What is GLP-1?
GLP-1 stands for glucagon-like peptide-1 — a naturally occurring hormone produced in the gut in response to eating. It plays several roles in metabolic regulation: it stimulates insulin secretion in a glucose-dependent manner, suppresses glucagon release, slows gastric emptying, and acts on appetite-regulating centres in the brain to promote satiety.
GLP-1 receptor agonists are a class of prescription medications that mimic these effects by binding to and activating the same receptors that natural GLP-1 activates. They were initially developed for type 2 diabetes management and have since been studied extensively for their effects on body weight.
A related but newer drug class — dual GIP/GLP-1 receptor agonists — activates both the GIP (glucose-dependent insulinotropic polypeptide) receptor and the GLP-1 receptor. Tirzepatide (Mounjaro) is the first approved representative of this class in Australia.
GLP-1 Medications Available in Australia
The following GLP-1 and GIP/GLP-1 medications are registered on the Australian Register of Therapeutic Goods (ARTG) and available in Australia with a valid prescription:
| Medication | Active Ingredient | Mechanism | Frequency | TGA Indication |
|---|---|---|---|---|
| Ozempic | Semaglutide | GLP-1 agonist | Weekly injection | Type 2 diabetes |
| Wegovy | Semaglutide 2.4mg | GLP-1 agonist | Weekly injection | Weight management |
| Mounjaro | Tirzepatide | Dual GIP + GLP-1 agonist | Weekly injection | Type 2 diabetes / weight management |
| Saxenda | Liraglutide 3mg | GLP-1 agonist | Daily injection | Weight management |
| Victoza / Ozempic OG | Liraglutide / Semaglutide lower dose | GLP-1 agonist | Daily / weekly | Type 2 diabetes |
All medications require a valid prescription from a registered Australian medical practitioner. Prescribing decisions are based on individual clinical assessment.
How Do GLP-1 Medications Work for Weight Management?
GLP-1 receptor agonists influence body weight through several interconnected mechanisms:
- Appetite regulation: GLP-1 receptors in the hypothalamus and brainstem play a role in signalling satiety. Activation by GLP-1 agonists influences appetite and the perception of fullness.
- Gastric emptying: These medications slow the rate at which food leaves the stomach, prolonging the sensation of fullness after eating.
- Glucose-dependent insulin secretion: They stimulate insulin release in a glucose-dependent manner, which also plays a role in metabolic regulation.
For dual GIP/GLP-1 agonists (tirzepatide/Mounjaro), activation of GIP receptors adds an additional mechanism that may amplify effects on insulin secretion and adipose tissue metabolism.
Who is Eligible for GLP-1 Medications?
Eligibility for GLP-1 medications for weight management is determined by a licensed medical practitioner. Clinical guidelines generally consider:
- BMI of 30 kg/m² or greater, OR
- BMI of 27 kg/m² or greater with at least one weight-related comorbidity (e.g. type 2 diabetes, hypertension, dyslipidaemia, obstructive sleep apnoea)
These are reference criteria from clinical guidelines and do not guarantee prescribing. Your prescriber will evaluate your full medical history, current medications, and individual health circumstances before making any prescribing decision.
GLP-1 Medications vs Other Approaches
GLP-1 medications are one component of medically supervised weight management — not a standalone solution. They are typically considered when lifestyle modifications alone have been insufficient, and are always used within a framework of clinical oversight.
Compared to older weight management medications (such as appetite suppressants), GLP-1 agonists have a different mechanism of action and a large body of clinical trial data. The choice between medication classes is always a clinical decision.