Why Endurance Athletes Without a Thyroid Often Struggle with Weight and Energy

One of the most frustrating things many people experience after losing their thyroid is the feeling that their body suddenly works differently.

Energy feels unpredictable.
Weight becomes harder to manage.
Training doesn’t always respond the way it used to.

And for endurance athletes, that can feel incredibly confusing.

If you’re running, cycling, swimming, or training for long events, you would assume the miles alone would keep weight and energy balanced.

But when you don’t have a thyroid, things can work a little differently.

I’ve lived without a thyroid since 2005, and over the years I’ve learned that endurance training with thyroid hormone replacement requires a little more awareness and patience.

The thyroid gland normally helps regulate metabolism, energy production, and how the body uses fuel. When it’s removed, those hormones are replaced with medication such as T3 and T4.

Those medications are incredibly helpful, but they don’t always mimic the body’s natural rhythm perfectly. Some days energy feels great. Other days it feels like the tank is running low.

For endurance athletes, that matters.

Long workouts require steady fuel, efficient metabolism, and recovery that allows the body to adapt to training.

Without a thyroid, three common challenges often show up.

1. Energy Can Fluctuate More Than Expected

Some days training feels fantastic. Other days even an easy run can feel harder than expected.

This doesn’t necessarily mean something is wrong. It often means the body is still adapting to the balance between medication, sleep, nutrition, and training load.

Over time I’ve learned to pay attention to these signals and adjust my training when needed.

2. Fueling Becomes Extremely Important

Endurance athletes already depend on nutrition to support long workouts, but when you don’t have a thyroid, fueling can play an even bigger role.

I’ve personally noticed that simple carbohydrates sometimes support my workouts better than heavy meals before training. Quick sugars before a long run or workout can provide the energy my body needs when hormone balance isn’t perfectly aligned.

Every athlete is different but learning how your body responds to different foods becomes incredibly valuable.

3. Weight Changes Can Feel Confusing

Many people without a thyroid feel like they are working incredibly hard but not seeing the weight changes they expect.

This can be discouraging.

But the body is doing something important behind the scenes — constantly working to regulate energy, hormones, and recovery while relying on replacement medication instead of its natural system.

Sometimes the solution isn’t simply training harder.

Sometimes it’s about better recovery, smarter fueling, and patience with the process.

Endurance sports teach us something powerful: progress happens over time.

For me, living without a thyroid hasn’t stopped me from running marathons, training for Ironman races, or continuing to challenge myself as an athlete.

It simply taught me to listen to my body more closely.

To adapt when needed.

And to remember that strength is built one workout, one mile, and one small step at a time.

— Danniela IronSunshine ☀️

Because no matter where you start, progress is still possible.

A small step still takes you forward.

#IronSunshine
#NoThyroidAthlete
#EnduranceAthlete #marathontraining
#Letsdothis #IronmanTraining

#KeepMovingForward

Training Without a Thyroid Teaches You Something Important — Your Body Becomes Your Greatest Teacher

When people ask me what it’s like to train as an endurance athlete without a thyroid, the answer isn’t always about races or big accomplishments.

Most of the time, it’s about the small daily routines.

Training without a thyroid teaches you something important: your body becomes your greatest teacher.

You learn to pay attention to energy, recovery, nutrition, and timing in ways you may never have thought about before.

For me, every day begins the same way.

Because I no longer have a thyroid, I take T3 and T4 medication each morning. I always wake up about an hour before my first class so I can take my medication and give it time to absorb. It needs to sit in my stomach for at least 15 minutes before I even think about touching coffee.

And trust me… coffee is usually the next thing on my mind.

Most mornings I don’t eat right away. I typically wait until after I finish teaching my classes. However, if I’m teaching multiple classes and planning a run afterward, I’ll have something small with simple sugars before I head out.

Sometimes it’s gummy bears.
Sometimes licorice.
Sometimes Black jellybeans.
And yes… my favorite are Peeps.

It might not look like the perfect endurance nutrition plan, but over the years I’ve learned what works for my body.

And that’s the key.

Your body will teach you — if you’re willing to listen.

This week I also started adding running back into my schedule as I prepare for my first race coming up in April.

Here’s what my training week looked like.

Monday

The week started a little rough because I was still feeling sick. But movement is part of my routine, so I got up and taught my morning classes.

6:00 AM – Pilates
7:00 AM – Cardio Essentials

Even on days when energy is low, showing up matters.

Tuesday

Still feeling a bit run down, but the morning schedule continues.

5:00 AM – TRX
6:00 AM – Strength
7:00 AM – TRX

Later in the afternoon I added a light baby jog to start easing back into running again.

Wednesday

Early morning coffee and a 3-mile run before heading to the YMCA.

7:00 AM – Cardio Essentials
Quick trip to run my daughter to school

Then back to the YMCA for:

9:00 AM – Pilates

Thursday

Another early morning start.

5:00 AM – TRX
6:00 AM – Cycling

Later in the afternoon I added a steady 6-mile run as part of building back toward race training.

Friday

6:00 AM – Pilates
7:00 AM – Cardio Essentials

And in the afternoon:

6-mile run

Some weeks feel strong.
Some weeks feel like you’re just holding the pieces together.

But endurance sports — and life — aren’t about perfect weeks.

They’re about continuing to show up, adjusting when needed, and trusting that consistency over time builds strength.

Training without a thyroid has taught me to listen more closely, adapt more often, and appreciate every mile my body allows me to run.

Because every workout, every step, and every small effort adds up.

And at the end of the day, a small step still takes you forward.

— Danniela
Iron Sunshine #nothyroidathlete☀️

Can You Train for Endurance Races Without a Thyroid?

My Honest Experience YES, YOU CAN! 

One of the most common questions I get when people hear my story is simple:

“Is it even possible to train for endurance races without a thyroid?”

The short answer is yes.

But the longer answer is that it takes patience, awareness, and a willingness to learn how your body works differently.

My thyroid was removed in 2005. At the time, I had no idea how much that small gland actually affects the body — metabolism, energy levels, temperature regulation, recovery, and even mental focus.

When the thyroid is removed, your body no longer produces those hormones naturally. Instead, you rely on medication like T3 and T4 to replace them.

For someone who loves endurance sports, that creates a unique challenge.

Because endurance training already pushes the body’s energy systems to their limits.

Add thyroid hormone replacement into the mix, and suddenly things like fueling, recovery, and timing become even more important.

Over the years, I’ve learned a few things that have helped me continue training and racing.

First — energy management matters more than ever.

There are days when energy feels completely normal, and other days when fatigue hits hard. Learning when to push and when to back off has been one of the most important lessons.

Second — fueling is critical.

Many endurance athletes rely on carbohydrates during long workouts, but I’ve noticed that my body responds very differently depending on what I eat and when I eat it. Sometimes simple carbohydrates before or during longer sessions actually help sustain my energy better than heavier meals.

Third — consistency matters more than perfection.

Training with a thyroid condition means some days will feel amazing and others will feel frustrating. What matters most is continuing to show up and building fitness over time.

Since losing my thyroid, I’ve been able to complete marathons, Ironman races, and other endurance challenges. Each race has taught me something new about how my body adapts and how powerful persistence can be.

If you’re someone living without a thyroid and wondering whether endurance sports are still possible for you, I want you to know something:

Your body is still capable of incredible things.

It may take more awareness, more patience, and more learning along the way.

But progress is still possible.

And sometimes the most powerful thing you can do is simply take the next step in front of you.

"Small steps always takes you forward."

— Danniela

#nothyroidathlete 

Starting Again!

 

Life as an Endurance Athlete Without a Thyroid

For a long time, my blog has been a place where I simply shared life as it happened — training runs, races, teaching classes, raising kids, and chasing big endurance goals.

But today I want to start something new with it.

Or maybe I should say… start again.

Because there is one question people ask me more than almost anything else:

“How are you doing Ironman races without a thyroid?”

It’s a fair question.

Back in 2005 my thyroid was removed. For many people, that kind of diagnosis changes everything. Energy levels change. Metabolism changes. Doctors often encourage people to slow down and manage their health carefully.

But before I go any further, it helps to understand something important.

What Is the Thyroid?

The thyroid is a small, butterfly-shaped gland located in the front of your neck. Even though it’s small, it plays a very big role in how your body functions.

The thyroid produces hormones that help regulate many of the body’s most important systems, including metabolism, energy levels, body temperature, heart rate, and how your body uses nutrients for fuel.

In simple terms, the thyroid acts like a control center for how your body uses energy.

When the thyroid is working normally, it releases hormones that help keep your body balanced. These hormones influence how quickly your body burns calories, how your muscles recover after activity, and even how alert or tired you feel throughout the day.

When the thyroid is removed, the body can no longer produce those hormones on its own. That’s why people without a thyroid rely on medication such as T3 and T4 to replace the hormones the thyroid would normally produce.

These medications help regulate metabolism and energy, but they don’t always perfectly mimic the body’s natural rhythm.

That’s why people living without a thyroid can sometimes experience challenges with fatigue, metabolism, weight management, and recovery.

And while there’s truth in all of that, I also discovered something else along the way.

The human body is incredibly adaptable.

Since losing my thyroid, I’ve gone on to run marathons, complete Ironman races, train for endurance challenges, and continue doing what I love most — moving my body and helping others move theirs.

Has it been easy?

Not always.

There are days when energy crashes harder than expected. Days when fueling feels like a science experiment. Days when medication timing, hormones, recovery, and training all seem to collide at once.

But there’s also something powerful that happens when you stop seeing your body as broken and start learning how it works.

You adapt.
You listen more closely.
You learn patience.
And you realize that limits aren’t always where we think they are.

For years I’ve quietly lived this life — training, racing, coaching, and teaching fitness classes in my community.

But recently I started thinking about something.

There are so many people out there dealing with thyroid issues who believe their athletic days might be over.

Maybe they were told to slow down.

Maybe they feel like their body doesn’t respond the way it used to.

Maybe they simply don’t see anyone showing what’s still possible.

So, I’ve decided to use this space a little differently moving forward.

IronSunshine will still be about endurance, racing, and life — but I’ll also start sharing what it actually looks like to train, fuel, and compete as an athlete without a thyroid.

The good days.
The frustrating days.
The lessons learned from thousands of miles and countless workouts.

If you’re someone navigating life without a thyroid, I hope this space reminds you that your body is still capable of more than you might think.

And if you’re simply someone who loves endurance sports and the lessons they teach us, I’m glad you’re here too.

Because at the end of the day, endurance isn’t just about racing.

It’s about continuing to move forward — even when progress feels small.

Because a small step still takes you forward.

— Danniela
IronSunshine ☀️

#NoThyroidAthlete
#IronSunshine
#EnduranceAthlete
#ThyroidWarrior
#StrongOver50