‘There’s a real bias’: what do we know about anti-obesity drugs in Australia?

Dr Kathryn Williams has had patients cry when they go on anti-obesity drugs. "[They] say, 'oh my god, this is the first time I haven't felt hungry'," says Williams, an endocrinologist at the University of Sydney, "because hunger is just something they have to live with every single day."

Shows like The Biggest Loser perpetuated the idea that with radical enough lifestyle change and exercise, anyone can lose weight. But like so much reality television, it's a far cry from reality. "This whole thing where we think everyone's equal and it's about choice is just a complete lie," Williams says. "We still need to understand that there are some people that have biological reasons as to why they gain weight and those people need treatment."

Anti-obesity drugs are not new. They've been available in Australia for the treatment of either obesity or type 2 diabetes as early as 2000. However these medications have attracted headlines recently thanks to their popularity among celebrities and influencers, and a shortage of one particular product - semaglutide, marketed in Australia as Ozempic and approved only for the treatment of type 2 diabetes - possibly due to its popularity with celebrities and influencers. The drug has become so widely known in popular culture that it was the subject of jokes at the recent Oscars.

Last May, the Therapeutic Goods Administration reminded GPs not to prescribe Ozempic to people without type 2 diabetes in the face of a global shortage of the drug due to surge in demand for it as a weight loss aid. In January, the TGA indicated it expected supply to be returning around this month. It also announced it was investigating TikTok and other influencers for promoting the drug as a weight loss tool.

Given the high profile of semaglutide - for example, being branded the Hollywood 'skinny jab' - there are concerns that it is being used by people who don't meet the clinical criteria for overweight or obesity. But it is unclear whether there is underground use in Australia.

"All that reporting about the Hollywood skinny jab and about people using it to just lose a couple of kilos; if that is happening, I don't know where those people are getting a medical practitioner to prescribe them that medication," says Associate Prof Priya Sumithran, head of obesity medicine at Austin Health, and researcher at Monash University.

For people with obesity, the majority of whom will undertake a difficult, uncomfortable and often unsuccessful journey to manage their weight solely through diet and exercise, or for those reliant on these drugs to manage their type 2 diabetes (which impacts nearly 1.3 million Australians), these medications can be not only life-changing but life-saving.

"Although many people can successfully lose weight, for most people they regain the weight they've lost, and then the amount of weight that they keep off long-term is actually very, very modest," says endocrinologist Associate Prof Samantha Hocking, from the Charles Perkins Centre at the University of Sydney.

The reason is metabolic adaptation: when people with overweight or obesity try to lose weight, their body fights back hard to keep it. Their metabolic rate slows down, so they become more efficient at using energy. The hormones that regulate appetite increase in the case of the so-called "hunger hormone" ghrelin, or decrease in the case of the hormones that make them feel full. And all this takes place in a society saturated with cheap, high-fat, high-energy food.

"If you're living in that environment, you're trying to lose weight, you're more efficient at using energy, your hormones are telling you you're hungry, all that food is available, it's just really easy to slip back," Hocking says. "It's a struggle for people and that's why we do need these highly effective therapies particularly for people who have both obesity and health issues."

The anti-obesity drugs available in Australia today - some of which are approved for the treatment of obesity, others for the treatment of type 2 diabetes - work in a variety of ways.

The oldest, orlistat - marketed in Australia as Xenical - is the only one that acts in the gut itself, to block the absorption of dietary fat. Phentermine, which is sold under a number of different brands, is an appetite suppressant that stimulates the release of certain neurotransmitters that make people feel full.

Liraglutide, sold as Saxenda, and semaglutide, sold as Ozempic and Wegovy in Australia, are both glucagon-like peptide-1 (GLP-1) receptor agonists, which means they act in the same way as a naturally occurring hormone that reduces appetite. And finally there's a combination treatment called Contrave containing naltrexone and bupropion, both of which are used to manage cravings, for example, in smokers and people with drug or alcohol addiction.

Conversations and understanding about obesity have developed over time, alongside concerns about the condition as a public health issue. Some advocates and researchers note that people can be metabolically healthy while living with obesity. The idea that obesity can and must be simply fixed, some argue, may perpetuate the shame and discrimination people with obesity can live with.

In Australia, these drugs are only approved for use in people with obesity - defined as a body mass index (BMI) of 30kg/m2 - or in those with a BMI of 27 or above and with at least one weight related health issue such as type 2 diabetes or high blood pressure. In the case of Ozempic, it's only authorised for the treatment of type 2 diabetes. But all are required to be used - and only shown to be effective - alongside diet and lifestyle changes.

"Medications and surgery help because they help people make lifestyle changes," says endocrinologist Dr Sumithran. "They're not used instead of lifestyle, they are used as an additional treatment."

She says her patients who respond to the drugs find it much easier to stick to those lifestyle changes because the treatment reduces their hunger. "The amount of mental effort and thought that goes into having to stick to that is less when you've got a medication that is stopping a lot of that hungry chatter in your mind," says Sumithran.

Like blood pressure or cholesterol tablets, these are drugs patients remain on for life. Evidence shows that once the medication is ceased, the weight returns.

The evidence from industry funded clinical trials suggest that these medications are effective and have relatively minor side-effects. One recent trial of semaglutide combined with a low-calorie diet and exercise for adults with overweight or obesity saw weight loss of up to 16% body weight at one year, compared to 5.7% in the placebo group.

The most common side-effects of Ozempic include nausea, diarrhoea, constipation and vomiting. Some users describe missing eating and the pleasure of food.

Dr Georgia Rigas, a Sydney GP who specialises in weight loss therapies, says if anything, obesity medications are underused in Australia. "Only a minority of people who potentially could benefit from therapy are actually seeing their doctor, getting a script and taking the medication," says Rigas. It's a similar case for bariatric surgery.

She says one of the reasons is fat-shaming, discrimination and weight stigma. Australia's Obesity Collective last year raised concerns that discourse about the Ozempic shortage sometimes apportioned blame to people with obesity taking the drug as prescribed by their doctor managing their chronic condition. Rigas' own research suggests that it takes on average nine years from the point at which a person with obesity starts to worry about their weight until they actually see a healthcare professional about it.

"I can't think of any other health condition where a person feels that they need to 'do it on their own', and not seek help sooner rather than later," Rigas says. Many of the people in the study felt that their obesity was their responsibility, that it was self-inflicted, and "so why would I go to ask for help?".

But physical and psychological harm can happen in that long period of time before they do get help, whether it's wear and tear on joints, infertility, diabetes, arthritis, or bullying and low self-esteem.

Another reason these drugs are underused is cost. "Despite two-thirds of Australian adults living with overweight or obesity, there's no medication on the PBS [Pharmaceutical Benefits Scheme]," Rigas says. Anyone prescribed an anti-obesity medication can expect to pay up to $380 or so a month, depending on the treatment, unless they can get reimbursement from their private health fund. And that's a huge equity issue.

"The prevalence of obesity is highest in lower socioeconomic areas, regional and remote areas," Rigas says. "So people who are least likely to have health insurance are the ones that are suffering the most and less likely to actually get the treatment that they need and they deserve."

Most recently, the government's Pharmaceutical Benefits Advisory Committee, which makes recommendations about which drugs to subsidise, knocked back an application for Wegovy (semaglutide) for treatment of obesity to be added to the PBS. While approved for use for people with obesity, the committee argued that the predicted benefits were too uncertain for the potentially high cost of subsidising the drug. They noted the "lack of long-term data beyond two years and the potential for rebound following discontinuation of treatment".

They also highlighted the risk of the drug being used outside any restrictions placed on its use.

"There's a real bias, a stigma about obesity and a bias against using effective treatments for obesity," Sumithran. She stresses that taking these medications is not an 'easy way out', and that people taking them still have to work hard to manage their lifestyle alongside the treatments.

"The fact that people regain weight is not because they haven't put in effort or they're not trying hard enough," she says. "The environment that we live in is not helping us."