Why diet, exercise and Ozempic all have a role to play in weight loss

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“Many studies show that healthy diets and exercise are often not enough once obesity has developed. Prevention and treatment are not the same. We know that healthy lifestyle habits can help prevent some cancers, for example, but if someone develops cancer, we don’t say they just need good nutrition and exercise, they also need treatment. It’s not either or.”

Science has been trying to nail an effective weight loss drug for almost a century, with mixed results. Amphetamines fell out of favour in the 1970s because of the risk of addiction, while sibutramine, launched in the 1990s to reduce appetite, was withdrawn because of the risk of cardiovascular disease. But while there are prescription drugs for obesity – including orlistat, which helps block the body’s absorption of fat – none work as well as the newcomers, semaglutide and tirzepatide.

Studies have found that people lost around 15 per cent of their weight over 68 weeks with the highest dose of semaglutide, while those on the highest dose of tirzepatide lost 22.5 per cent of their weight after 72 weeks.

What sparked this shift towards better drugs?

“It’s a clearer understanding of the links between the gut and the brain, and the role that gut hormones play in weight and appetite,” Sumithran explains.

More weight loss drugs are in the research phase – including one to help promote muscle development while reducing fat. But those that target gut hormones are the most promising, she says.

How safe are semaglutide and tirzepatide – drugs that may need to be taken lifelong in order to maintain weight?

“Like all new medications, we won’t know until they’ve been in use for a while but they’re similar to drugs that have been safely used to treat type 2 diabetes for 20 years. They also work in a different way to other obesity drugs that have come before,” says Sumithran.

Does weight loss helped by these newer drugs also translate into better health?

“Studies so far have found that semaglutide and a similar drug liraglutide help protect against heart disease and stroke in people with type 2 diabetes,” says Hocking.

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But not everyone is eligible for weight loss drugs.

“You need to have either a BMI of 30 or more, or a BMI of 27, along with a condition related to overweight such as high blood pressure or obstructive sleep apnoea,” she adds. “But these groups represent around one-third of the Australian population – so the cost of putting anti-obesity drugs on the PBS is considered too high. Yet people who need the help of these drugs most are often those
who can least afford them.”

But semaglutide is in short supply. Stocks of the lower dose version, approved for diabetes in Australia, are unavailable in Australia until the end of March. While Wegovy is registered for weight loss in Australia, it’s unclear when it will be available, Sumithran says.

These drugs won’t fix obesity all by themselves. They’re an add-on to healthy diets and exercise – not standalone treatments. We also need other strategies, including a crackdown on marketing the junk food fuelling obesity. And let’s quit braying about willpower too – and try to grasp the complexities of obesity instead.

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