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, Professor of Community Health and Wellbeing, The University of Queensland and Emily Burch, Accredited Practising Dietitian and Lecturer, Southern Cross University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

This is the next article in our ‘Light and health’ series, where we look at how light affects our physical and mental health in sometimes surprising ways. Read other articles in the series.

It’s spring and you’ve probably noticed a change in when the Sun rises and sets. But have you also noticed a change in your mood?

We’ve known for a while that light plays a role in our wellbeing. Many of us tend to feel more positive when spring returns.

But for others, big changes in light, such as at the start of spring, can be tough. And for many, bright light at night can be a problem. Here’s what’s going on.

An ancient rhythm of light and mood

In an earlier article in our series, we learned that light shining on the back of the eye sends “timing signals” to the brain and the master clock of the circadian system. This clock coordinates our daily (circadian) rhythms.

“Clock genes” also regulate circadian rhythms. These genes control the timing of when many other genes turn on and off during the 24-hour, light-dark cycle.

But how is this all linked with our mood and mental health?

Circadian rhythms can be disrupted. This can happen if there are problems with how the body clock develops or functions, or if someone is routinely exposed to bright light at night.

When circadian disruption happens, it increases the risk of certain mental disorders. These include bipolar disorder and atypical depression (a type of depression when someone is extra sleepy and has problems with their energy and metabolism).

Light on the brain

Light may also affect circuits in the brain that control mood, as animal studies show.

There’s evidence this happens in humans. A brain-imaging study showed exposure to bright light in the daytime while inside the scanner changed the activity of a brain region involved in mood and alertness.

Another brain-imaging study found a link between daily exposure to sunlight and how the neurotransmitter (or chemical messenger) serotonin binds to receptors in the brain. We see alterations in serotonin binding in several mental disorders, including depression.

What happens when the seasons change?

Light can also affect mood and mental health as the seasons change. During autumn and winter, symptoms such as low mood and fatigue can develop. But often, once spring and summer come round, these symptoms go away. This is called “seasonality” or, when severe, “seasonal affective disorder”.

What is less well known is that for other people, the change to spring and summer (when there is more light) can also come with a change in mood and mental health. Some people experience increases in energy and the drive to be active. This is positive for some but can be seriously destabilising for others. This too is an example of seasonality.

Most people aren’t very seasonal. But for those who are, seasonality has a genetic component. Relatives of people with seasonal affective disorder are more likely to also experience seasonality.

Seasonality is also more common in conditions such as bipolar disorder. For many people with such conditions, the shift into shorter day-lengths during winter can trigger a depressive episode.

Counterintuitively, the longer day-lengths in spring and summer can also destabilise people with bipolar disorder into an “activated” state where energy and activity are in overdrive, and symptoms are harder to manage. So, seasonality can be serious.

Alexis Hutcheon, who experiences seasonality and helped write this article, told us:

[…] the season change is like preparing for battle – I never know what’s coming, and I rarely come out unscathed. I’ve experienced both hypomanic and depressive episodes triggered by the season change, but regardless of whether I’m on the ‘up’ or the ‘down’, the one constant is that I can’t sleep. To manage, I try to stick to a strict routine, tweak medication, maximise my exposure to light, and always stay tuned in to those subtle shifts in mood. It’s a time of heightened awareness and trying to stay one step ahead.

So what’s going on in the brain?

One explanation for what’s going on in the brain when mental health fluctuates with the change in seasons relates to the neurotransmitters serotonin and dopamine.

Serotonin helps regulate mood and is the target of many antidepressants. There is some evidence of seasonal changes in serotonin levels, potentially being lower in winter.

Dopamine is a neurotransmitter involved in reward, motivation and movement, and is also a target of some antidepressants. Levels of dopamine may also change with the seasons.

But the neuroscience of seasonality is a developing area and more research is needed to know what’s going on in the brain.

How about bright light at night?

We know exposure to bright light at night (for instance, if someone is up all night) can disturb someone’s circadian rhythms.

This type of circadian rhythm disturbance is associated with higher rates of symptoms including self-harm, depressive and anxiety symptoms, and lower wellbeing. It is also associated with higher rates of mental disorders, such as major depression, bipolar disorder, psychotic disorders and post-traumatic stress disorder (or PTSD).

Why is this? Bright light at night confuses and destabilises the body clock. It disrupts the rhythmic regulation of mood, cognition, appetite, metabolism and many other mental processes.

But people differ hugely in their sensitivity to light. While still a hypothesis, people who are most sensitive to light may be the most vulnerable to body clock disturbances caused by bright light at night, which then leads to a higher risk of mental health problems.

Where to from here?

Learning about light will help people better manage their mental health conditions.

By encouraging people to better align their lives to the light-dark cycle (to stabilise their body clock) we may also help prevent conditions such as depression and bipolar disorder emerging in the first place.

Healthy light behaviours – avoiding light at night and seeking light during the day – are good for everyone. But they might be especially helpful for people at risk of mental health problems. These include people with a family history of mental health problems or people who are night owls (late sleepers and late risers), who are more at risk of body clock disturbances.

Alexis Hutcheon has lived experience of a mental health condition and helped write this article.

If this article has raised issues for you, or if you’re concerned about someone you know, call Lifeline on 13 11 14.

Jacob Crouse, Research Fellow in Youth Mental Health, Brain and Mind Centre, University of Sydney; Emiliana Tonini, Postdoctoral Research Fellow, Brain and Mind Centre, University of Sydney, and Ian Hickie, Co-Director, Health and Policy, Brain and Mind Centre, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.