Long term medical management is vital for managing obesity, an often-stigmatised condition that is complex and chronic.

A Narrative review published online first in The Medical Journal of Australia explores current and emerging medications for the management of obesity in adults. 

Obesity is the second leading contributor to Australia’s burden of disease due to complications of cardiovascular disease, type 2 diabetes, kidney and liver disease, obstructive sleep apnoea, and several cancers.

The review was authored by University of Melbourne Associate Professor Priya Sumithran, an endocrinologist, and PHD student Rosalind Walmsley.

It states that the health complications that can accompany obesity can be prevented or mitigated by weight loss of as little as 5%.

“Lifestyle interventions that incorporate reduction in energy intake, improved diet quality and increased physical activity are the foundation of obesity management,” they wrote.

“However, obesity is chronic and relapsing, and most people who lose weight with lifestyle interventions alone will regain weight over time.”

Commenting on the review for InSight+, Sydney endocrinologist Dr Namson Lau said he had seen the benefits of medications for obesity management in his own practice.

“Many patients who have high range obesity or those with obesity-related complications find it challenging to achieve and maintain clinically significant weight loss despite adherence to lifestyle measures,” Dr Lau said.

“For these people, medical therapy can be an important adjunct to help them reach and sustain weight loss, improve their obesity-related comorbidities and reduce their long term risk for cardiovascular diseases.”

There are five medications approved by the Therapeutic Goods Administration for obesity management in Australia, including semaglutaide, better known as Ozempic.

There have been considerable advances in obesity pharmacotherapies in the past decade as medical understanding of the pathophysiology of obesity grows (here and here).

Currently, there are five medications approved by the Therapeutic Goods Administration (TGA) for obesity management in Australia.

Several more are currently under development as treatment modalities evolve, including a combination of cagrilintide and semaglutide.

The current available medications are:

  • orlistat, which reduces absorption of dietary fats by preventing their digestions and increasing the excretion;
  • phentermine, which releases noradrenaline, dopamine and serotonin to reduce hunger and reward-related eating;
  • naltrexone–bupropion, which combines the antidepressant bupropion with opioid antagonist naltrexone to affect the central appetite and reward regions of the brain;
  • glucagon-like peptide 1 (GLP-1) receptor agonists, which reduce food intake by acting on GLP-1 appetite and reward regions of the brain — these include semaglutide, which has been in the news under the name Ozempic (Novo Nordisk) due its use by celebrities and influencers and the consequential supply shortages for people who require the medication to manage type 2 diabetes; and
  • topiramate, which is a carbonic anhydrase inhibitor used in the treatment of epilepsy and migraines; it is not approved by the TGA for obesity management but is commonly used off-label for this purpose.

Associate Professor Sumithran and Ms Walmsley wrote that individual responses to medications vary, with 25–69% of participants achieving at least 10% weight loss over one year.

The newest medications, and those currently in clinical development, demonstrated greater results than other older agents, they wrote.

Side effects vary across the medications, but often include nausea, diarrhoea, constipation and insomnia. Contraindications such as hypertension, thyroid conditions and pregnancy must also be considered when prescribing these medications, they wrote.

Associate Professor Sumithran and Ms Walmsley make it clear that these medications are meant for long term management of chronic disease and are not intended for casual use as touted by social media influencers.

Medications for obesity are only effective while in use (here and here), meaning long term adherence is required to maintain weight loss and health benefits.

In commenting on the safety of obesity medications, Dr Lau said there are limited data on the long term safety and clinical outcomes of obesity medications (here and here).

“It’s worth highlighting that once [treatment with] GLP-1 receptor antagonists cease, weight regain is almost certain,” Dr Lau said.

“Prescriptions of these therapeutics, including Ozempic, work best when combined with changes to diet, levels of physical activity and appropriate behavioural change, often achieved through the support of a multidisciplinary clinical team.”

Dr Lau wrote about the Ozempic shortage in an exclusive article for InSight+ this week.

Obesity medications continue to be underutilised despite the advancements being made.

Associate Professor Sumithran and Ms Walmsley wrote that people with obesity often face stigma, even in the health care sector, due to long-standing misconceptions that obesity is caused simply by lifestyle choices and lack of motivation.

This can lead to a reluctance of people with obesity to seek medical treatment and can compromise the quality of the treatment they receive.

Dr Lau said more needs to be done to combat the stigmas associated with obesity and its treatment.

“The [narrative review] serves as a reminder of why the idea that people with obesity just need to try harder in order to lose weight is a fallacy,” Dr Lau said.

“There are many physiological systems designed to defend body weight. These obesity medical therapies target different parts of this defence system.”

Dr Lau said people with obesity should be properly informed and supported by medical professionals when it comes to considering options for weight loss management.

“It is important to discuss weight management in a way that does not only focus on negative imagery or long term risks of harm,” said Dr Lau, “but also in a way that helps individuals understand the complexity of the condition … this is a long term process and their clinical team can support them through the many vagaries of this journey.”

Read the full Narrative Review.

Read more from Dr Namson Lau and his experience with Ozempic shortages.

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