Crippling fatigue is a common symptom among women with Hashimoto’s. It also tends to get worse with physical exertion, often sending us to the couch for days. Yet, to combat the weight gain, many Hashimoto’s ladies resort to typical exercise advice, which could range from focusing on gentle yoga, pilates, walking, and swimming to full training programs for those without Hashimoto’s. These can make your fatigue worse and don’t really help with weight loss.
For almost 10 years, I made the mistake of doing back-to-back spinning classes almost every day to try to lose weight with Hashimoto’s. In hindsight, it made everything worse. I was tired to the bone and so brain-fogged that I would forget mid-sentence what I was trying to say to my patients. It was not until I figured out the right way to exercise and address the root causes with a functional medicine practitioner that things finally turned around. Now, I have the energy to be a present, patient mom and guide fellow Hashi’s ladies to boost their energy and lose stubborn weight.
It might be mind-boggling to think that exercise can fix crippling fatigue. In this article, I’ll cover how working out smarter can boost your energy with Hashimoto’s. Most women, when they come to me, are burning themselves out and making things worse with their workouts.
First, let’s talk about what causes fatigue with Hashimoto’s. Then, we’ll cover how exactly exercise helps or hurts Hashimoto’s fatigue.
What causes fatigue in women with Hashimoto’s and how does exercise reduce fatigue?
Low thyroid hormone makes you tired because of the following, all of which are partly helped by exercise.
- Low thyroid hormone slows down circulation, which means less blood flow to the brain and low oxygen levels. Exercise temporarily boosts your circulation.
- Thyroid hormones work by stimulating the mitochondria, your cell’s energy production powerhouses. Low thyroid hormones mean lower mitochondrial function, so your cells produce less energy overall. Conversely, exercise boosts mitochondrial function and stimulates the production of new mitochondria [1].
- The autoimmunity that comes with Hashimoto’s means more inflammation and oxidative stress, which can make you tired. Exercise temporarily produces a small amount of inflammation and oxidative stress. In the short term, exercise should make you more tired but in the long term, exercise helps your body adapt to be able to counteract the inflammation and oxidative stress in your body. These long-term benefits happen through proper rest periods between sets and recovery days between your workout sessions.
- Low thyroid function lowers energizing neurotransmitters (substances that your neurons use to talk to one another) in the brain, such as noradrenaline, adrenaline, and dopamine [2,3]. Exercise generally boosts all neurotransmitters, which explains why it helps with depression and brain function [4].
These biochemical changes due to exercise explain why most people feel more energized immediately after exercise. It also explains why, if you exercise too close to bedtime, it can keep you awake.
However, after a few hours, the fatigue will set in because exercise increases fatiguing substances in your brain. These include oxidative stress, inflammatory cytokines, and adenosine (the molecules blocked by caffeine).
Let’s say your body has a “fatigue bucket” for these fatiguing molecules. If it overflows, you’ll feel tired and need to sleep.
Now, there are other factors that add to Hashimoto’s fatigue that exercise doesn’t help, including
- Nutrient deficiencies and anemia
- Suboptimal sleep
- The wrong dose of thyroid medications, so your levels are normal but you still have symptoms.
Uncontrolled inflammation from other sources, such as food and mold exposure

Why does exercise seem to make Hashimoto’s fatigue worse?
If in theory, exercise should energize you, why does exercise seem to send you to the couch?
The short answer is that the dose makes the poison.
Exercise works on the principle of “what doesn’t kill you makes you stronger.” It delivers many of its health benefits by creating small amounts of inflammation and oxidative stress. When the inflammation and oxidative stress are lower than your body’s threshold, your body will heal from them and get better at controlling inflammation and oxidative stress in the long run. However, it’s possible to exceed this threshold by overdosing on exercise, causing excess inflammation, oxidative stress, and wear and tear on the body.
When you have Hashimoto’s, your threshold for overdosing on exercise is much lower than in healthy people. However, at the right dose within your capacity, exercise reverses many causes of Hashimoto’s fatigue.
This is because Hashimoto’s increases many of the fatiguing substances, like inflammation, oxidative stress, and adenosine [5].
So, when you push through your fatigue and joint pain to do hour-long Crossfit classes or cardio sessions, chances are it’s too much for you. You’ll inevitably overflow your fatigue bucket and it will most likely send you to the couch for a long nap and rob you of your motivation to exercise any further.
If you have exercise intolerance, your heart may also struggle to keep up with the usual exercise intensity and duration that healthy people can do. So, attempting to do such workouts can make you very sick.

How to exercise to reduce fatigue with Hashimoto’s
I’ve found that the key to reaping the benefits of exercise is to use the smallest possible dose that produces the results and work within your capacity. That way, you avoid overflowing your fatigue bucket.
First, you have to stop thinking about exercise as a way to burn calories, and instead as a stimulus to get stronger and build muscles.
If you rely on exercise alone, your metabolism will eventually adapt to burning the same number of calories, especially if you do the same thing at every exercise session [6]. The weight loss will plateau fast and result in abysmal fat loss compared to caloric restriction.
The key to preventing a plateau is to keep challenging your body with functional movements and pushing for progress at every workout.
Progressive overload means you get better at the exercises with each and every session, such as being able to:
- Lift heavier for the same exercise
- Lift the same weights faster, with better form or more ease. We call the difficulty rating “rate of perceived exertion,” which is how you call the difficulty on a scale of 1 to 10. You want the difficulty to be 7-8 out of 10 for each of your workouts. But what you felt was 7-8 out of 10 last month can feel like 3-4 out of 10 today. This is progress.
- Lift the same weight with more reps
The progressive overload will help build muscles, which burn calories. At the same time, muscles help you better control inflammation and activate your thyroid hormones, which will improve your energy in the long run [7,8].
What’s the minimum effective dose to get stronger and build muscles?
Minimum effective dose of resistance training to get stronger
In a systematic review, lifting a single set of 6-12 repetitions at 70-85% of 1-rep max 2-3 times a week was enough to produce a suboptimal but significant increase in strength gains [9]. This means you only need to do 1 set at sufficient intensity (7-9 out of 10) 2-3 times a week to get stronger. The key is to push for progress every time.
Another pilot study looked at 10 powerlifters, divided into two groups.
Group 1: Training by lifting just one set and one rep of the heaviest weight possible, and try to push for heavier every day
Group 2: Training with multiple (4-10) sets and variable repetitions like the traditional powerlifting program
They found that group 1 got significantly stronger in 10 weeks, whereas many of the powerlifters in the latter group got weaker [10]. The authors concluded that it doesn’t take a lot for beginners to get stronger, and lower volume is better for getting stronger.
Minimum effective dose of resistance training to gain muscles
When it comes to gaining muscles, another systematic review suggests that more is better [11]. However, the review also says that you can gain a substantial amount of muscle training 4 sets per week or less per muscle group. New research also shows that you don’t need the so-called “bodybuilding reps” of 6-12 to optimally gain muscles. Rather, you just need to pick up a heavy weight and lift it enough reps that the last two feel difficult.
Conclusion
I created Thyroid Strong based on this principle to address the factors that make you tired. This means:
- Using the right warmup and breathing techniques to boost oxygenation and activate your nervous system
- Lift heavier weights with a lower number of reps with perfect form to avoid injuries
- Avoiding exceeding your fatigue bucket by giving yourself plenty of rest between sets and limiting training sessions to 20-30 minutes. Studies show that this is enough to produce results as long as you challenge yourself every session. You want to feel the rate of perceived exertion at 7-8 out of 10, not 9-10 out of 10. This is the sweet spot where you grow muscles and get stronger without getting wiped out.
This, combined with a diet guide, results in a powerful program to improve your energy levels, lose fat, and achieve a toned look. Hundreds of Thyroid Strong students have gone through the program. Many of them finally achieved remission and got their energy back.
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References
Article's References
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