Obesity isn’t about being a good or bad person. It’s about biology, and how your body metabolises energy.
Endocrinologists have long known this, but medicines like Mounjaro, Ozempic, Wegovy, Saxenda and Trulicity have mainstreamed the idea of excess weight as a medical condition rather than a moral failing.
But apart from their effect on the culture, what do we actually know in 2026 about how these drugs affect people?
“The truly important story about these medications isn’t necessarily about the weight that people lose, it’s about the improvements in health outcomes that they get,” says Associate Professor Sam Hocking, President of the National Association of Clinical Obesity Services, clinical academic at the University of Sydney, and endocrinologist with the Metabolism and Obesity Service at the Royal Prince Alfred Hospital.
“When you take these drugs, your metabolic health improves. If you’re just losing weight, but not improving health, what really is the point?”
Are these drugs safe?
“These medications have been studied in really large clinical trial development programs – over 50,000 people in the Semaglutide clinical trial program,” says Sam.
“We’ve known about this class of drugs now for around 20 years from when the first early ones came onto the market, and they really are very safe. They have a very good safety profile.”
While people with diabetes have used GLP-1 drugs for decades, media coverage of their weight-loss use often depicts them as new and scary.
“They’re not new, we know they’re really safe, and we know they’re very effective” says Sam.
In Australia, the Therapeutic Goods Administration (TGA) recently advised that Ozempic-style drugs carry warnings about potential suicidal thoughts and possible effects on contraception.
However, these warnings come from a place of extreme caution rather than from anything happening in the real world.
Previous weight-loss medications did actually cause suicidal thoughts in some people and had to be removed from sale. This made regulators extremely careful when it came to obesity medications and mental health.
Studies now show that people taking GLP-1 medicines aren’t any more likely to be depressed than the rest of us, and the FDA in the US recently removed its warning, with the TGA likely to follow.
When it comes to contraception, Ozempic-style drugs may have an effect, but it’s not because of the drugs cancelling each other out. Oral contraceptive pills are designed to travel through your digestive system a fair way before dissolving, but GLP-1 medicines slow your stomach down, which messes up the timing. It’s the same reason you have to be careful with your contraception after getting a stomach bug – going at the wrong speed through the digestive system means it might not work as well.
This means anyone using an IUD or implant as contraception won’t be affected, but if you’re taking a pill it’s best to have a chat with your doctor to see if it might be sensitive to a slowed-down digestive system.
How do they actually work?
The usual story about GLP-1 agonists is that they slow your stomach down and mimic the hormones that make you feel full, which naturally limits how much you can eat.
That’s true, but there’s another factor – their effect on the brain.
“How humans are primed to eat food is kind of really interesting,” says Sam. “There’s these deep, primitive areas of the brain – the hypothalamus and the hindbrain – that regulate our appetite and hunger. And it [the feeling of hunger] is an interface of those areas of the brain and cues that come from the rest of your body”
“When your stomach’s empty, it secretes this hormone ghrelin which tells your brain ‘you’re hungry’. And then there’s a whole host of hormones that say, ‘no, you’re not hungry, you don’t need to eat’.”
“It’s interesting that we have one hormone that tells us to eat, and all these other hormones that tell us not to. So it must be a natural thing to want to eat, if we need to have a lot of hormones to turn that off.”
So it’s easy to feel hungry but harder to feel full – and GLP-1 is one of those hormones that tell your brain you’re full. That means when you’re taking GLP-1 medications, you’re just augmenting the anti-hunger hormones that are already inside you.
But humans don’t just eat because we’re hungry. We eat because we’re bored, or sad, or tired, or it’s an occasion, or everyone else is doing it and it would be weird not to, or simply because food is great.
These reasons make eating rewarding and pleasurable, rather than just something that you do a few times a day to avoid dying.
It’s not just that they make you feel too full to eat – GLP-1 medicines might just change how much you care about eating and what it feels like when you do.
“These drugs may also work on those hedonic and pleasure responses as well,” notes Sam. “And that’s why when people use them, they report a reduction in cravings. It’s amazing how when people come to see me after they’ve started these medications, one of the first things they comment on is how their ‘food noise’ has either gone or reduced.”
Do they actually cure everything?
Many people with obesity don’t have any medical problems. But for those who do have medical conditions alongside obesity, it looks like GLP-1 medicines are really good at improving your health, whether or not you lose any weight.
“What we know is from the major regulatory trials. Those large studies have shown us that not only do you reduce your weight, but you also improve most of your cardiovascular risk factors,” explains Sam.
“So you get reductions in systolic and diastolic blood pressure. You get reductions in waist circumference (and we know visceral fat is metabolically detrimental fat). You get improvements in blood lipids, and particularly large drops in triglycerides, but also improvements in LDL cholesterol, which is that nasty cholesterol that causes blockages. You get improvements in blood glucose, and you get improvements in markers of inflammation. In people with osteoarthritis and obesity, it reduces pain; in people with sleep apnoea, tirzepatide has been shown to reduce sleep apnoea.”
“The really important study was the one that was done in people with obesity and cardiovascular disease, which showed a 20% reduction in non-fatal myocardial infarction, non-fatal stroke, and cardiovascular death.”
“What that actually tells us is that when you take these drugs, your metabolic health improves.”
However, a recent trial studying GLP-1 medicines and early Alzheimer’s didn’t show any effect, while studies about their potential as a treatment for addiction are still in the experimental stage.
Isn’t it cheating?
Sam emphasises that GLP-1 medications are for people whose weight affects their health.
“If you do not have obesity that’s detrimental to your health, you do not need to be treated” she says.
“Not everybody who’s living in a larger body has health impacts from living in a larger body. So to me, that person doesn’t have the disease of obesity.”
However, we know that for some people, excess weight can be connected to a lot of other conditions, and then it becomes a medical problem that can’t be solved with good intentions alone.
“Obesity has a biological basis” says Sam. “We know that about 40 to 70% of your body weight is determined by your genes and we know that there’s biological drivers for people to regain weight after weight loss. So, using these medications to treat a biological disease is not cheating. It’s not taking the easy way out. It’s like taking medication when you’ve got cancer or taking medication when you’ve got high blood pressure. If you need to go on a medication for obesity, you should, and you should do it without any associated stigma or shame or commentary. This biological-based disease has biologically-based treatments”
After decades trying to help people manage the health effects of obesity, Sam sees these drugs like any other drug – a valuable tool to help people live a healthy life.
“I think they’re fantastic, not because they help people lose weight, but because they’re addressing the metabolic dysfunction that often goes along with excess weight.”
Are these medications ever going to get cheaper?
At $200 to $700 a month, GLP-1 medications are just impossible for many people to afford. Help is on the horizon, but it might be a while yet.
Three things might bring the price down: generics coming onto the market, pill-based GLP-1 medications, and subsidies from the government.
The patents for many GLP-1 medications will expire soon, which means that their owners won’t have a monopoly on their manufacture. Generic medications are usually cheaper than name-brand medications, but Sam doesn’t think this will change the price that much.
“I’m not a biochemist, but apparently they’re not technically that hard to make. But they’ve got to be in an injectable delivery device, and they’ve got to be transported with cold chain storage, and that just adds to cost. So even though the prices may come down, I don’t think it’s going to be cheap.”
GLP-1 pills have been developed, and are currently being studied. They might reach Australia by 2027, but it’s still unclear whether they’ll replace injections, be used as maintenance after injectable treatment, work as effectively as the shots, or how much they’ll cost.
Semaglutide (the drug that’s in Ozempic) has been added to the PBS, which will make the cost cheaper – but only for some people.
“The PBAC [Pharmaceutical Benefits Advisory Committee] just made a recommendation to have Semaglutide listed on the Pharmaceutical Benefits Scheme for people who have obesity and established cardiovascular disease” Sam notes.
We’ve never, ever had a positive PBAC recommendation for obesity therapy in this country, in the history of all time. So that’s really, really significant.”
However, this subsidised medication will only be available to people who meet the BMI threshold of obesity and who also have heart disease.
Disclosure: Sam Hocking has served on advisory boards for Novo Nordisk and Lilly, is an investigator on international clinical trials for both companies and has received honoraria for educational lectures from both companies. Details are available on disclosureaustralia.
