
Hypothyroidism, or an underactive thyroid, is a common condition many women face, particularly during midlife.
The thyroid gland is essential for regulating metabolism, energy levels, and overall well-being.
When it becomes underactive, women may experience symptoms like fatigue, weight gain, and brain fog.
But why does hypothyroidism become more common in midlife, and how can diet and advanced testing, including autoantibody assessments, support thyroid health?
Why Hypothyroidism is Common in Midlife Women
Hormonal Changes During Menopause:
Midlife often coincides with menopause, during which oestrogen levels drop. Oestrogen plays a role in regulating thyroid function, and a decrease in this hormone can lead to thyroid dysfunction. As a result, many women develop symptoms of hypothyroidism around menopause, such as low energy and weight gain.
Increased Risk of Autoimmune Disease:
Hypothyroidism is often linked to an autoimmune disorder called Hashimoto’s thyroiditis, where the immune system mistakenly attacks the thyroid. Women are more susceptible to autoimmune conditions, especially in midlife, leading to a higher risk of developing hypothyroidism.
Natural Metabolic Slowdown:
Ageing also brings about a natural reduction in metabolic rate, making it more challenging to maintain energy levels and manage weight. This slower metabolism can amplify the symptoms of hypothyroidism, blurring the lines between what’s caused by thyroid dysfunction and what’s simply part of ageing.
Why Thyroid Medication Sometimes Stops Working
Many women with hypothyroidism are prescribed thyroid hormone medications, such as T3 (triiodothyronine) or T4 (thyroxine).
However, some find that their medications become less effective over time. One of the key reasons for this may be related to the body’s ability to convert T4 to T3.
Poor Conversion of T4 to T3:
The thyroid primarily produces T4, an inactive form of the hormone, which the body then converts into the active T3 form. If the conversion process is impaired, even taking T3 or T4 medication might not fully resolve symptoms. Factors such as stress, nutrient deficiencies (especially in selenium and zinc), and liver health can all impact this conversion.
Increased Reverse T3 (rT3):
Reverse T3 is an inactive form of T3 that can build up when the body isn’t converting hormones efficiently. When rT3 levels rise, the body can struggle to utilise the thyroid hormones it needs, leading to persistent symptoms even while on medication.
How an Advanced Thyroid Test Can Help
For those struggling with hypothyroidism, especially when standard treatments like T4 or T3 medications are no longer effective, an advanced thyroid test can provide valuable insights.
This test goes beyond the standard thyroid function panel, which typically only measures TSH (thyroid-stimulating hormone) and free T4.
Here’s how an advanced thyroid test, which includes autoantibody screening, may be of key importance for improving thyroid function:
Thyroid Autoantibody Testing:
An advanced thyroid test includes testing for thyroid autoantibodies, such as anti-TPO (thyroid peroxidase antibodies) and anti-thyroglobulin antibodies. These antibodies indicate the presence of autoimmune thyroid disease, like Hashimoto’s thyroiditis. Detecting these antibodies early can help identify if the thyroid is being attacked by the immune system, which may not show up in standard thyroid tests.
Identifying autoimmune hypothyroidism, Hashimoto's, is crucial because it may require a different approach to treatment, including focusing on reducing inflammation and supporting the immune system.
Assessing Free T3, Reverse T3, and Other Markers:
In addition to autoantibody testing, advanced panels typically measure free T3, reverse T3 (rT3), and T4-to-T3 conversion ratios. This gives a complete picture of how well your body is converting T4 into the active T3 hormone and whether reverse T3 is blocking its effectiveness.
By understanding how efficiently the body is using thyroid hormones, nutrition plans can be tailored, whether that involves adjusting medication with your GP or focusing on diet and lifestyle interventions.
How Diet Can Support Thyroid Health
While advanced testing can help pinpoint the underlying issues with thyroid function, diet plays a key role in managing and supporting thyroid health.
Nutritional changes can help optimise thyroid function, aid hormone conversion, and reduce inflammation.
1. Increase Iodine Intake:
Iodine is essential for thyroid hormone production. Seaweed, fish, eggs, and dairy are good sources. However, it’s important not to over consume iodine, as excess amounts can sometimes aggravate autoimmune thyroid conditions.
2. Boost Selenium and Zinc:
Selenium and zinc are vital minerals for the conversion of T4 to T3. Foods like Brazil nuts, seafood, seeds, and red meat can help ensure adequate levels. A nutritionist can also assess if supplementation is necessary to correct any deficiencies.
3. Support Liver Health:
The liver is responsible for a significant portion of the T4-to-T3 conversion, so liver health is essential. Supporting it with antioxidant-rich foods like leafy greens, cruciferous vegetables, and berries can promote better hormone metabolism.
4. Reduce Inflammation with Anti-inflammatory Foods:
Autoimmune hypothyroidism is associated with chronic inflammation. Anti-inflammatory foods, such as oily fish (rich in omega-3 fatty acids), turmeric, nuts, seeds, and plenty of vegetables, can help reduce inflammation and support thyroid function.
5. Balance Blood Sugar:
Blood sugar fluctuations can affect hormone balance. Eating balanced meals with complex carbohydrates, healthy fats, and protein can help stabilise blood sugar, which in turn supports thyroid function.
How a Nutritionist Can Help for Thyroid Problems
A nutritionist can play a vital role in helping you manage hypothyroidism, especially if your symptoms persist despite medication. Here’s how:
Personalised Nutrition Plans:
Every woman’s experience with hypothyroidism is unique, and a nutritionist can create a tailored diet plan that focuses on your specific needs, including supporting T4-to-T3 conversion, reducing inflammation, and correcting nutrient deficiencies.
Guidance on Advanced Testing:
A nutritionist can help you interpret the results of advanced thyroid tests and recommend appropriate dietary changes or supplements to support thyroid function. They can also suggest when advanced testing, including thyroid autoantibody screening, may be beneficial to gain a clearer picture of what’s happening.
Targeted Supplementation:
Based on your test results and diet, a nutritionist can recommend specific supplements, such as selenium, zinc, or omega-3s, to improve thyroid function. They will ensure that you don’t over-supplement, which can sometimes do more harm than good.
Lifestyle Support:
Stress and poor sleep can further impair thyroid function. A nutritionist can recommend lifestyle strategies such as relaxation techniques, sleep hygiene, and gentle movement to support your thyroid and overall health.
Hypothyroidism is common in midlife women due to hormonal changes, autoimmune conditions, and natural metabolic slowdown.
Advanced thyroid testing, including autoantibody screening, can offer valuable insights into thyroid health, especially when medications are no longer working effectively.
Diet and lifestyle changes can make a significant difference, supporting thyroid function and helping alleviate symptoms.
Working with a nutritionist can provide a personalised approach to managing hypothyroidism, ensuring you get the right nutrients and support to feel your best.
Nutritionist Manchester & Online

Hi I'm Lisa, I’m a BANT registered nutritionist based in Manchester UK, helping women in midlife who want to lose weight and balance hormones. I create personalised online nutrition plans for thyroid conditions such as hypothyroidism, hormone health and weight loss, which can provide a more effective and sustainable approach.
Investing in a tailored online weight loss plan, such as my nutrition programmes, or my weight maintenance programme, Keep the Weight Off After GLP-1, not only helps in balancing hormones, but also paves the way for successful, long-term weight management.
Book your FREE 30-minute call. I work online with clients across Manchester UK and Europe.
Let’s work together to reclaim your health and wellbeing!
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