What Are Hormones? A Beginner’s Guide
If you have ever wondered why you feel full of energy some days and flat on others, why your mood shifts, or how your body “knows” when it is time to sleep, you are really asking questions about your hormones.
In day‑to‑day practice, I often hear people blame their hormones for weight changes, skin issues, low energy, or sleep problems. And often, hormones do play a role. But what exactly are they?
This article will walk you through what hormones are, how they work, and simple ways you can support healthy hormone balance.
Your Body’s Chemical Messaging System
A helpful way to think about hormones is as your body’s chemical messengers.
Imagine your body as a large organisation. Your brain is the CEO, but it needs a way to send instructions to all the different departments: your heart, liver, muscles, skin, and so on.
For quick, instant messages (like pulling your hand away from something hot), your body uses the nervous system, which is like a phone call.
For longer‑term instructions (such as growth, metabolism, and reproduction), your body uses hormones, sent through the bloodstream, like carefully written emails.
Hormones are produced by special organs called glands. Together, these glands form the endocrine system. Once released into the blood, hormones travel throughout the body to deliver messages to specific cells.
The “Lock and Key” Mechanism
You might wonder: If hormones travel everywhere in the blood, why don’t they affect every single cell?
This is where the “lock and key” idea is useful:
The key is the hormone.
The lock is a specific receptor on or inside a cell.
A hormone can only “unlock” and act on cells that have the right receptors. For example, thyroid hormones circulate widely, but they will only trigger a response in cells that have thyroid hormone receptors.
Meet Some of the Key Hormones
There are many hormones in the body, but a few play particularly important roles for most Australian adults.
1. Hormones That Influence Energy and Metabolism
Thyroid hormones (T3 and T4): Produced in the thyroid gland in your neck. They act like your internal thermostat and speedometer, helping to control how quickly your body uses energy.
If levels are too low, you may feel tired, cold, or notice weight gain.
If levels are too high, you may feel anxious, sweaty, or notice weight loss.
Insulin: Produced by the pancreas. Insulin helps move sugar (glucose) from your blood into your cells, where it can be used for energy. When this system is not working well, blood sugar can run high over time.
2. Hormones That Respond to Stress
Cortisol: Sometimes called the “stress hormone,” cortisol helps you wake in the morning and manage short‑term stress.
However, if stress is ongoing, cortisol can remain high for too long, which may contribute to sleep problems, weight changes, or mood changes.
Adrenaline: This is the classic “fight or flight” hormone. It increases your heart rate and prepares your body for immediate action when you are faced with a sudden challenge.
3. Reproductive and Sex Hormones
Oestrogen: A key female sex hormone (though men also have it in smaller amounts). It plays an important role in the menstrual cycle, bone health, heart health, and mood.
Progesterone: Works alongside oestrogen in the menstrual cycle and is crucial in supporting pregnancy.
Testosterone: Often thought of as the main male sex hormone (though women also produce it). It supports muscle mass, bone strength, red blood cell production, and libido.
Note: In Australia, we commonly use the spelling “oestrogen”, although you may see the American spelling “estrogen” in international articles.
How Hormones Change Over Time
Hormones are not fixed. They naturally fluctuate over the course of a day and change more broadly over a lifetime.
Hormonal Changes in Women
During the reproductive years, hormone levels follow a monthly rhythm, influencing the menstrual cycle. Major shifts occur during:
Pregnancy: Hormone levels rise significantly to support the developing baby.
Perimenopause and menopause: Oestrogen and progesterone levels gradually decline. This can lead to symptoms such as hot flushes, night sweats, mood changes, or sleep disturbance for some women.
Hormonal Changes in Men
In many men, testosterone levels are relatively steady from day to day, but tend to decline gradually with age. This slow reduction is sometimes referred to (informally) as “andropause.”
While this change is usually more gradual than menopause, some men do notice changes in energy, mood, muscle mass, or libido over time.
Possible Signs of a Hormone Imbalance
Because hormones affect many body systems, imbalances can show up in different ways. Some common signs that may prompt a discussion with your doctor include:
Unexplained weight changes
Gaining or losing weight without significant changes in your usual eating or activity patterns.
Ongoing fatigue
Feeling very tired even after what should be adequate rest or sleep.
Changes in mood
Persistent anxiety, irritability, low mood, or feeling “not yourself.”
Temperature sensitivity
Feeling unusually hot or cold compared with the people around you.
These symptoms do not always mean there is a hormone problem, but they are good reasons to seek medical advice.
Everyday Ways to Support Hormone Health
Some hormone conditions need specific medical treatment, such as insulin for diabetes or thyroxine for an underactive thyroid. However, lifestyle choices can make a meaningful difference to overall hormonal health.
Here are three evidence‑based areas to focus on:
1. Protect Your Sleep
Sleep is one of the most powerful “reset” buttons for your hormones.
Poor or irregular sleep can affect hormones that control hunger and fullness (such as leptin and ghrelin).
Many people notice stronger cravings for sugary or highly processed foods when they are sleep‑deprived.
Aim for a regular sleep routine where you go to bed and wake up at similar times each day, in a dark and quiet environment where possible.
2. Choose Lower GI, Less Processed Foods
Large spikes in blood sugar can lead to large spikes in insulin.
A way to help keep insulin steadier is to base meals around whole grains, vegetables, fruits, legumes, nuts, seeds, and lean proteins, and to reduce highly processed, high‑sugar foods.
Australian dietary guidelines support this style of eating to reduce the risk of long‑term health problems, including type 2 diabetes and heart disease.
If you are unsure where to start, your GP can refer you to a dietitian for personalised advice.
3. Manage Stress in Sustainable Ways
Chronic stress can keep cortisol levels elevated, which may affect sleep, appetite, and even reproductive hormones over time.
Helpful strategies can include:
Regular movement, such as walking, swimming, or cycling
Relaxation practices, such as deep breathing, meditation, or yoga
Making time for meaningful connection with friends, family, or community
Even small, consistent changes can add up over time.
When to See Your GP
If you have been feeling “off” for a while and cannot put your finger on why, you do not need to simply push through.
In Australia, your General Practitioner (GP) is the best starting point. They can:
Talk through your symptoms and medical history
Arrange blood tests to check areas such as thyroid function, blood sugar, and sex hormone levels
Refer you to an endocrinologist (a doctor who specialises in hormone conditions) if needed
Reaching out early can help identify issues sooner and give you more options for management.
Trusted Australian Resources
For reliable, up‑to‑date information about hormones and related conditions, you may find these resources helpful:
Healthdirect: www.healthdirect.gov.au
Jean Hailes for Women’s Health: www.jeanhailes.org.au
Healthy Male (Andrology Australia): http://www.healthymale.org.au