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The undeniable link between thyroid hormones, energy & metabolic rate

When it comes to the thyroid gland, most people’s understanding is often limited to its influence on weight – an oversimplification of its critical role in our wellbeing. This small, butterfly-shaped gland nestled in the front of our throat does far more than tip the scales; it’s pivotal in regulating our energy levels and metabolic rate. The reason thyroid hormones are so intricately linked to weight loss or gain is because of the way they drive metabolic rate – every cell in the body needs them. This then impacts on whether you experience an availability of energy or not. While a deep, unrelenting fatigue or a “tired but wired” feeling can be the result of a wide variety of body systems or organs not working optimally, a tiredness-in-your-bones-type feeling can certainly be related to poor thyroid function. Here’s how it all works.

A growing number of people in developed countries are experiencing thyroid problems. Some have a fully developed disease, such as hypothyroidism, Hashimoto’s thyroiditis, hyperthyroidism or Graves’ disease. With the latter two conditions, there is an increase in the metabolic rate, which can create an intense feeling of energy. (Some people describe it as a hyperactive or anxious feeling that they can’t control.) For others, however, their thyroid gland simply isn’t working optimally, which may be due to any of a variety of causes —nutrient deficiencies, the overconsumption of substances that can interfere with optimal thyroid function, excess estrogen and a lack of progesterone, or infection. Autoimmune diseases of the thyroid have increased significantly in the recent past as well. Let’s explore this gland, how it works and how it impacts on energy and metabolism.

The thyroid gland

The thyroid gland is part of a sophisticated network involving other glands. It begins with a chain reaction that starts in the brain and ends with the release of hormones that either boost our energy or slow us down. This cascade is essential for our day-to-day functioning, affecting everything from our heart rate to how well we sleep. This means that if there is a problem with thyroid hormone levels, or with debilitating symptoms indicating something with thyroid function is awry, then it is essential to get to the heart of the matter so that treatment can be appropriately targeted. Understanding the road into a dysfunction in the body is critical, as correcting this is the road out.

The thyroid function cascade begins with the hypothalamus, a region in the brain that makes a hormone that sends a signal to the pituitary gland, also in the brain. The pituitary then makes a hormone called thyroid-stimulating hormone (TSH) that signals the thyroid to make one if its hormones, known simply as T4 (thyroxine). T4 is found in the blood in two forms, namely “T4” and “free T4” (FT4). They are the same hormone, except that FT4 is “free” to enter tissues while the other is bound up and unable to enter tissues, which is where the work needs to be done. However, as T4 and FT4 are inactive hormones, they must be converted into the active thyroid hormone called T3 (triiodothyronine). It is T3 that helps you feel energised, drives your metabolic rate, helps to regulate your temperature and sensations of heat and cold, and contributes to your capacity to use body fat efficiently as a fuel.

Thyroid nutrients

The production of thyroid hormones is heavily dependent on a number of nutrients: iodine, selenium, zinc and iron. Unfortunately, modern diets and also soil often lack these critical minerals, contributing to potential thyroid issues, that in their right amount, help to generate an energised feeling and literally light up your metabolic rate. Iron is another mineral critical to the creation of healthy thyroid hormone production, yet iron deficiency is the most common nutrient deficiency in the world. There are numerous reasons for this, including: inadequate dietary intake; poor absorption due to (for example) poor gut function; gluten intolerance; coeliac disease; eating calcium-rich foods at that same time as iron-rich foods, as iron and calcium compete for absorption and calcium wins each time, as it is a bigger molecule; regular, excessive menstrual blood loss; or infection. Helicobacter pylori is a common one that sequesters iron for its own use. Stress can be another contributor as when someone has chronically elevated cortisol, instead of T4 being converted into the active T3 hormone, too much gets converted into reverse T3 (rT3), which creates an additional problem for great energy, not to mention a healthy metabolic rate, due to rT3 taking up receptor site positions where T3 is supposed to bind.

The role of the mitochondria

Thyroid hormones are like the spark-plugs of the body. They ignite the body’s metabolic activities, driving everything from how quickly we use calories to how efficiently our heart beats. When thyroid hormone levels aren’t optimal, it’s akin to a car running without all cylinders – everything from digestion to muscle strength can be affected.

Thyroid hormones increase the metabolic rate, as well as speed up the rate of oxidation occurring in the body. (Remember, the oxidation process generates free radicals, and antioxidants are required to stop the free radicals from damaging body tissues.) The metabolic rate, in turn, impacts on every process of body functioning. This includes the metabolism of fats, carbohydrates and proteins, digestion and cardiovascular health. It affects DNA and protein synthesis, body weight, heart rate, blood pressure, respiration, muscle strength, sleep and sexual functioning, to name, in particular, a few. Thyroid hormones impact on every body system, and energy levels are compromised when levels fall too low.

To be somewhat more specific and yet still keep this description relatable, the mitochondria, which are the energy-producing units of the cell, respond to the active thyroid hormone T3 by making adenosine triphosphate, or ATP, in the biochemical pathways known “as glycolysis and the carboxylic acid cycles”. These processes require many nutrients, including a range of B vitamins and iron. This amazing process produces ATP, the actual substance the body uses to power its many actions.

Once ATP is formed in the mitochondria, the cells must also be able to use it effectively. So the ATP is converted to another substance called adenosine diphosphate (ADP), which must then be recycled back to ATP. Yet again, many nutrients are needed to utilise ATP efficiently and recycle it properly. If any of the nutritional factors are lacking, thyroid hormones will be ineffective in increasing energy production. Reason again why nothing in the world can replace consistently eating nutrient-dense food.

Towards a healthier thyroid

While the mechanics of thyroid function might seem daunting, the pathway to supporting this gland is less so. Incorporating a nutrient-rich way of eating, paying attention to potential symptoms of dysfunction, and seeking professional advice when necessary can all contribute to better thyroid health and, by extension, a more vibrant life.

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