Personal Trainer in London for Clients with Under-Active Thyroid (Hashimoto’s Disease)

As a personal trainer in London for over twenty years, I’ve had several personal training clients (both male and female) with under-active thyroid, and they have all been obese, with body fat levels over 40%. If you’re a personal trainer, it’s worth knowing about thyroid dysfunction and how to train a client this chronic metabolic condition.

The thyroid gland is the largest gland in the endocrine system and the main gland affecting your metabolism.  Your endocrine system comprises the glands which secrete hormones, which send biochemical instructions all around your body.

Your thyroid gland secretes three hormones, two of which are metabolic:

T3 (triiodothyronine)
T4 (thyroxine) – the main metabolic hormone
Calcitonin (not a metabolic hormone, but one which promotes bone-building)

T3 is the biologically active hormone which regulates your metabolism (the speed at which you burn energy, and the speed at which the cells and organs of your body function). T4 is converted into T3.


The two main categories of under-active thyroid are iodine-deficient and Hashimoto’s disease. Iodine is a vital building block of thyroid hormones, so a deficiency leads to an under-active thyroid.

Hashimoto’s disease is more complex. The medical profession is divided as to the exact cause and research is developing our understanding of this disease all the time. Hashimoto’s is an auto-immune disease, whereby the body’s immune system attacks the thyroid gland. It may be genetic, or the result of a viral or bacterial infection.

Another feature of Hashimoto’s which distinguishes it from iodine-deficient thyroid condition, is that Hashimoto’s sufferers also have intervals of over-active thyroid (hyperthyroidism). This results in excess thyroid hormones in the bloodstream, causing anxiety, heart palpitations, and excessively fast metabolism.


Gender: It’s more common in females.

Age: the older you are the more likely you will develop this disease.

Heredity: if the mother has the condition, the daughter is more likely to have the condition at some point in her life. (same with father/son but far less prevalent)

Other auto-immune disorders: if you suffer from another auto-immune condition such as lupus, rheumatoid arthritis, or type 1 diabetes, you are more likely to get Hashimoto’s disease.


As a personal trainer with London clients who have thyroid disorders, I like to keep up with the latest research on this condition.

One academic paper worth reading is ‘Thyroid and Obesity, An Intriguing Relationship’ by Bernadette Biondi, of the Department of Clinical & Molecular Endocrinology & Oncology, University of Naples, Italy.

This paper was first published online on 02 July 2013. It explores the link between hypothyroidism (under-active thyroid) and weight gain, or more precisely body-fat gain. It examines whether obesity is a cause or consequence of under-active thyroid, or is the relationship more complex than that? Biondi concedes that the connection between under-active thyroid and obesity is not fully understood, and that more research is needed.

The main cause of hypothyroidism in adults is auto-immune thyroid dysfunction (AITD).


These two metabolic hormones are made in the thyroid gland, from the trace mineral iodine and the amino acid tyrosine.

The pituitary gland produces TRH, thyroid-releasing hormone, which instructs the thyroid gland to release T3 and T4 into the bloodstream. The pituitary gland also releases TSH, thyroid-stimulating hormone, which does as the name suggests. Going further back in the feedback loop, the hypothalamus in the brain instructs the pituitary gland to release its hormones.

People with under-active thyroid have high levels of TSH, because the pituitary gland is pumping out more TSH in an effort to stimulate the thyroid into producing more T3 and T4.

T3 and T4 regulates glucose and lipid (fat) metabolism. This hormone also regulates thermogenesis, which is the production of heat in the body.

The more T3 and T4 that is released, the faster your metabolism, which means you burn calories at a faster rate. The less of these hormones released, the slower your metabolism, and the more prone you are to weight gain, and higher levels of LDL cholesterol (bad cholesterol).

Biondi explains that under-active thyroid is 5 – 10 times more common in females than males, accounting for 1.5 – 2% of the female population.


Low metabolism, resulting in rapid weight-gain and difficulty in losing that weight
Water retention (edema)
Reduced ability for the body to keep itself warm
Lack of energy, sluggishness, poor concentration, poor memory

Low mood, depression
Reduced appetite
Muscle stiffness, painful joints (particularly knees)


Medication in the form of synthetic T4 tablets is the most common treatment.

Exercise is recommended, as it stimulates your metabolism and also your mood. However, high-impact exercise is not recommended for those with under-active thyroid, as people with this condition often have joint-pain. Walking, swimming, and recumbent exercise bike are advised if you have bad joints.

As a personal trainer in London with clients suffering thyroid conditions, I have learnt that no two people with under-active thyroid are the same. Each individual differs in type and severity of symptoms, so any exercise regime must take this into account.


My London clients know that my personal training approach emphasises optimum nutrition. If you have Hashimoto’s disease, you need to be very careful with your nutrition, as it has a huge impact on your condition.

In short, avoid junk food, sugary drinks and processed foods. Avoid caffeine. Go organic. Go gluten-free. Eat plenty of protein to boost T3 hormone production. Eat lots of ‘good fats’ which help your body in many ways (sunflower seeds, avocados). Don’t cut out carbs altogether but focus on things like quinoa and brown rice. Eat foods rich in iodine, such as seaweed. You can buy dried seaweed from Japanese food shops and also online from Mara Seaweed.

If you live in London and hire me as your personal trainer I will go into the nutrition side of things in a lot more detail.

(Dominic Londesborough is a personal trainer in London and an online nutrition coach.)

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