5 Signs of Underactive Thyroid in Women Over 40
Tired, gaining weight, or dealing with brain fog after 40? These could be signs of an underactive thyroid. Discover the top 5 hypothyroidism symptoms women over 40 shouldn't ignore.
What Is an Underactive Thyroid?
Where is your thyroid located? It sits at the base of your neck, just in front of your windpipe. It’s a small, but powerful butterfly-shaped gland.
So, what does the thyroid do? It produces hormones that regulate nearly every major system in your body: metabolism, energy, digestion, temperature, even brain and mood function. When it becomes underactive (also called hypothyroidism), hormone production slows down, and your whole body can start to feel like it's running on low battery.
Women over 40 are especially vulnerable to thyroid shifts due to changes in estrogen, progesterone, and adrenal health. Yet many are told their symptoms are just part of getting older. Knowing what are early warning signs of thyroid problems can help you catch issues early and get back to feeling like yourself faster.
What Thyroid Fatigue Really Feels Like
This isn’t everyday tired.
Thyroid-related fatigue is the kind that sleep doesn't fix. You might get 8 hours of rest and still wake up groggy, foggy, or unmotivated. It’s like someone dimmed your internal lights. Tasks feel harder. Energy runs out by midday. This deeper fatigue is one of the most common thyroid symptoms, and it often gets missed or misdiagnosed.
How Low Thyroid Function Affects Your Energy
Your thyroid hormones are what tell your cells to make energy. When hormone levels are low, or when your body isn’t converting them properly, your cells can’t perform efficiently. That translates into less stamina, less focus, and more time feeling drained no matter how “healthy” your habits are.
Why Thyroid Imbalance Slows Your Metabolism
Think of your thyroid as your internal thermostat. When hormone levels drop, your metabolism slows with it. You might be eating well, exercising, even tracking your calories, but still noticing weight gain, bloating, or stubborn belly fat.
It’s not in your head. Your body burns fewer calories when thyroid function is low, and it may also become more insulin resistant, leading to more fat storage and water retention.
Cold Hands and Feet
One of the most classic thyroid symptoms is feeling cold (especially in your hands and feet) even when others are perfectly comfortable.
That’s because your thyroid controls internal heat production. When hormone levels dip, your body makes less energy, which means less heat. Many women with underactive thyroids find themselves bundled up indoors or constantly reaching for sweaters and blankets.
Tracking your morning body temperature before you lift your head off the pillow (ideally above 97.8°F) can be one clue that your thyroid isn’t quite keeping up.
Thyroid and Skin, Hair, and Nails
Your hair, skin, and nails are especially sensitive to shifts in thyroid hormones.
If you’re noticing thinning hair, a change in hair texture, dry or flaky skin, or brittle nails, your thyroid could be involved. Some women even lose the outer third of their eyebrows or find clumps of hair in the shower. These changes are easy to write off as aging, but they’re often early signs of a hormonal imbalance.
Thyroid Brain Fog
Mental clarity is one of the first things to go when thyroid function dips.
Women often describe this brain fog as feeling like their thoughts are trapped in cotton. Words disappear mid-sentence, focus evaporates, and simple tasks start to feel overwhelming. You might walk into a room and forget why you’re there, or reread the same sentence three times and still not absorb it.
Mood shifts can follow close behind. Low thyroid function is commonly linked to low mood, increased anxiety, and emotional flatness.
What is Thyroid Disease?
What is thyroid disease? It’s a group of conditions, including hypothyroidism, that disrupt the way your thyroid functions.
Here’s the challenge: many women have symptoms long before their labs show a clear diagnosis. That’s because conventional testing often looks at just one marker (TSH), which doesn’t tell the whole story.
You could be in the “normal” range on paper but still feel cold, tired, foggy, and bloated. This is known as subclinical hypothyroidism. It’s a gray area where symptoms are real, but often dismissed.
This is why understanding what are early warning signs of thyroid problems matters. Don’t wait for things to get worse before seeking support.
The Thyroid–Gut Connection
When clients ask what are early warning signs of thyroid problems, we often explain that thyroid issues are rarely a standalone problem. They’re usually the final result of a cascade that starts in the gut, taxes the adrenals, and eventually impacts the thyroid.
For many, digestive issues like leaky gut, often triggered by pathogens (like Candida, mold, harmful bacteria), toxin exposures, and stress, are the first step in the chain. Bloating, constipation, or diarrhea can all be signs. A comprehensive stool panel can reveal what’s happening and help address the root cause.
When your gut is struggling, your adrenals (which produce hormones like cortisol) work harder to keep your body stable. Over time, this constant demand can deplete cortisol, along with any other hormones. This can be expedited by stressors like perimenopause, menopause, illness, loss, or even something like many sleepless nights with a newborn.
Low cortisol is a signal to investigate thyroid health, because once the adrenals are worn out, the thyroid is often next in line.
Unfortunately, most conventional blood testing stops at TSH, a single brain-to-thyroid signal marker. There are 10 total thyroid markers that can help you see the whole picture, including:
TSH (brain-to-thyroid signal)
Free T4 and Free T3 (active thyroid hormone that drives energy and metabolism)
Reverse T3 (can block active thyroid hormone)
Thyroid antibodies (to investigate possible immune activity affecting the thyroid)
This approach helps us determine whether it’s a signaling problem, a nutrient deficiency, a liver conversion issue, or an immune trigger… information you simply can’t get from TSH alone.
Get Support for Underactive Thyroid Symptoms
You deserve more than a surface-level screening.
At Ann Arbor Holistic Health, we look deeper! Using the results of a full thyroid panel (TSH, free T3, free T4, reverse T3, antibodies) alongside a detailed look at gut health, nutrient status, adrenal function, inflammation, toxin load, we can see how your body is struggling. And we can help identify things you can do at home to support your thyroid.
You’re not just a number. You’re a whole person with a story, and that story deserves to be heard.
Ready to find out if your thyroid is the missing piece? Book a free 1-on-1 consultation with one of our practitioners today to explore personalized, natural support options for thyroid symptoms, and take the first step toward feeling like yourself again.