Your thyroid gland may be small, but it plays a huge role in keeping your body running smoothly. Located in the front of your neck, this butterfly-shaped gland produces hormones that regulate metabolism, energy levels, mood, and even heart rate. When your thyroid doesn’t produce enough hormones — a condition called hypothyroidism or low thyroid function — all of your body’s systems slow down.
Recognizing the early signs of thyroid imbalance can help you get the right diagnosis and treatment before symptoms worsen. Low thyroid hormone levels affect the vast majority of the population, yet only a relatively small percentage of them are diagnosed and properly treated.
What Causes Low Thyroid Function?
Hypothyroidism can develop for several reasons, including:
- Autoimmune disease (Hashimoto’s thyroiditis) — the most commonly cited cause per conventional medicine, where the immune system attacks the thyroid.
- Iodine deficiency — essential for thyroid hormone production. There is widespread iodine deficiency in most of the world. In the US, experts estimate that 75-90% of people are iodine deficient.
- Certain medications interfere with hormone synthesis.
- Thyroid surgery or radiation treatments.
- Aging and hormonal changes (especially in women).
Regardless of the cause, the symptoms often overlap and may develop gradually over time.
Top Signs of Low Thyroid Hormone Function
1. Persistent Fatigue and Low Energy
One of the most common symptoms is ongoing tiredness, even after a full night’s rest. When thyroid hormone levels drop, metabolism slows down, leading to low energy and sluggishness throughout the day.
2. Unexplained Weight Gain
If you’re gaining weight despite no major changes in diet or exercise, your thyroid could be underactive. A slower metabolism means your body burns fewer calories, causing gradual weight gain.
3. Feeling Cold All the Time
Thyroid hormones help regulate body temperature. Low levels can make you more sensitive to cold weather and cause cold hands or feet. The telltale sign is for you to consistently feel colder than others in the same environment.
4. Dry Skin, Hair, and Nails
An underactive thyroid reduces oil production in the skin, leading to dryness, brittle nails, and hair that may become coarse or thin. Some people also experience hair loss.
5. Brain Fog and Poor Concentration
Hypothyroidism can affect mental clarity, memory, and focus. Many people describe it as “brain fog” — difficulty concentrating or feeling mentally slower than usual.
6. Depression or Low Mood
Thyroid hormones are closely linked to neurotransmitters that regulate mood. Low levels can lead to sadness, anxiety, or depressive symptoms.
7. Constipation and Sluggish Digestion
Thyroid hormones help keep the digestive system moving. Low hormone levels can slow digestion, leading to constipation or bloating.
8. Slow Heart Rate
A low thyroid often leads to a slower pulse and may cause fatigue or dizziness during physical activity.
9. Puffy Face or Swelling
Some individuals with hypothyroidism notice facial puffiness, especially around the eyes, due to fluid retention.
10. Irregular or Heavy Menstrual Periods
In women, low thyroid function can cause changes in the menstrual cycle — such as heavier, longer, or more painful periods — and may also affect fertility.
How Is Low Thyroid Diagnosed?
If you suspect thyroid issues, your doctor can confirm it through simple blood tests, including:
- TSH (Thyroid-Stimulating Hormone): The first test typically used to detect an underactive thyroid. Many experts question its reliability.
- Free T4 and Free T3: Measure actual thyroid hormone levels in the blood. Of these, T3 is the most important as it is the active form of thyroid hormone.
- Thyroid Antibody Tests: Used to check for autoimmune thyroid disease like Hashimoto’s.
- Another method is to simply monitor your morning temperature since the thyroid regulates body temperature. This must be done first thing in the morning, before getting out of bed, to be accurate. Even a 1 degree reduction is a positive indicator that the thyroid is underproducing.
Managing and Supporting Thyroid Health
Treatment for hypothyroidism usually involves thyroid hormone replacement therapy, prescribed by your healthcare provider. However, lifestyle changes can also support thyroid health naturally:
- Eat iodine- and selenium-rich foods, such as seaweed, fish, eggs, and Brazil nuts. The best known and longest used iodine supplement is called Lugol’s Iodine. It was first developed in 1829 for use against TB and other infections.
- Reduce stress, which can impact hormone balance. I know that is easier said than done, given the current state of the world.
- Exercise regularly to improve energy and metabolism.
- Avoid extreme calorie restriction, which can further permanently slow thyroid function.
Conclusion:
Low thyroid hormone function can affect your entire body — from metabolism and mood to skin and heart health. If you’re constantly tired, gaining weight without reason, or feeling unusually cold, it’s worth getting your thyroid checked.
With proper testing, treatment, and lifestyle support, most people can restore balance and regain their energy, clarity, and well-being.
Of course, as important as hormones like thyroid are, there’s more to optimizing health than hormones alone. To help put things in proper perspective, I’ve developed something I call the 6 Pillars of Health and the 5Ms of Healing. Enhancing & optimizing each of these will have a huge positive impact on your health. These are the kind of things that we look at when making hormonal balancing recommendations.
6 Pillars of Health: 1. Sound Body Structure; 2. Proper Nutrition; 3. Appropriate Exercise & Physical Activity 4. Sound Sleep & Recovery; 5. Mental Attitude/Stress; 6. Environment
The 5Ms of health & healing are: 1. Microvascular health; 2. Mitochondrial health; 3. Metabolic health; 4. Muscle/Metabolic Reserves; 5. Membranes