Hormonal & Genetic disorders of metabolism

Hormonal & Genetic disorders of metabolism

Hormones help regulate the metabolism. Some of the more common hormonal disorders are concerned with the thyroid. This gland secretes hormones to regulate many metabolic processes, including energy expenditure (the rate at which kilojoules are burned).

Thyroid disorders include:

• Hypothyroidism (underactive thyroid) – the metabolism slows because the thyroid gland does not release enough hormones. A common cause is the autoimmune condition Hashimoto’s disease. Some of the symptoms of hypothyroidism include unusual weight gain, lethargy, depression and constipation
• Hyperthyroidism (overactive thyroid) – the gland releases larger quantities of hormones than necessary and speeds the metabolism. The most common cause of this condition is Graves’ disease. Some of the symptoms of hyperthyroidism include increased appetite, weight loss, nervousness and diarrhoea.

Genetic disorders of metabolism

Our genes are the blueprints for the proteins in our body, and our proteins are responsible for the digestion and metabolism of our food. Sometimes, a faulty gene means we produce a protein that is ineffective in dealing with our food, resulting in a metabolic disorder. In most cases, genetic metabolic disorders can be managed under medical supervision, with close attention to diet.

The symptoms of genetic metabolic disorders can be very similar to those of other disorders and diseases, making it difficult to pinpoint the exact cause. See your doctor if you suspect you have a metabolic disorder.

Some genetic disorders of metabolism include:

• fructose intolerance – the inability to break down fructose, which is a type of sugar found in fruit, fruit juices, sugar (for example, cane sugar) and certain vegetables
• galactosaemia – the inability to convert the carbohydrate galactose into glucose. Galactose is not found by itself in nature. It is produced when lactose is broken down by the digestive system into glucose and galactose. Sources of lactose include milk and milk products, such as yoghurt and cheese
• phenylketonuria (PKU) – the inability to convert the amino acid phenylalanine into tyrosine. High levels of phenylalanine in the blood can cause brain damage. High-protein foods and foods containing the artificial sweetener aspartame must be avoided.

Metabolism and age-related weight gain

Muscle tissue has a large appetite for kilojoules. The more muscle mass you have, the more kilojoules you will burn.

People tend to put on fat as they age, partly because the body slowly loses muscle. It is not clear whether muscle loss is a result of the ageing process or because many people are less active as they age. However, it probably has more to do with becoming less active, as research has shown that strength and resistance training can reduce or prevent this muscle loss.

If you are over 40 years of age, have a pre-existing medical condition or have not exercised in some time, see your doctor before embarking on any new fitness program.

Things to remember

• Metabolism refers to the countless chemical processes going on continuously inside the body that allow life and normal functioning.
• The amount of kilojoules your body burns at any given time is affected by your metabolism.
• Your metabolic rate is influenced by many factors, including age, gender, muscle-to-fat ratio, amount of physical activity and hormone function.