Wegovy for Weight Loss: Risks, Benefits, and Ozempic Differences

The weight-loss drug Wegovy is now available in Australia.

Wegovy is administered as a once-weekly injection and is approved specifically for weight management. It's intended to be used in combination with a reduced-energy diet and increased physical activity.

So how does Wegovy work and how much weight can you expect to lose while taking it? And what are the potential risks - and costs - for those who use it?

Let's look at what the science says.

What is Wegovy?

Wegovy is a brand name for the medication semaglutide. Semaglutide is a glucagon-like peptide-1 receptor agonist (GLP-1RA). This means it makes your body's own glucagon-like peptide-1 hormone, called GLP-1 for short, work better.

Normally when you eat, the body releases the GLP-1 hormone which helps signal to your brain that you are full. Semaglutides enhance this effect, leading to a feeling of fullness, even when you haven't eaten.

Another role of GLP-1 is to stimulate the body to produce more insulin, a hormone which helps lower the level of glucose (sugar) in the blood. That's why semaglutides have been used for several years to treat type 2 diabetes.

How does Wegovy differ from Ozempic?

Like Wegovy, Ozempic is a semaglutide. The way Wegovy and Ozempic work in the body are essentially the same. They're made by the same pharmaceutical company, Novo Nordisk.

But there are two differences:

1) They are approved for two different (but related) reasons.

In Australia (and the United States), Ozempic is approved for use to improve blood glucose levels in adults with type 2 diabetes. By managing blood glucose levels effectively, the medication aims to reduce the risk of major complications, such as heart disease.

Wegovy is approved for use alongside diet and exercise for people with a body mass index (BMI) of 30 or greater, or 27 or greater but with other conditions such as high blood pressure.

Wegovy can also be used in people aged 12 years and older. Like Ozempic, Wegovy aims to reduce the risk of future health complications, including heart disease.

2) They are both injected but come in different strengths.

Ozempic is available in pre-loaded single-dose pens with varying dosages of 0.25 mg, 0.5 mg, 1 mg, or 2 mg per injection. The dose can be slowly increased, up to a maximum of 2 mg per week, if needed.

Wegovy is available in prefilled single-dose pens with doses of 0.25 mg, 0.5 mg, 1 mg, 1.7 mg, or 2.4 mg. The treatment starts with a dose of 0.25 mg once weekly for four weeks, after which the dose is gradually increased until reaching a maintenance dose of 2.4 mg weekly.

While it's unknown what the impact of Wegovy's introduction will be on Ozempic's availability, Ozempic is still anticipated to be in low supply for the remainder of 2024.

Is Wegovy effective for weight loss?

Given Wegovy is a semaglutide, there is very strong evidence it can help people lose weight and maintain this weight loss.

A recent study found that over four years, participants taking Wevovy as indicated experienced an average weight loss of 10.2% body weight and a reduction in waist circumference of 7.7cm.

For those who stop taking the medication, analyses have shown that about two-thirds of weight lost is regained.

What are the side effects of Wegovy?

The most common side effects are nausea and vomiting.

However, other serious side effects are also possible because of the whole-of-body impact of the medication. Thyroid tumours and cancer have been detected as a risk in animal studies, yet are rarely seen in human scientific literature.

In the four-year Wegovy trial, 16.6% of participants who received Wegovy (1,461 people) experienced an adverse event that led to them permanently discontinuing their use of the medication. This was higher than the 8.2% of participants (718 people) who received the placebo (with no active ingredient).

Side effects included gastrointestinal disorders (including nausea and vomiting), which affected 10% of people who used Wegovy compared to 2% of people who used the placebo.

Gallbladder-related disorders occurred in 2.8% of people who used Wegovy, and 2.3% of people who received the placebo.

Recently, concerns about suicidal thoughts and behaviours have been raised, after a global analysis reviewed more than 36 million reports of adverse events from semaglutide (Ozempic or Wegovy) since 2000.

There were 107 reports of suicidal thoughts and self-harm among people taking semaglutide, sadly including six actual deaths. When people stopped the medication, 62.5% found the thoughts went away. What we don't know is whether dose, weight loss, or previous mental health status or use of antidepressants had a role to play.

Finally, concerns are growing about the negative effect of semaglutides on our social and emotional connection with food. Anecdotal and scientific evidence suggests people who use semaglutides significantly reduce their daily dietary intake (as anticipated) by skipping meals and avoiding social occasions - not very enjoyable for people and their loved ones.

How can people access Wegovy?

Wegovy is available for purchase at pharmacists with a prescription from a doctor.

But there is a hefty price tag. Wegovy is not currently subsidised through the Pharmaceutical Benefits Scheme, leaving patients to cover the cost. The current cost is estimated at around A$460 per month dose.

If you're considering Wegovy, make an appointment with your doctor for individual advice.

Lauren Ball works for The University of Queensland and receives funding from the National Health and Medical Research Council, Queensland Health and Mater Misericordia. She is a Director of Dietitians Australia, a Director of the Darling Downs and West Moreton Primary Health Network and an Associate Member of the Australian Academy of Health and Medical Sciences.

Emily Burch does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.