I am completely frank in my reply, because there seems to be a common misconception that such hormone disorders are rife - and in reality, thyroid diseases are in fact highly uncommon. Indeed, less than a fraction of 1% of all overweight people have a disorder of the thyroid gland.

However, it is important that we understand how this gland can, in rare cases, upset the apple cart when it comes to achieving or maintaining a healthier weight.

Types of Thyroid Disease

The thyroid is an organ in the neck, and in some cases the upper chest, which produces essential hormones (eg. thyroxine) for controlling the body's metabolism, amongst other functions. There are three main categories of thyroid disease characterized by the levels of associated hormone production - low hormone production, normal production and high production.

The first category, a state known as hypothyroidism (literally "Under-Active Thyroid") is the one that we are concerned with here - since low thyroid hormone production, and therefore slowed metabolism, can have considerable implications for weight management.

Hypothyroidism - The Causes

Hypothyroidism may be caused not only by a disorder of the thyroid gland itself, but also by a variety of diseases that affect the hypothalamus and pituitary gland. Hashimoto's disease, also known as chronic lymphocytic thyroiditis (an inflammation of the thyroid) is the most common cause in the UK.

An iodine deficient diet, now thankfully very rare in the UK following inclusion of iodine in table salt, can also cause hypothyroidism, as can surgery and a certain number of drugs (eg. lithium, phenylbutazone). Hypothyroidism may also be evident at birth, the congenital form of the disorder. Finally, the so-called idiopathic (cause unknown) hypothyroidism is now strongly believed to be a disease of the immune system and may be associated with underactivity of the other endocrine organs and glands, as well as immune disorders such as systemic lupus, erythematosis and rheumatoid arthritis.

Hypothyroidism and Weight Gain

As mentioned, hypothyroidism slows down the metabolism and consequently may cause weight gain. Remember, if you experience symptoms including unusual and unexpected weight gain, arrange a blood test with your doctor. If hypothyroidism is diagnosed and corrected (eg. with medication) your metabolic rate and weight level should return to normal in a reasonable short period of time.

Hypothyroidism and Weight Loss

However, be warned, in a very few number of cases, even whilst on medication, overweight people with hypothyroidism may experience difficulty with weight loss. In such cases it is very important to pay particularly close attention to diet and exercise - in addition to ensuring the correct dose of medication is being taken. This strategy will often prove effective in helping these people to lose weight. Indeed, it has been revealed through extensive research that exercise is especially important for weight loss amongst sufferers of hypothyroidism.

Hypothyroidism - Typical Symptoms

The symptoms of adult onset hypothyroidism result from an overall slowing of body metabolism. The onset is usually gradual and, in most instances, the person may not recognize the early signs and symptoms which include: fatigue, lack of energy, intolerance of cold temperatures, constipation, heavy menstrual periods, and weight gain despite a diminishing appetite.

Hypothyroidism - How It Is Diagnosed

Hypothyroidism is often not diagnosed in the early stages because the signs and symptoms in adults are initially nonspecific. But an alert physician will always consider it in cases of chronic or unusual fatigue, unusual weight gain, obesity, constipation and dry skin.

Hypothyroidism - The Treatment

Medical treatment is most commonly an orally administered, synthetic preparation of L-thryoxine. In order not to "shock" the system or aggravate co-existing heart disease in older persons, the drug is first administered in small doses and gradually increased individually by regular measurements of blood hormone levels.