Underactive Thyroid (Hypothyroidism)

Underactive Thyroid (Hypothyroidism)

The thyroid gland may be tiny, but it plays an important role in health. An underactive thyroid (hypothyroidism) causes weight gain and sluggishness and requires a combination of medications and lifestyle and dietary changes to ease symptoms.

What Is an Underactive Thyroid?

The thyroid gland is a small butterfly-shaped gland in the neck which produces the hormones that regulate metabolism; triiodothyronine (T3) and thyroxine (T4). Approximately 90% of the thyroid hormones produced by the body is T4, which need to be converted into T3 before they can be used by cells. Hypothyroidism occurs when the thyroid gland doesn’t produce enough hormones, causing many of the body’s functions to slow. In particular, weight gain and fatigue are commonly reported.

Underactive thyroid disorders can affect both men and women, although it’s more common in women. In the UK, it is estimated that 15 in every 1000 women and 1 in every 1000 men are affected. It can also affect children, although this is fairly rare. 1 in 4000 babies are born in the UK each year with an underactive thyroid, medically referred to as congenital hypothyroidism. All babies born in the UK are tested for this when they are 5 days old.

Underactive Thyroid Symptoms

Underactive thyroid hypothyroidism symptoms can be similar to those of other conditions and often develop slowly over a period of years, which means they can easily be mistaken for something else. Common underactive thyroid symptoms include:

symptoms of an underactive thyroid

  • Tiredness
  • Weight gain
  • Low mood and depression
  • Memory loss
  • Increased sensitivity to the cold
  • Dry skin and brittle hair
  • Muscular aches and pains
  • Pins and needles in the hands and feet
  • Loss of libido
  • Irregular or heavy periods

It’s important to be diagnosed as quickly as possible so if you are concerned that your thyroid is struggling, visit your doctor. They will take a blood test (thyroid function test) to measure the levels of hormones in your blood.

Causes of Hypothyroidism

There are two common causes of hypothyroidism; the immune system and previous thyroid treatments. However, in recent years evidence has come to light that suggests hypothyroidism may, in certain cases, be due to a build-up of toxins in the body or nutritional deficiencies.

  • Immune System: Autoimmune disorders are one of the most common causes of hypothyroidism. In these cases, the immune system attacks the thyroid gland causing irreversible damage. It is thought that around 90% of people with hypothyroidism have Hashimoto’s disease, an autoimmune reaction that causes this type of damage to thyroid tissue. The exact cause isn’t clear, but there appears to be a genetic link, and Hashimoto’s disease is common in people with other autoimmune disorders such as type I diabetes.
  • Previous Treatments: The thyroid can be damaged by complications from previous treatments for thyroid cancer or an overactive thyroid, such as surgery or radioactive therapy.
  • Toxins: There is a growing school of thought that thyroid function can be impaired by exposure to environmental toxins such as pesticides. These disrupt thyroid metabolism and function, which slows the body’s metabolism and reduces potential weight loss.
  • Nutritional Deficiencies: The body needs certain vitamins and minerals to maintain healthy thyroid function. Iodine in particular, is required to produce thyroxine, while vitamin D, omega 3, selenium, zinc and vitamins A, B and D are important.
  • Pituitary Gland: The pituitary gland regulates the thyroid and a problem with this gland can have a knock on effect.

Complications of an Underactive Thyroid

When treated, many people can successfully manage an underactive thyroid. However, if left untreated, the condition can lead to serious complications, including:

  • Increased Risk of Heart Disease: Low levels of the thyroid hormone change the way the body processes fat, which results in high cholesterol. This increases the risk of atherosclerosis and angina.
  • Goitre: Goitre occurs when the thyroid gland swells forming a visible lump in the throat. If the lump remains small it may result in a hoarse voice and cough. If the lump becomes large, it may affect swallowing and breathing.
  • Pregnancy: If an underactive thyroid is under control prior to pregnancy, then there is little danger to the foetus. However, if left untreated during pregnancy, it increases the risk of pre-eclampsia, anaemia and birth defects.
  • Myxoedema Coma: This severe form of hypothyroidism is extremely rare and occurs mainly in patients with long-standing, undiagnosed hypothyroidism. This life threatening condition causes confusion, hypothermia and drowsiness, and requires emergency treatment.
  • Sleep Apnoea: Hypothyroidism can be a contributing factor to obstructive sleep apnoea. In certain cases, hypothyroidism causes changes to the upper airways, such as an enlargement of the tongue (macroglossia), which results in blockages to breathing at night. If you constantly feel tired and lethargic during the day despite having a full night’s sleep, then try a portable home monitor to test for sleep apnoea.


If a doctor has confirmed that your symptoms are caused by an underactive thyroid, there are many steps you can take to correct the problem. A comprehensive approach is needed that includes medication, diet, and lifestyle changes.


If your symptoms are severe, your doctor will likely prescribe daily hormone tablets to replace those the thyroid should be producing. Once started, this treatment will need to be maintained for the rest of your life, and may require regular blood tests until the right dose is found. For this reason, medication isn’t always the best first step for a borderline underactive thyroid, but you should still be monitored by a medical professional.


The diet plays an important role in the maintenance of healthy thyroid function, and many doctors will test for vitamin and mineral deficiencies if the thyroid is underactive. Try making these simple changes to your diet:

Increase Protein Intake: The thyroid gland is made up of protein so increasing your intake of protein can help to normalise thyroid function and control weight. Good sources of protein include nuts, legumes and grass-fed meats.

Go Gluten-Free: Gluten has a similar molecular composition to thyroid tissue, and several experts have suggested that gluten increases the autoimmune attack on the thyroid. For this reason, gluten should be avoided by those with Hashimoto’s disease. Remove any dietary burdens on the immune system by following an alkaline diet and help the body to heal itself.

Reduce Soy Intake: The isoflavones in soya-rich foods have been associated with decreased thyroid hormone production and disrupted iodine usage. Soya can also interfere with the absorption of thyroid medication.

Eat Nutrient Dense Foods: As with any diet, whole and nutrient dense foods are best for good health. A lack of certain vitamins and minerals can lead to thyroid deficiency, particularly iodine, selenium and zinc. Some people with hypothyroidism struggle to absorb and metabolise vitamins and minerals due to low stomach acid.

Iodine: More than two-thirds of the body’s iodine is secreted in the thyroid gland, which is why iodine deficiency can be behind an underactive thyroid. Table salt is often fortified with iodine, while fresh fish, eggs, and seaweeds such as kelp are good food sources.

Zinc and Selenium: Sufficient levels of zinc and selenium are needed to convert T4 into T3, which is the active form of the hormone. If you are low on these minerals the thyroid will struggle to function at optimum capacity, which has a knock on effect on the whole body. Good food sources of zinc and selenium are meat, fish, milk cheese, beans and nuts.


If you are low in certain nutrients, then taking dietary supplements will likely have a big impact on how you feel. Food supplements should be used to complement, not substitute a balanced diet:

Multivitamin: A high-quality multivitamin ensures you get sufficient levels of essential vitamins and minerals, without going overboard. Look for broad spectrum multivitamin that contains zinc 15-20mg, selenium 100-200mcg, and folic acid 400-600mcg for healthy thyroid function. Also, people with an underactive thyroid struggle to absorb vitamin B12 and vitamin D, so deficiency is particularly prevalent. Take 1mg of vitamin B12 and 400iu of vitamin D.

Kelp: This popular sea plant is abundant in vitamins and minerals, particularly iodine. Iodine is absolutely essential for the maintenance of healthy thyroxine levels and thyroid function but is needed only in small amounts, so kelp supplements are a good source. Too much can be detrimental for thyroid function, and if you are suffering from autoimmune thyroid problems, you should not use this remedy.

Fish Oil: Evidence suggests that fish oil can increase thyroid hormone uptake and improve thyroid hormone signalling within the liver. The omega 3 fatty acids in fish oil help to regulate the metabolic rate within liver cells and impact the way the liver metabolises carbohydrates, protein and fat. When the body has sufficient levels of omega 3 fatty acids, the thyroid hormones work more effectively at burning fat. Take between 1000mg to 4000mg of fish oil capsules per day.

Apple Cider Vinegar: Treatments for hypothyroidism are often about finding balance and that’s exactly what apple cider vinegar does. It helps to restore the body’s acid-alkaline balance so supports detox, weight loss, and hormone regulation. Apple cider vinegar can also benefit people with Hashimoto’s disease as it increases stomach acid, improves the absorption of nutrients, and heals any underlying digestive issues. Take apple cider vinegar capsules or add two tablespoons of apple cider vinegar to a glass of warm water and drink daily.

Thyroid Supplements can be taken safely alongside most medications to manage hypothyroidism but you should always speak to your doctor first. Also, avoid taking supplements within two hours of medications as they may interfere with their absorption and effectiveness.

Lifestyle Changes

Certain lifestyle habits have a knock on effect on the health of the thyroid. Making simple changes can help to reduce the demands on the thyroid gland:

De-stress: The adrenal glands secrete the hormones cortisol, epinephrine and norepinephrine which regulate the body’s stress response. Weak adrenal glands impair the conversion of T4 into T3 and seriously impact thyroid function. If stress is a contributing factor, you can overcome adrenal exhaustion without treating the thyroid gland directly. Try popular relaxation techniques such as deep breathing, rhythmic exercise or physical activity, mindful meditation, or massage therapy.

exercise thyroid health

Exercise Daily for 30 Minutes: Joint pain and swelling are common symptoms of hypothyroidism, so opt for low-impact aerobic exercises that increase the heart rate without putting too much stress on the joints - cycling, walking or elliptical training are all good options. Yoga and Pilates help to strengthen joints and core muscles and may ease back and hip pain associated with hypothyroidism.

One pose in particular - the shoulder stand, or Sarvangasana – may offer relief from hypothyroidism by increasing circulation to the thyroid. Whatever you do, it’s important to find activities you enjoy.

Heavy Metal Detox: Toxins and heavy metals such as mercury, aluminium, arsenic and lead accumulate in soft tissues such as fat cells and can cause the thyroid to malfunction. High levels also increase the risk of allergies, poor circulation, digestive issues, insomnia, muscle soreness, headaches, and a weakened immune system. Natural remedies such as milk thistle and chlorella bind to heavy metals and allow the body to flush them out naturally. Heat therapy, such as saunas, also helps the body to eliminate stored toxins.

Adopting some of these lifestyle and dietary changes may offer some relief from underactive thyroid symptoms, but please be aware that this is not qualified medical advice. Please consult with a doctor or healthcare professional for a diagnosis and suitable treatment plan. The British Thyroid Foundation (BTF) is a charity whose aim is to support people with thyroid disorders and is an excellent source of additional evidence-based information.