Understanding the link between obesity, AF, and how medications like Ozempic and Mounjaro may help

Introduction

If you’ve landed here, chances are you or someone you know is living with atrial fibrillation (AF) – a common heart rhythm condition that can cause palpitations, breathlessness, and fatigue. One well-established risk factor for AF is obesity, and we now have compelling evidence that weight loss can significantly reduce AF symptoms, or even reverse the condition in some cases.

With the arrival of powerful new weight loss medications like semaglutide (sold as Ozempic or Wegovy) and tirzepatide (Mounjaro), many patients are asking: Could these drugs also help with atrial fibrillation?

Let’s explore what the latest science and clinical experience – suggests.

James’ Story: How Weight Loss Medication Helped His Atrial Fibrillation

I met James about two years ago. At the time, he weighed around 107 kilograms and stood 5 foot 8 inches tall. He had recently developed atrial fibrillation (AF) – and it was making him seriously unwell.

Not only was he experiencing the typical symptoms of AF, but his heart’s pumping efficiency (known as the ejection fraction) had dropped to below 35% – meaning he technically had heart failure caused by his atrial fibrillation. Alongside this, he was consuming around 30 to 40 units of alcohol per week, which certainly wasn’t helping his heart.

Initially, we tried to restore his normal heart rhythm using a cardioversion, but unfortunately, he quickly reverted back into AF. Our next step was an AF ablation procedure, which appeared to go well but once again, his atrial fibrillation returned soon after.

At that point, I have to admit, I was becoming pessimistic about James’ long-term outcome.

But rather than give up, we shifted our focus. I referred him to a specialist weight management clinic to address two key contributors to his AF: his weight and alcohol intake. He was started on Ozempic (semaglutide), to help facilitate weight loss.

As James gradually recovered from the ablation procedure, I performed another cardioversion. This time, his heart rhythm stabilised in normal sinus rhythm. But I knew if he didn’t lose weight, the risk of reverting back into AF remained high.

Fortunately, the Ozempic began to work. When I saw him again nine months later, the transformation was remarkable:

  • He had lost 29 kilograms.
  • His alcohol cravings had reduced significantly.
  • He felt much better in himself.
  • Most importantly, his echocardiogram showed that his heart function had completely returned to normal.

Given how resistant his AF had been to treatment, this was a phenomenal result. In my view, the weight loss facilitated by Ozempic played a key role in helping him maintain normal rhythm and recover his heart health.

James’ experience prompted me to explore what the latest research says about Ozempic, Mounjaro, and their potential role in managing atrial fibrillation – particularly in people where obesity is a major contributing factor.

What Is Atrial Fibrillation (AF)?

Atrial fibrillation is a heart rhythm disorder where the upper chambers of the heart (the atria) beat irregularly and often too fast. This can lead to symptoms such as:

  • A fluttering or pounding heartbeat
  • Shortness of breath
  • Tiredness or reduced ability to exercise

It also increases the risk of stroke and heart failure if left unmanaged.

How Does Obesity Affect Atrial Fibrillation?

Being overweight places strain on your heart. It increases inflammation, contributes to high blood pressure, and is closely linked to obstructive sleep apnoea – all of which can raise your risk of AF.

In fact, studies have shown that weight loss can not only reduce the frequency of AF episodes, but in some cases, help the heart return to a normal rhythm.

One of the most important studies in this area, the LEGACY study from Australia, found that patients with persistent AF who lost more than 10% of their body weight were far more likely to stay in normal rhythm over time. Some reversed AF altogether. LEGACY Study

The Rise of New Weight Loss Medications

Originally developed to treat type 2 diabetes, drugs like semaglutide (Ozempic/Wegovy) and tirzepatide (Mounjaro) are now licensed for the treatment of obesity.  Semaglutide is from a family of drugs known as GLP-1 receptor analogues (GLP-1 RA) which are increasingly used to help people lose weight. Mounjaro has similar properties but also acts on another hormone target (a gastric inhibitory polypeptide, or “GIP” analogue).

 

They work by mimicking gut hormones that:

  • Help regulate appetite
  • Slow down digestion
  • Improve blood sugar control

Clinical trials have shown that people taking these medications can lose between 5% and 15% of their body weight – and with Mounjaro, sometimes even over 20%.

These drugs are increasingly available both on the NHS for selected patients and through private clinics and high-street pharmacies like Boots and Superdrug.

Can These Medications Help With Atrial Fibrillation?

This is an exciting and evolving area of research.

We already know that losing weight reduces AF burden, and these medications are some of the most effective tools for sustained weight loss. But what about their direct effect on AF?

A number of recent studies and meta-analyses have shed new light:

  • A 2024 meta-analysis of 21 RCTs involving over 25,000 patients found that semaglutide was associated with a 30% reduction in AF occurrence compared to control medications (RR 0.70, 95% CI 0.52–0.95). Link to study
  • Another European Heart Journal analysis of 16 trials (nearly 20,000 patients) reported a 46% lower odds of developing new-onset AF in patients using semaglutide (OR 0.54, 95% CI 0.39–0.77). Link to study
  • A 2025 retrospective cohort study on tirzepatide (Mounjaro) found it was linked to a 35% lower risk of AF-related interventions like cardioversion, antiarrhythmic medication, or AF ablation (HR 0.65, 95% CI 0.55–0.76). Link to study
  • An updated meta-analysis in the European Journal of Preventive Cardiology showed semaglutide reduced AF incidence by 17% overall, with the oral formulation cutting risk by 52%. Link to study

While these medications are not yet licensed specifically to treat AF, the growing body of evidence suggests they may reduce the risk of developing AF and lower recurrence rates, particularly in people with obesity and type 2 diabetes.

Are These Drugs Safe for People With Heart Conditions?

Yes – in general, GLP-1 receptor agonists like Ozempic and Mounjaro are safe for people with heart rhythm disorders.

In fact, the SELECT trial showed that semaglutide can reduce major cardiovascular events, even in people who didn’t lose weight – highlighting benefits in reducing cardiovascular risk beyond weight loss alone. Link to study

That said, side effects are common in the first few weeks. Around 10–20% of people may experience:

  • Nausea
  • Bloating
  • Changes in bowel habits

These are usually temporary and can be managed with support from your prescribing clinician.

Who Might Benefit From These Treatments?

These medications may be particularly helpful for:

  • People with AF and obesity who have struggled to lose weight through lifestyle changes alone
  • Those with type 2 diabetes and AF
  • Patients who are keen to reduce their risk of AF recurrence

Every patient is different, and treatment decisions should always be made on a case-by-case basis.

Other Lifestyle Changes That Reduce AF Risk

While weight loss is key, other lifestyle factors can significantly reduce your risk of AF or ease symptoms, and also have a role in cardiovascular disease prevention:

  • Reduce alcohol intake: Randomised clinical trials show this can improve AF burden
  • Treat sleep apnoea: A common but often missed contributor to AF
  • Exercise regularly: Improves overall heart health and lowers recurrence
  • Manage stress and caffeine: Both can be triggers in sensitive individuals

Conclusion: A Weighty Role in Heart Rhythm Health

Weight loss plays a vital role in managing atrial fibrillation – and for many, the newest generation of medications offers a safe and effective way to achieve it.

While we’re still learning about their full potential in treating AF directly, the combination of weight loss, improved cardiovascular health, and emerging evidence makes them a promising tool in the overall management of atrial fibrillation – particularly for patients with obesity.

A Cardiologist’s View: When Should These Medications Be Used?

From my experience, I’m increasingly seeing a role for weight loss medications like Ozempic and Mounjaro much earlier in the treatment of patients with atrial fibrillation, particularly where weight is a major contributing factor.

If a patient has struggled to lose weight with conventional means and is living with AF, I now seriously consider starting one of these medications sooner rather than later. In fact, for anyone with a body mass index (BMI) over 35 — and almost certainly over 40, I’d now view weight loss medication as a primary treatment, rather than a secondary option after procedures like ablation or cardioversion.

Even though these drugs haven’t been directly trialled as treatments for AF itself, the evidence is compelling: weight loss improves your chances of staying in normal rhythm. These medications offer an effective way to achieve that weight loss, which can be difficult through lifestyle changes alone.

Importantly, using these drugs wouldn’t exclude someone from undergoing a cardioversion or ablation. In most cases, I believe they should be used alongside these procedures, helping to maintain normal rhythm long-term.

Overall, the use of GLP-1 RA medications in AF is an area where I expect both my personal experience and the broader medical evidence to continue growing in the years ahead. As that knowledge develops, we may see guidelines and practice evolve further.

For now, in many patients with AF and obesity, weight loss medications offer a promising and essential tool to help manage the condition effectively.

As always, it’s important to speak with a qualified clinician to explore whether these treatments are right for you.

✅ Ready to Take the Next Step?

If you’d like personalised advice about AF and weight loss treatment options, including whether Ozempic or Mounjaro might be right for you, feel free to book a consultation.