The truth about weight-loss drugs with Professor John Wentworth

Glucagon-like peptide-1 (GLP-1) receptor agonist medications, better known as Ozempic, Wegovy or Mounjaro, are rapidly gaining popularity worldwide. Once prescribed primarily for type 2 diabetes, they’re now being embraced for weight loss by everyday Australians and high-profile figures alike.

At a time when obesity remains one of the most significant challenges to public health, these drugs are transformative. Reports of substantial weight loss and improved metabolic health have fuelled enormous interest. But are they truly a universal solution, or is the reality more complex?

SVI’s Professor John Wentworth, endocrinologist and Senior Clinical Research Fellow in Immunology & Diabetes, examines the science behind the headlines, weighing the theories against the real clinical evidence.

Why are these weight loss medications suddenly so popular? 

GLP-1 medications have actually been around for about 20 years, originally created for type 2 diabetes. It was about 10 years ago that they were first approved to treat obesity, and different iterations since then have exploded in popularity as their cost-effectiveness has improved.

And the fact that we have celebrities who are accessing these drugs and social media to proliferate messaging about them creates quite strong demand in the general population.

What do these drugs actually do? 

These medications cause weight loss primarily by suppressing appetite. They act on the brain to reduce ‘food noise’ and stomach to delay its ability to empty food into the intestine, giving a sense of fullness that helps decrease portion size. They also help the pancreas make more insulin, which improves glucose control. And all of this really helps improve blood glucose and blood pressure in overweight people.

On top of this, these drugs also act on the heart and the kidneys. It is suspected that they prevent heart attacks and preserve kidney function due to their direct action on these organs.

So they’re not just helping people manage their weight – for some people, especially those with type 2 diabetes, they are proven to prevent death and organ failure.

But we still don’t truly understand exactly how they work, and more research is needed to get a clearer picture of their benefits.

About two thirds of Australians are considered overweight. Doesn’t that mean that most Australians should be taking these drugs? 

It’s possible that these drugs will benefit many overweight people, but if we’re just talking about fat loss, medications should never be the first line of defence. We have to remember that medications cost money and also come with risks and side effects. In general, it’s important to exhaust other options first, like lifestyle modifications, before considering these interventions. Some people will develop side effects that much outweigh the benefits of the medication.

Prescription of GLP-1s needs to occur on a case-by-case basis, with individual risk factors considered. They’re tremendously helpful for overweight people at high risk of type 2 diabetes who haven’t had success with other approaches, but we’re not about to put it in our tap water. We have to remember that most drugs are not for most people.

I’d like to lose a bit of weight, but I don’t have type 2 diabetes. Could I access these medications? 

Potentially, yes. If you’re carrying excess weight and your clinician decides that you’re at risk of developing type 2 diabetes or other complications, they may conclude that a GLP-1 medication will serve as an effective preventative intervention. Again, it really depends on the individual – we can’t paint these things with a broad brush.

I’ve heard that these medications might have additional benefits, against other addictions and conditions like dementia, for example. Is that true? 

Large population studies and early clinical research are providing growing, evidence-based support for the idea that GLP1 drugs may have benefits beyond weight loss. Two areas receiving intense research attention at the moment are addiction and dementia/neurodegeneration. In relation to addiction, it’s thought that GLP-1s don’t just silence food noise: there’s growing evidence that they can reduce cravings for substances like alcohol, nicotine and even illicit drugs. But, we’re not exactly sure how or why they have this effect.

It’s a fast-moving field. There are multiple clinical trials taking place right now, which will give better clarity on the possible additional benefits of GLP-1s. Watch this space!

Professor John Wentworth is a Senior Clinical Research Fellow in SVI’s Immunology & Diabetes Unit and an endocrinologist at the Royal Melbourne Hospital.