What Is GLP 1?
GLP 1 is a natural hormone involved in appetite, digestion and blood sugar control. Here is what it actually does, why GLP 1 medications cause weight loss and how medicines such as Wegovy and Mounjaro fit in.
GLP 1 stands for glucagon like peptide 1. Your gut naturally releases it after you eat. It helps signal fullness, stimulates insulin when blood glucose is elevated and slows how quickly food leaves the stomach. GLP 1 medications mimic or extend these effects.
What does GLP 1 stand for?
GLP 1 stands for glucagon like peptide 1. It is a naturally occurring incretin hormone released mainly from cells in your intestine in response to food.
Its job is not simply to make you lose weight. GLP 1 is part of the body’s normal system for coordinating food intake, digestion and blood glucose after a meal.
Important: GLP 1 itself is a hormone your body already makes. A GLP 1 receptor agonist is a medication designed to activate the same receptor for much longer.
What does GLP 1 do in the body?
After food enters the digestive system, GLP 1 helps coordinate several responses at once.
Food triggers GLP 1 release
Specialised cells in the gut release GLP 1 after nutrients are consumed.
Insulin secretion increases
When glucose is elevated, GLP 1 helps pancreatic beta cells release insulin.
Digestion slows
GLP 1 can delay gastric emptying, meaning food leaves the stomach more slowly.
Fullness increases
GLP 1 signalling affects appetite pathways and can reduce hunger and food intake.
Why does GLP 1 cause weight loss?
The major reason is reduced energy intake. GLP 1 receptor activation can make people feel fuller sooner and less hungry between meals.
Slower gastric emptying can also contribute to fullness, although the effects of GLP 1 medicines extend beyond simply keeping food in the stomach longer.
Less hunger
Appetite signalling can make eating less feel easier rather than relying entirely on willpower.
Earlier fullness
People may feel satisfied after consuming a smaller amount of food.
Reduced food intake
Lower appetite and increased satiety can reduce total calorie intake over time.
Better glucose control
GLP 1 signalling also improves post meal glucose regulation, which is why the drug class was first important in diabetes care.
Natural GLP 1 vs GLP 1 medication
Natural GLP 1 does not remain active for very long. It is rapidly broken down in the body.
GLP 1 receptor agonist medicines were engineered to produce longer lasting receptor activity, allowing effects to persist far beyond the short natural GLP 1 response after a meal.
| Natural GLP 1 | GLP 1 medication | |
|---|---|---|
| Source | Produced naturally in the gut | Pharmaceutical medicine |
| Triggered by | Eating | Administration of the medicine |
| Duration | Very short lived | Designed for prolonged activity |
| Purpose | Normal physiology | Diabetes and or chronic weight management depending on product |
What are GLP 1 medications?
GLP 1 receptor agonists are prescription medicines that activate the GLP 1 receptor. Some primarily target GLP 1 while newer medicines can target multiple metabolic receptors.
| Medicine | Active ingredient | Targets | Australian use |
|---|---|---|---|
| Wegovy | Semaglutide | GLP 1 | Chronic weight management |
| Ozempic | Semaglutide | GLP 1 | Type 2 diabetes |
| Saxenda | Liraglutide | GLP 1 | Chronic weight management |
| Trulicity | Dulaglutide | GLP 1 | Type 2 diabetes |
| Mounjaro | Tirzepatide | GIP plus GLP 1 | Type 2 diabetes and chronic weight management |
Mounjaro is technically different: tirzepatide activates both GIP and GLP 1 receptors, so it is a dual receptor agonist rather than a GLP 1 only medicine.
Is GLP 1 a peptide?
Yes. Natural GLP 1 is a peptide hormone made from a chain of amino acids.
This is also why names such as semaglutide and liraglutide are often discussed in peptide communities. They are engineered peptide based molecules designed to produce prolonged GLP 1 receptor activity.
Is GLP 1 the same as Ozempic?
No. GLP 1 is the natural hormone and biological pathway. Ozempic is a brand of the prescription medicine semaglutide that activates the GLP 1 receptor.
The same distinction applies to Wegovy. Wegovy also contains semaglutide, but it has different approved indications and dosing than Ozempic.
GLP 1 vs GIP vs glucagon
Newer metabolic medicines and research compounds increasingly target more than one receptor.
| Target | Simple explanation | Example |
|---|---|---|
| GLP 1 | Appetite, insulin secretion and gastric emptying | Semaglutide |
| GIP plus GLP 1 | Combines two incretin pathways | Tirzepatide |
| GIP plus GLP 1 plus glucagon | Experimental triple receptor approach | Retatrutide |
Retatrutide remains investigational and is not a TGA approved medicine in Australia.
What are the side effects of GLP 1 medications?
The most common adverse effects are gastrointestinal and can be more noticeable when treatment starts or a dose increases.
Common effects
Nausea, vomiting, diarrhoea, constipation and abdominal discomfort are commonly reported across the class.
Delayed gastric emptying
GLP 1 medicines can leave residual stomach contents despite normal fasting, which matters before anaesthesia or deep sedation.
Rare eye disorder
Australian product warnings were updated in July 2026 regarding a potential risk of NAION, a rare but severe optic nerve disorder.
Other warnings
Individual medicines carry additional precautions and contraindications, so their approved Product Information matters.
GLP 1 in Australia
GLP 1 receptor agonist medicines are prescription only medicines in Australia. Different products have different TGA approved indications.
For example, Wegovy and Saxenda have chronic weight management indications, while Ozempic is approved for type 2 diabetes. Mounjaro is approved for both type 2 diabetes and chronic weight management.
Australian law also restricts public advertising of prescription only GLP 1 medicines. Educational information should not be treated as promotion or a recommendation to use a particular prescription medicine.
What is GLP 1 FAQ
What is GLP 1 in simple terms?
GLP 1 is a natural hormone released by your gut after eating. It helps regulate appetite, insulin secretion, blood glucose and the speed at which food leaves your stomach.
What does GLP 1 stand for?
GLP 1 stands for glucagon like peptide 1.
Is GLP 1 a hormone?
Yes. GLP 1 is a naturally occurring peptide hormone and incretin produced in the digestive system.
Is GLP 1 a peptide?
Yes. Natural GLP 1 is a peptide hormone made from amino acids.
Why does GLP 1 help with weight loss?
GLP 1 receptor activation can reduce appetite, increase feelings of fullness and reduce food intake. This can produce weight loss over time when used in medicines studied for chronic weight management.
Is Ozempic a GLP 1?
Ozempic contains semaglutide, a GLP 1 receptor agonist. GLP 1 itself is the natural hormone, while semaglutide is a medicine designed to activate its receptor.
Is Mounjaro a GLP 1?
Mounjaro contains tirzepatide. It activates both GIP and GLP 1 receptors, making it a dual receptor agonist rather than a GLP 1 only medicine.
Is GLP 1 insulin?
No. GLP 1 receptor agonists are not insulin. GLP 1 signalling can stimulate insulin secretion when blood glucose is elevated.
Is GLP 1 medication available in Australia?
Yes. Prescription GLP 1 based medicines currently marketed in Australia include Wegovy, Ozempic, Saxenda, Trulicity and Mounjaro. Approved uses differ between products.