyroxine is Not Helping You Lose Weight

I’ve had the opportunity to treat hundreds of thyroid patients when I was practicing and I can tell you from personal experience that levothyroxine really just doesn’t work that well at helping shed extra body fat. 

It’s not that it CAN’T work, it’s just that it’s often used incorrectly, it’s underdosed, and/or thyroid patients aren’t sure what to expect when using it. 

So while levothyroxine certainly isn’t the best thyroid medication around (we will talk about some better alternatives later), it is still definitely an option that can be used to help rev up your metabolism and help your body get into weight loss mode. 

But you should be aware of some of the potential issues that you might run into when using it. 

Below you will find 4 important questions that you should be asking yourself if you are taking levothyroxine and not losing weight. 

As you read these questions keep track of your answers. 

The answers to these questions will help you figure out why levothyroxine is not helping you lose weight

#1. Have You Waited Long Enough? (Are you Being Impatient?)

This is something that is really important for thyroid patients to understand. 

Whenever you do anything designed to target the thyroid, you must wait a sufficient amount of time before declaring that that thing either worked or not. 

It takes a long time for therapies to take effect and to impact your thyroid. 

How long?

About 4-6 weeks. 

This means that if you make any change to your thyroid medication dose (OR changes to your thyroid supplements!) you won’t see any changes manifest in your body for around 4 to 6 weeks. 

Imagine that you’ve felt poorly for the last 6 months and you finally get put on thyroid medication. 

And after taking your levothyroxine faithfully for 10-14 days you are wondering why you aren’t losing weight and why you aren’t feeling better yet. 

This is why. 

And to complicate matters further, you have to realize that most people don’t get put on the right dose of thyroid medication the first time. 

When you start on levothyroxine you are just given a basic starting dose. 

This dose may be too high or it may be too low (which is more common) but you won’t know for 4-6 weeks. 

It will then take at least another 3-4 rounds of adjusting your dose before you get on the right dose. 

That means it can take up to 12 weeks (at the soonest) to 24 weeks (usually at the longest) to find your dose. 

You get this value by multiplying 3-4x (the number of rounds of adjustments that will be made to your levothyroxine) by 4-6 weeks (which is the number of weeks it will take for you to notice a difference). 

Before you do anything else make sure you have given your levothyroxine enough time to take effect! 

#2. Is it Getting Into Your System? (Is it Being Absorbed?)

The next question you have to ask yourself is whether or not your levothyroxine is actually getting into your system. 

In other words, is the thyroid medication you are taking by mouth actually getting into your bloodstream through your intestinal tract?

It may sound obvious because we just assume that any medication we put into our mouths must be absorbed, right?

Well, you’d be wrong in the case of levothyroxine and other thyroid medications. 

Levothyroxine, in particular, is quite finicky and will look for virtually any excuse to not be absorbed correctly (1). 

Did you take your levothyroxine with food? It won’t be absorbed well. 

Did you take your levothyroxine with coffee in the morning? It won’t be absorbed very well (2). 

Did you take your levothyroxine at the same time as other supplements or medications? It won’t be absorbed very well if you did. 

And if your levothyroxine isn’t making its way into your bloodstream then how will it work?

It won’t. 

Which makes absorption a key issue when considering whether or not your thyroid medication is working. 

Thyroid patients are also notorious for having additional intestinal issues which can further complicate absorption of thyroid medication. 

Conditions such as irritable bowel syndrome, gluten intolerance, SIBO/SIFO (3), and acid reflux can all interfere with the absorption of levothyroxine. 

It could very well be that levothyroxine is the right medication for you and that you are taking the right dose but it can’t get into your body because of your gut. 

It should go without saying but if you don’t get levothyroxine into your bloodstream then it won’t help you lose weight. 

#3. Are You Taking Enough? (Is your Dose Sufficient?)

The next thing you need to think about is your dose. 

And by dose, I am referring to how much you are taking. 

We kind of touched on this in #1 but it’s worth going over here as well. 

The unfortunate truth is that a great many thyroid patients are taking the right type of medication for their body only they are on a dose that is too small. 

In other words, they are being underdosed. 

This is actually quite common. 

And the reason is simple. 

Your doctor would prefer that you be underdosed as opposed to overdosed. 

So doctors frequently err on the side of giving you too little levothyroxine. 

In addition, there’s a good chance that your doctor is not giving you enough thyroid medication if they are using the TSH (thyroid-stimulating hormone) as a guide

The TSH is one of the worst ways to measure thyroid function in the body because your free thyroid hormones (free T3 and free T4) are much more important. 

It could very well be that your dose of levothyroxine just isn’t quite high enough. 

If your dose is too low it will be very hard for you to lose weight. 

#4. Is it The Right Medication For Your Body? (Would Another Thyroid Medication Be Better for you?)

Lastly, and if all other options have failed, it may simply be that levothyroxine is just not the right thyroid medication for you. 

There are at least 8+ different types of thyroid medications and yet doctors consistently prescribe only one or two. 

They love levothyroxine and Synthroid but fail to prescribe any of the other versions of thyroid medications even though they are viable and effective options. 

If you’ve never heard of these thyroid medications then I would recommend that you spend some time familiarizing yourself with them!

Please see this list below:

These are just a handful of alternatives available to thyroid patients and they can all be used if you are not doing well on levothyroxine/Synthroid

Switching between thyroid medications is not very difficult but it may require some time and energy to figure out what works for you. 

But the result will be worth it if it means more weight loss! 

The Best Thyroid Medication For Weight Loss? (T4 vs T3)

Is there a single best thyroid medication for weight loss?

Not really. 

The best thyroid medication is the one that works for you. 

I’ve seen people lose weight on virtually all types of thyroid medications ranging from levothyroxine to Cytomel to Armour thyroid and everything in between. 

The key to losing weight on thyroid medication is finding what works for YOUR body. 

Whatever thyroid medication you are taking MUST be getting absorbed and utilized by your body (and converted if your thyroid medication contains only T4), it must be at the right dose, and you must ensure that you’ve given it enough time to really kick in. 

Having said that, I want to point from my own experience that any thyroid medication which contains T3 is typically more effective than those that only contain T4. 

Levothyroxine and Synthroid both only contain T4 thyroid hormone so they don’t often work as well as other medications that contain T3 thyroid hormone such as Cytomel and liothyronine. 

T3 thyroid hormone is usually far more effective than T4 only thyroid medications because it is already activated. 

T4 medications such as levothyroxine and Synthroid require an extra step before your body can actually use them. 

This step is known as thyroid conversion and it is a step that a lot of people have issues with. 

If your body doesn’t convert your medication into T3 then your body won’t be able to properly utilize it. 

If you bypass this conversion process with a more powerful thyroid medication (such as T3 thyroid hormone) then your thyroid medication is ready to be used by the body quicker. 

Who Does Best on T4 Thyroid Medication? 

Does this mean you have to take T3 thyroid medication if you want to lose weight?

Not at all!

There are still plenty of people who do well on levothyroxine and Synthroid and who can lose weight on these medications. 

There are also plenty of people who don’t but let’s focus on those who do for a moment. 

The following is a list of people who are MORE likely to do well on levothyroxine. 

Those who are:

  • Treatment naive – If you’ve never used thyroid medication before at all then starting with levothyroxine is a great idea. It is much more gentle and milder compared to other thyroid medications. 
  • Sensitive to T3 thyroid medication or NDT thyroid medication – Some people can’t tolerate even a small amount of T3 thyroid hormone. If you are one of those people then T4 thyroid medication like levothyroxine may be your best bet. 
  • Sensitive to medications and supplements in general – If you are someone who is sensitive to pretty much all medications and supplements then starting with levothyroxine is usually your best bet. 
  • Suffer from minimal chronic illness – In general, the more chronic illnesses that you have the more aggressive you will need to be with your thyroid medication. If you don’t have any other chronic illnesses (such as high blood pressure, high cholesterol, obesity, diabetes, etc.) then levothyroxine is more likely to work. Those who do have these chronic illnesses tend to do better on T3. 
  • Seeing improvement on levothyroxine in a short period of time – If you’ve been taking levothyroxine for a short period of time (on the order of 2-4 weeks) and you are seeing improvement already then that is a very good sign that this medication will work for you. 

Wrapping It Up

Is it possible to lose weight on levothyroxine? Absolutely. 

Is it easy to lose weight on levothyroxine? Not exactly. 

Is levothyroxine the best thyroid medication for weight loss? No. 

Will it help YOU lose weight? That remains to be seen!

If you are someone who is struggling to lose weight DESPITE taking levothyroxine faithfully then make sure you check out the first section which describes 4 reasons why it may not be working. 

If you’ve gone through all 4 of those areas and you are still having issues then you may need to consider swapping over to a different thyroid medication. 

Before we close I want you to remember one very important thing:

As a thyroid patient, you do NOT have to suffer from obesity and weight loss resistance. 

There is a way for you to lose weight and keep it off but it may require effort on your part. 

Use the tools on my website to help you get there!

Now I want to hear from you:

Are you currently using levothyroxine?

Are you having issues losing weight?

Do you feel that levothyroxine is helping with your weight loss efforts? Why or why not?

Have you tried any other thyroid medications? Were they more effective than levothyroxine for YOU?

Leave your questions or comments below! 

#1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6209618/

#2. https://pubmed.ncbi.nlm.nih.gov/18341376/

#3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4056127/

how to lose weight on levothyroxine

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About Dr. Westin Childs

Hey! I'm Westin Childs D.O. (former Osteopathic Physician). I don't practice medicine anymore and instead specialize in helping people like YOU who have thyroid problems, hormone imbalances, and weight loss resistance. I love to write and share what I've learned over the years. I also happen to formulate the best supplements on the market (well, at least in my opinion!) and I'm proud to say that over 80,000+ people have used them over the last 7 years. You can read more about my own personal health journey and why I am so passionate about what I do.

P.S. Here are 4 ways you can get more help right now:

#1. Get my free thyroid downloads, resources, and PDFs here.

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#4. Follow me on Youtube, Facebook, TikTok, and Instagram for up-to-date thyroid tips, tricks, videos, and more.

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