Common questions about weight loss medicines

The use of weight loss medicines depends on your body mass index (BMI). BMI is calculated using your height and weight. Learn more about BMI.

• A weight loss medicine may be considered for people with a BMI of 30 or greater if they have tried lifestyle modifications for at least 6 months without successful weight loss.
• Saxenda, Contrave and Duromine may be used for people with a BMI ≥ 27 if they have at least 1 weight related health problem, eg, high glucose levels, high blood pressure, high cholesterol or obstructive sleep apnoea.

If you have diabetes, then the best glucose lowering therapies to help with weight loss are metformin, empagliflozin and dulaglutide. Talk to your health care professional about whether these medications are appropriate for you.

No, all weight loss medicines are not the same. Each works in different ways, has different side effects and the cost may differ too. Your healthcare provider will discuss the various options with you.

Note: These medicines are not subsidised, which means you'll have to pay for them. They vary in price, costing between $100 and $500 per month. Ask your healthcare provider how much they will cost before you start your course. The prices mentioned below give you an idea of the estimated cost as at September 2022.

The effects of weight-loss medicines are not permanent. When they stop taking them, most people will regain weight over time. However, adopting healthy lifestyle habits may help limit weight gain.

Calorie-controlled eating

• It's important to adopt a healthy eating plan, eg, a balanced and nutritious diet that meets your daily energy requirements.
• It's also important that you can maintain the diet long-term, rather than a choosing a fad, or quick fix diet.

Regular exercise

• At least 2.5 hours of moderate intensity physical activity per week should be included in all weight loss plans.
• Exercise also leads to increased muscle mass and fitness, and improved heart health and mental health.
• Perform muscle strengthening activities 2 days of each week.
• Some physical activity is better than none – increasing physical activity of any kind is beneficial.

Different people respond differently to weight loss medicines and your healthcare provider can help you decide whether using weight-loss treatment long-term is suitable for you.

• Once you have started treatment with a weight loss medicine, your healthcare provider will monitor you on a regular basis for side effects and your response to treatment.
• Usually, people who lose weight after 12–16 weeks of treatment continue to lose weight at 1 year and beyond.
• For people who are overweight or obese, a lasting weight loss of 5–10% can have important health benefits, eg, lowering blood pressure, blood glucose and triglyceride levels. If you are not managing to lose enough weight (eg, weight loss <5% at 3–4 months), the medication should be stopped, as the long-term benefits are likely to be outweighed by the risks and costs.

Yes, there are medicines that shouldn't be used for weight loss. These include:

• Laxatives: Laxatives should not be used for weight loss. Any weight lost by using laxatives is short term, due to fluid or water loss. This is harmful as it can lead to serious problems such as dehydration and salt (electrolyte) disturbances, and in some cases dependence.
• Thyroid hormones: Thyroid hormones such as Eltroxin are not appropriate for losing weight unless the weight gain was caused by an underactive thyroid (hypothyroidism). 
• The use of diuretics, chorionic gonadotrophin, or amphetamines is not appropriate for weight reduction.

Evidence that weight loss medicines directly improve fertility is lacking. Being overweight or obese can reduce fertility in men and women.

• In women being overweight or obese impacts fertility by causing hormonal imbalances, problems with ovulation and period problems. Obesity is also associated with PCOS, a common cause of low fertility or infertility.
• In men, fertility may be reduced by being overweight or obese leading to hormonal imbalances, issues with sperm quality and erection problems.

Overall, even a small weight loss can improve fertility and pregnancy health. You have a greater chance of getting pregnant and having a healthy baby if you are close to a healthy weight. Weight loss in men who are overweight or obese can improve total sperm count and quality.

Note: Weight loss medications are generally unsafe to take during pregnancy, so family planning should be discussed with your prescriber.