What are hormones and what do they do to your body?

Updated December 2022 | 4 min read
Expert contributors Melanie McGrice, accredited practising dietitian; Dr Sonia Davison, endocrinologist from Jean Hailes for Women’s Health
Words by Karen Burge

What are hormones? Why are they important? And how do they impact your body? Here, we reveal insights about how hormones help to keep you fit and well.

Hormones play a central role in regulating foetal growth and development, and continue to play a vital role throughout your entire life.

Hormones are part of the endocrine system – the body’s communication network – made up of specialised glands that make and release hormones into the blood, explains Hormones Australia, an information service run by the Endocrine Society of Australia.

These ‘chemical messengers’ travel to different parts of the body and control many functions and processes, including bone density, sleep cycles, appetite, heart function, growth and reproduction, mood, metabolism, temperature control, fluid balance, blood sugar control and more.

Here are some examples of how your hormones affect your health.

How do your hormones affect your sleep?

Melatonin is a hormone produced by the pineal gland in the brain. It travels around your body via the bloodstream. According to the Sleep Health Foundation, melatonin levels vary throughout the course of a day and are controlled by your body clock. Normally, melatonin production ramps up at night, helping you slip into a slumber, and dials down in bright light, helping you to wake up. If you feel sluggish in the morning, step outside for a walk in the sunshine or flood your bedroom with natural light.

Do hormones adjust to changes in your body?

Most hormone systems have a 'feedback' mechanism. Changes in your body trigger a message that’s sent back to the hormone-producing gland, resulting in an adjustment in hormone secretion, explains endocrinologist Dr Sonia Davison from Jean Hailes for Women’s Health. “[It’s] like a thermostat on a heater altering heat production according to the temperature sensed,” she says.

How does body fat influence hormones?

The female body needs a certain amount of body fat to ovulate, menstruate and fall pregnant. If a woman’s body fat level falls too low, periods and ovulation can stop. If her body fat levels are too high, this could lead to higher levels of oestrogen and oestrone, as well as an increased risk of hormone-related cancers, like breast cancer. If you’re overweight, losing a few kilos may benefit your hormone levels and your body; the opposite applies to those who are underweight.

Which hormones can affect your appetite?

If you’ve ever battled with the urge to keep eating, when you know you’ve probably had enough, the hormone cholecystokinin may have been responsible. It’s produced in the small intestine about 20 to 30 minutes after a meal and, once triggered, tells you it’s time to stop eating, explains accredited practising dietitian Melanie McGrice. If you’re looking to rein in overeating, the trick is to eat slowly, she suggests.

About four to five hours after your meal, a hormone called ghrelin is produced by the stomach to stimulate hunger and remind you it’s time to eat again. “Ignoring your hormones and skipping meals … may make you crave something higher in kilojoules later,” Melanie says, so try to choose something healthy and satisfying.

What are the signs of a hormonal imbalance?

For good health, we need our hormones to be produced in the exact way and correct amounts required by the body, Dr Davison says. Too little, too much or an inappropriate production of hormones will stop the body from functioning as well as it should, showing signs of imbalance. Hormone imbalances can lead to problems like diabetes, menstruation issues, thyroid conditions and other health concerns.

Some signs of hormonal imbalances in women and men include:

• weight gain or unexplained weight loss
• fatigue
• muscle weakness, aches, tenderness and stiffness
• increased or decreased heart rate
• constipation or more frequent bowel movements
• increased thirst or hunger
• depression, nervousness, anxiety or irritability
• infertility
• dry skin, puffy or rounded face
• hot flashes and night sweats
• decreased sex drive
• hair loss.
  

If you have an unresolved health issue, or suspect your hormones aren’t behaving as they should, see your GP.

Oestrogen and bone health – how are they linked?

According to Jean Hailes, the hormone oestrogen is essential for healthy bones. When oestrogen levels decrease, such as in menopause, bones are at a much higher risk of becoming brittle and breaking – the condition known as osteoporosis.

To check and maintain your bone health, your doctor may suggest a bone density scan or recommend lifestyle changes, like increasing the regularity of weight-bearing exercise (think fast walking, skipping, tennis, aerobics and resistance training) and improving your diet.

Adrenaline and the fight or flight response

The hormone adrenaline is released immediately during a stressful situation, and signals different parts of the body to either prepare for, or escape from, a threat (the fight or flight response). When your body is in the fight or flight response, your breathing, blood pressure and blood flow to the heart and lungs increase. It also heightens your pain threshold.

How does testosterone help both men and women?

You might think testosterone is a male-only hormone, but it plays a role in both men’s and women’s health. Testosterone is important for bone density, muscle mass, strength and libido, explains Hormones Australia. In men, it’s responsible for male sex organ development and characteristics like facial and body hair, increased body size and voice deepening. For women, testosterone plays a part in the female sex drive, energy and motivation.

To keep your hormones and health in check, experts recommend a healthy diet, regular exercise and getting a good amount of sleep each night.

What are the signs you need hormone replacement therapy?

Menopausal Hormone Therapy (MHT) the term for what was formerly referred to as Hormone Replacement Therapy (HRT), is the medical replacement of oestrogen, progesterone and sometimes testosterone. It’s also known as an effective therapy for troubling menopause symptoms.

MHT treatment comes in various forms, including pills, patches, gels and implants. If you’re not sure if you need MHT, some signs to look out for are:

• hot flushes or flashes
• night sweats
• pain, itching or burning during intercourse
• bone density loss
• low sex drive
• mood changes, including irritability
• insomnia and sleep problems.

Along with helping to relieve menopause symptoms, MHT also reduces the risk of various chronic conditions that can affect postmenopausal women, like diabetes, osteoporosis, bowel cancer and cardiovascular disease.

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