How To Lose Weight Rapidly If You Have Hypothyroidism

There are two things that about 80% of thyroid patients want: 

To lose weight and to lose it quickly. 

I totally understand the visceral need that many people have to get back to a normal weight but I would strongly caution against the rapid part. 

Rapid weight loss is almost always unhealthy, almost always leads to more thyroid problems (not less), and will almost always be short-lived. 

But that doesn’t mean that all weight loss treatments are created equal because that’s not true at all. 

So what I’ve done here is combine all of the most powerful and most effective weight loss treatments for thyroid patients so if you want to lose weight quickly (while doing it the right way), here’s what you should do:

#1. Prolonged fasting (1-4 days)

Fasting is probably the single most effective weight loss treatment that exists. 

Some people will say it’s really just a form of calorie restriction and there’s no difference between it and just cutting your calories every day. 

And here I will have to disagree. 

Fasting provides unique and specific benefits to thyroid patients that allow them to lose weight while avoiding the thyroid-related damage that can come with daily calorie restriction. 

We know from studies that this daily chronic starvation induces a change in thyroid function which lowers T3 and increases reverse T3 (1). 

This is probably the worst thing you can do if you have a thyroid problem because it takes your already low thyroid function and makes it worse. 

But fasting does not appear to cause the same negative thyroid changes. 

So it allows thyroid patients to safely cut their calories. 

The key here is making sure you do it correctly because it’s definitely possible to over fast and cause those same thyroid changes I just mentioned. 

Based on my experience, prolonged fasting in the range of 1-4 days every month is fine for the majority of thyroid patients. 

So if you’re serious about losing weight quickly, fasting should be first on your list of things to try. 

#2. Decreasing carbohydrates

I’m going to give an honorable mention here to cut your carbs with one big caveat: 

Just like daily calorie restriction, cutting your carbs long-term can definitely harm your thyroid. 

But I am going to give credit where credit is due by saying that cutting your carbs down for a short period of time or cycling your carb intake can provide a massive boost to your weight loss. 

Sure that weight loss is primarily going to just be water weight (2), but it can definitely act to slim you down if you only have a short period of time before something important like let’s say a wedding. 

But I do need to be clear here, the rapid weight loss associated with cutting carbs is mostly water weight, it doesn’t represent a loss in fat mass, and it’s short-lived. 

In other words, once you start eating carbs again, you’re going to regain that water weight. 

There is some benefit to this type of weight loss, though, especially if you can use it as a way to kick your butt in gear. 

Sometimes it’s really nice to see progress and if that change on the scale spurs you into action with more healthy eating and more exercise then I would say it is probably worth it. 

But just make sure you don’t say low carb for too long because that can decrease thyroid function (3). 

This is where carb cycling may make sense.

It can allow you to take advantage of this rapid weight loss without harming your thyroid in the process (4). 

On days that you do eat carbs, the magic number to shoot for is 100 grams per day for optimal thyroid health. 

#3. Zone-2 training

Exercise definitely plays a role in weight management, but the type of exercise matters.

Many people, experts included, will probably tell you that the best exercise for weight loss is high-intensity interval training. 

That would be things like tabatta, spin classes, sprints, the use of assault bikes, and so on. 

And while it’s definitely true that you will burn more calories in a shorter period of time, these usually aren’t the best options for thyroid patients. 

Studies have shown that really high levels of intensity have a negative impact on thyroid health (5), even for those with normal thyroid function. 

And this effect is exaggerated in people, like you, who have existing thyroid problems. 

This means there’s a sweet spot between no exercise and super high-intensity exercise and the sweet spot is zone 2 training. 

Zone 2 training is any workout that brings your heart rate to around 60% of your maximum (6) and keeps it there for a long period of time, usually around 30-40 minutes. 

This is a type of low-intensity workout that happens to be great for thyroid patients for a few reasons: 

1. The first, of course, is that it’s a more gentle way to workout that doesn’t put extra pressure on thyroid function. 
2. The second is that it causes less stress to the body which means it won’t spike cortisol in the same way that high intensity does.
3. The third is that it’s more sustainable long-term which means you’ll get better results.

How can you do it? Something simple like walking on a treadmill on an incline will do the trick, but you can get there doing lots of other things. 

If you don’t want to spend time calculating 60% of your maximal heart rate, you can estimate you are in zone 2 while working out because you should be able to have a casual conversation or sing a song to yourself. 

If you’re huffing and puffing while working out then you’re probably not in zone 2. 

#4. T3 thyroid medication

Out of all thyroid medications, T3 is by far the most powerful, it happens to also be the most difficult to get from your doctor. 

If you can get it, though, it has a much higher probability of helping you lose weight compared to T4-only medications like levothyroxine. 

You never want to abuse T3 to push yourself into a hyperthyroid state for weight loss like a bodybuilder might do. 

But it’s also perfectly safe to take physiologic doses of T3 which will, in turn, boost your metabolism. 

Doses of T3 in the 20-25 mcg range will do the trick. 

It’s enough to induce physiologic change in thyroid function, but not enough to put you at risk for serious conditions like bone loss or heart problems. 

As an alternative, if you are unable to get a prescription for T3 from your doctor you can also try taking T2. 

T2 is available over the counter and has shown promise in helping with weight loss much like T3. 

It’s not as powerful as T3, but it’s much easier to get because you can purchase it over the counter. 

#5. GLP-1 agonists

This is another name for the most popular class of weight loss medications and includes Wegovy and Ozempic. 

I’ve been pretty clear in the past that I do NOT recommend these medications for thyroid patients because of their many side effects but I can’t deny that they don’t work, because they do… really well, in fact. 

So why am I including it here? 

Because there’s one situation in which it may make sense to use them: 

If all else has failed and if your weight is causing a lot of psychological distress. 

Before you undergo any weight loss medication or treatment, you must always weigh the pros versus the cons. 

And I believe that, for most thyroid patients, the cons of these medications do not outweigh the pros. 

But you can make that decision on your own based on your circumstances. 

If you are someone who has tried everything else and nothing has worked, does it make sense to just lie down and accept your fate of being overweight forever? 

No way. 

We know that obesity is associated with a guaranteed risk of many diseases including cancer, so it may make sense in some situations to swap out that guaranteed risk of staying overweight for a potential risk of other problems caused by these medications. 

But don’t jump in without truly weighing the pros and cons and doing your own research because the side effects aren’t pretty (7). 

The most concerning of which, at least in my opinion, is that 20-50% of weight loss (8) associated with GLP-1 agonists comes from your muscles. 

It’s obviously up to you to decide what you want to do with your body but my recommendation would be to try everything else first before jumping into a GLP-1 agonist. 

These are probably the most powerful weight loss treatments that I know of for thyroid patients but don’t forget that good old-fashioned diet, exercise, and consistency will really get you the results you’re looking for. 

And if you need help with that, I’d recommend checking out this article next.