How Does Your Thyroid Affect Your Weight?

There's a significant relationship between your thyroid hormone status and your body weight and energy expenditure. In hyperthyroidism, the body's energy expenditure at rest increases, leading to lower cholesterol levels and weight loss. On the other hand, hypothyroidism is linked to reduced resting energy expenditure and higher cholesterol levels that lead to weight gain.

The Functions of Thyroid Gland

What does the thyroid do that makes it essential? It's a hormone gland critical in growth, metabolism, and body development. It also regulates different body functions by releasing thyroid hormones into the blood. For example, if the body needs more energy, it will produce more hormones. 

Known scientifically as glandula thyreoidea, it's located in front of the neck, just below the voice box. This butterfly-shaped organ consists of two side lobes lying against and around the tracheae, with a narrow tissue connecting them at the front.

The organ weighs approximately 20 to 60 grams, with two fibrous capsules surrounding it. The outer capsule connects to the voice box muscles and other vital nerves and blood vessels. The inner and outer capsules have loose connective tissue between them, allowing the gland to change position during swallowing. 

Meanwhile, the thyroid tissue has small individual lobules in connective tissues, which contain sacs or small vesicles known as follicles. They serve as storage for thyroid hormones.

The thyroid is an endocrine gland that produces and releases the following hormones:

• Thyroxine (T4) is the primary hormone produced and released by the pituitary gland. It doesn't affect metabolism, but once released in the bloodstream, it undergoes deiodination, which converts it to T3.
• Triiodothyronine (T3): This hormone plays a crucial role in metabolism though it's produced in smaller amounts.
• Reverse triiodothyronine (RT3): It's produced by the thyroid in small amounts. It's known to reverse the effects of T3.
• Calcitonin: It's made of C-cells and aids in regulating calcium in the blood. It also helps in bone metabolism.

The thyroid gland needs iodine to produce these hormones. Iodine is an element commonly found in iodized table salt and water. The gland traps it and then changes it to thyroid hormones. The amount of iodine you have in your body affects the levels of hormones the gland produces and releases.

Bodily Functions Affected by Thyroid Hormones

The thyroid gland is a vital part of the body because it releases thyroid hormones that are essential in various bodily functions, such as the following:

• Metabolism
• Digestion
• Breathing
• Heart rate
• Temperature
• Fertility
• Brain development and activity
• Skin and bone health

Organs and Glands That Interact with the Thyroid

The thyroid gland is part of the endocrine system, comprising glands and hormones that work together. They send signals to each other to start working. However, some hormones can suppress others.

One of the glands controlling your thyroid hormone levels is the hypothalamus found in the brain. It secretes a thyroid-releasing hormone (TRH), which stimulates the pituitary gland to secrete the same. After this, TSH stimulates the thyroid follicular cells to release T3 and T4 if your body has sufficient iodine levels.

Sometimes the body needs more thyroid hormones, and sometimes it only requires less. A thyroid test at home can help you determine your thyroid hormone levels. This is where the pituitary gland comes in. It sends signals to the thyroid gland to release the exact amount of hormones the body needs. 

Organ Systems Affected by the Thyroid Gland

The thyroid gland and its hormones also affect your body's organ systems such as the following:

• Cardiovascular System: The thyroid affects your heart rate because it regulates the amount of blood pumped by the heart in the circulatory system. It also contributes to the contractility of your heart.
• Nervous System: A poorly functioning thyroid can cause problems in the nervous system, which result in tingling, numbness, and pain in some parts of the body. Further, hypothyroidism can lead to depression, while hyperthyroidism can cause anxiety.
• Digestive System: The thyroid also plays a role in gastrointestinal motility or how food moves in the digestive system.
• Reproductive System: Once the thyroid gland fails to function correctly, it can cause irregular menstruation and infertility problems.

Thyroid Function Test

Assess thyroid function and indicate abnormal thyroid activity.

£59.00

Add to Cart ›

Thyroid Function & Autoimmune Reaction Test

Assess thyroid function and indicate abnormal thyroid immune activity.

£89.00

Add to Cart ›

How Thyroid Imbalance Affects Weight

Your Basal Metabolic Rate (BMR) increases when excessive thyroid hormone production occurs. You'll lose weight as your cells work harder, increasing energy expenditure. Your weight loss depends on how severe your hyperthyroidism is. For instance, if it's an extreme case, you must maintain your weight by increasing the calories you consume. Weight loss occurs if you fail to meet the caloric requirement, as your body will burn more calories than you're eating.

Several patients with an overactive thyroid lose weight in the long run. Metabolisms in these individuals, however, work faster and harder, and as such, they frequently feel hungrier and may gain weight in some cases.

Once your hyperthyroidism is treated, this usually reverses. Gaining back all the weight you lost is normal. You may also face the challenges of maintaining or losing weight if you have hypothyroidism. You need not worry; this is usual in hyperthyroid patients after radioactive iodine therapy or thyroid surgery.

It's the opposite scenario with hypothyroidism. You'll gain weight as your BMR decreases. However, the changes are more subtle, with an average weight increase of 2 to 5 kg. 

Did you know that the thyroid can grow, too? It's known as goitre. A diffuse goitre happens when the whole thyroid grows. Lumps can also form on it, referred to as a nodular goitre. You can get tested through thyroid scintigraphy to determine if the nodules are releasing abnormal levels of hormones. They're called "hot nodules" if they produce more than others and "cold nodules" when they make less.

Could Thyroid Hormones Help Regulate Your Weight?

Several studies have shown the potential role of thyroid hormones in body weight regulation.

In a study with overweight and obese individuals as respondents, higher baseline free T3 and T4 levels were found to be closely linked to more weight loss within the interval of six and 24 months, utilizing weight-loss diets. However, the potential of thyroid hormones being weight regulators has been tackled only slightly.

It must be noted, instead, that your lifestyle choices have crucial roles in maintaining your health. Diet and exercise are vital to your overall well-being, not only maintaining or losing weight. Both activities have several benefits and are highly useful in managing thyroid condition symptoms.

The Role of Metabolism

Metabolism occurs when the body converts food and drink into energy. During this process, food is broken down and converted into energy that your body needs to function.

Calories are burned through the performing of your daily and physical activities. Even when at rest, your body still uses energy. Your basal metabolic rate (BMR) is the efficiency at which your body metabolizes. You obtain excess energy when you eat more food than your body needs. Subsequently, this energy is stored in your fat cells, therefore increasing your weight.

Thyroid Hormones and Weight Gain

The thyroid hormone controls your body's metabolism. It comprises two main hormones – triiodothyronine (T3) and thyroxine (T4). These hormones work with your hypothalamus to maintain your energy balance and weight.

However, thyroid hormones work together with several other hormones, chemicals, nuclear receptors, and proteins to determine how much energy your body uses.

Various studies have analyzed the relationship between weight gain and thyroid hormones differently. A study conducted among obese participants proved that:

• The thyroid stimulating hormone (TSH) levels are either elevated or at the high end of the normal range.
• There are high free T3 (triiodothyronine) levels.
• There are low free T4 (thyroxine) levels.

In contrast, some studies have reported the opposite of these findings.

A 2014 study that tracked the progress of 2,102 adults with normal thyroid function for 11 years proved that TSH levels also increased as weight increased in both males and females over time. The study concluded that weight gain and TSH do not have a causal relationship, with the researchers proposing the involvement of a third factor.

Moreover, a 2017 study on participants with normal thyroid function found no link between body mass index (BMI) and TSH after a 10-year follow-up period. However, the study detected a tendency for higher BMIs in patients with lower free T4 levels.

BMI is a flawed measure as it does not consider age, body composition, sex, race, and ethnicity. However, it still is widely used in the medical realm as it's a quick and inexpensive way to interpret an individual's health status and results.

As previously discussed, the typical finding is that an underactive thyroid leads to weight gain among people as their bodies do not efficiently use calories anymore. The specific relationship is the more severe the hypothyroidism is, the higher the weight gain. That's why regularly taking a thyroid test at home is essential.

Obese adults also have autoimmune hypothyroidism between 10% to 60% of the population. Even mild hypothyroidism can result in weight gain and changing one's BMI.

The Struggles of Losing Weight

Hypothyroidism makes it more challenging to lose weight. Hormone resistance issues and low T3 levels may explain why this is the case. Discussing the best food with a nutrition professional or dietitian or knowing how much to eat can be a helpful first step.

Low T3 Levels

T3 is the thyroid hormone at the cellular level that delivers energy and oxygen to cells. Lower resting metabolic rates are linked with lower T3 levels among hypothyroid patients.

When metabolism is lowered, you need to burn more calories through more physical activity and reduce your calorie intake.

Hormone Resistance

Hormone resistance problems are common among people with thyroid disease. These problems include leptin and insulin resistance.

Leptin Resistance

Your fat cells produce a peptide hormone called leptin. It performs a variety of functions. These include stimulating thyroid hormone production to burn fat by telling your hypothalamus when to stop eating and maintaining metabolism and energy balance.

When there is excessive leptin in the body, your body is less sensitive to its signals, resulting in leptin resistance. When this happens, your hypothalamus isn't told that you have had enough to eat. It then shifts to starvation mode – telling you you're still hungry as it decreases the number of calories you burn.

The cycle goes like this: as your appetite increases, your thyroid slows your metabolism down. You eat more and burn fewer calories – with weight gain as its endpoint. Your fat cells make more leptin in congruence with the pounds you put on – enabling this cycle further.

Insulin Resistance

Insulin controls your blood sugar levels and aids your body in converting food to energy. After you eat, it signals your cells to absorb glucose (excess sugar) in your blood and use it for energy afterward.

Like leptin resistance, when insulin levels are high, your cells become less receptive to insulin signals. In effect, you need higher insulin levels to regulate blood sugar levels. Higher insulin levels increase weight gain and heighten your risk of contracting type 2 diabetes.

Insulin builds fat as it increases the amount of fat surrounding your abdominal organs. Both hypothyroidism and hyperthyroidism can trigger insulin resistance.

Your thyroid greatly affects your weight. It’s time to take regular thyroid test at home like Vitall’s Thyroid Function Home Test Kit. It’s a hassle-free, easy, and accurate hormonal control test that specifically assess thyroid function and determines abnormal thyroid activities. This finger-prick blood test kit can be done at home or clinic. It also includes three accredited laboratory tests: Free Thyroxine (FT4), Thyroid Stimulating Hormone (TSH), and Triiodothyronine (FT3). 

Summary of Thyroid Function And Weight Regulation