What is weight loss medicine?

Weight loss medicines are medicines that can support you to lose weight or manage your weight. A doctor may prescribe them for people living with overweight or obesity. Some are also used to help manage type 2 diabetes.

Many Australians live with overweight or obesity. An unhealthy body weight can increase the risk of chronic (long-term) health conditions.

Weight loss medicines can be helpful, but body weight is influenced by many different factors. For best results, medicines are usually used alongside lifestyle and behavioural changes. These medicines can support weight loss but are not a cure for obesity.

How does weight loss medicine work?

Different weight loss medicines work in different ways.

Some work by affecting the hormones that control your appetite. By reducing your appetite, you are likely to eat less and lose weight.

Other types of weight loss medicines change how certain brain chemicals work to reduce your appetite. As a result, you may feel less hungry, have fewer cravings and find it easier to eat smaller portions.

There are also weight loss medicines that stop your body from absorbing fat from your diet. This reduces the amount of fat digested and helps to reduce weight gain.

What types of medicines might I be prescribed?

Weight loss medicines can be grouped based on how they work in your body to help you lose weight.

To help decide which weight loss medicine is best for you, your doctor will talk to you about:

• how often you need to take the medicine
• how long you may need treatment
• the cost
• possible side effects
• your medical history and how it may affect your treatment
• your preferences

Glucagon-like peptide-1 (GLP-1) medicines

Glucagon-like peptide‑1 analogues (GLP-1 analogues) act in a similar way to the hormones that your body releases when you eat. This increases the amount of insulin made in your pancreas, which helps you feel less hungry. GLP-1 analogues also slow down how fast your stomach digests food, which can keep you feeling fuller for longer.

There are 2 main types:

• GLP-1 receptor agonists, such as semaglutide and liraglutide
• dual receptor agonists, such as tirzepatide, which act on 2 natural hormones — GLP-1 and glucose-dependent insulinotropic polypeptide (GIP), a hormone that helps control appetite and blood sugar

Some of these medicines are approved in Australia for weight loss, and some are approved to help manage type 2 diabetes.

These medicines are known by their generic (active ingredient) and brand names:

• semaglutide (Ozempic, Wegovy)
  • Ozempic is approved in Australia for type 2 diabetes.
  • Wegovy is approved for chronic weight management.
• tirzepatide (Mounjaro)
  • approved in Australia for type 2 diabetes and chronic weight management.
• liraglutide (Victoza, Saxenda)
  • Victoza is approved for type 2 diabetes.
  • Saxenda is approved for chronic weight management.

Other weight loss medicines

There are other types of weight loss medicines that work in a different manner to GLP-1 medicines. Other approved medicines include:

• phentermine — helps reduce your appetite via your central nervous system (for short-term use only)
• naltrexone and bupropion — help reduce your appetite and cravings via your central nervous system
• orlistat — reduces how much fat your body absorbs from your diet

Some other medicines are not currently approved in Australia for weight loss.

Depending on which medicine your doctor prescribes, you may need to take a tablet multiple times per day or a weekly injection.

Currently, medicines prescribed for weight loss are not covered by Medicare. Speak to your doctor or pharmacist about the costs.

What are the side effects or risks of weight loss medicine?

Like all medicines, weight loss medicines may have side effects.

A common type of side effect when taking weight loss medicine involves your gastrointestinal ('gut' or digestive) system. These may include:

• nausea and vomiting
• bloating
• constipation
• diarrhoea
• abdominal pain
• reflux

Weight control medicines can have other side effects, including:

• insomnia or fatigue
• dry mouth
• kidney stones
• pancreatitis
• glaucoma

Some weight loss medicines change how certain brain chemicals work to reduce appetite. This can affect your mood and may increase your risk of depression. If you notice new or worsening symptoms of depression or thoughts of suicide, speak to your doctor.

Mental health impacts of weight loss medicine

Weight loss medicines help you to rapidly lose weight. In some situations, losing weight can have a positive impact on your mental health. Weight loss can also be associated with a range of potential mental health complications.

As weight loss medicines reduce your appetite, you may no longer enjoy eating. This can impact your mental health by affecting social situations. For some people, it may lead to an eating disorder.

It is important to eat enough food and nutrients each day. Weight loss medicines can reduce your appetite, so you may not feel as hungry. Speak to your doctor or dietitian to make sure you are getting the nutrients your body needs each day.

Weight gain after stopping weight control medicines

Weight loss medicines do not cure obesity. After you stop taking the medicine, it is important to maintain new habits around eating, exercise and lifestyle. With ongoing support and healthy lifestyle habits, you can continue to work towards your long-term health goals.

Precautions when undergoing medical procedures

Some weight loss medicines can slow the speed at which your stomach empties food after you eat. This may mean you need to fast for longer before some medical procedures. Tell your doctor about all the medicines you are taking before having surgery or a procedure.

This is not a complete list of side effects. For more information, talk to your doctor or pharmacist or read the consumer medicine information leaflet in your medicine package.

When should I see my doctor?

You should see your doctor to discuss weight loss options if you are concerned about your weight, or you feel it may be affecting your health.

You should talk to your doctor if you live with overweight or obesity and have another weight-related health condition such as:

• cardiovascular disease
• type 2 diabetes
• metabolic syndrome
• fatty liver disease

If you are currently taking weight loss medicine and are planning a pregnancy, speak to your doctor. It is not safe to use some medicines while you are trying to become pregnant or are breastfeeding. You can also find out more about your medicines by calling Medicines Line on 1300 633 424.

Are there any alternatives to this medicine?

A good way to lose weight is by making lifestyle changes. This includes:

• keeping a balanced diet
• staying physically active
• creating new habits around eating and mealtimes

Many healthcare professionals can help you to make these lifestyle changes, for example a:

• counsellor
• dietitian
• exercise physiologist

Weight loss medicines should always be used together with healthy lifestyle changes.

Resources and support

For more information on lifestyle changes to lose weight, try these resources:

• Dietitians Australia has nutrition information, tips and recipes to help you eat well.
• LiveLighter offers a range of tools and calculators to help you make lifestyle changes to improve your health.
• Eat for Health advises on healthy diets, portion sizes and other tips for losing weight.
• Diabetes Australia has information on health and wellbeing programs in your state or territory to help you prevent chronic conditions, such as type 2 diabetes.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with you 24 hours a day, 7 days a week.

Languages other than English

The Australian Guide to Healthy Eating shows the recommended portions of each food group to eat and is translated into many other languages.

Information for Aboriginal and/or Torres Strait Islander peoples

Check out the Aboriginal and Torres Strait Islander Guide to Healthy Eating for tips to eat healthy and live long.