What are my options for losing weight? Where GLP-1 medicines fit

Which options are for you?

It depends mostly on your BMI and your health. Lifestyle changes are for everyone. Medicines come in at a lower BMI. Procedures and surgery are for much higher weights.

So if your BMI is in the high 20s, the choice is usually between lifestyle changes alone and lifestyle changes plus a medicine. At 170 cm (5 ft 7 in), a BMI of 27 is about 78 kg (172 lb). Surgery usually starts around a BMI of 35 to 40, about 101 to 116 kg (223 to 256 lb) at the same height.^3,9

The product information and the PBS are different things. The product information, approved by the TGA, says who a medicine is for: Wegovy and Mounjaro from a BMI of 30, or 27 with a condition such as high blood pressure.^9,10 The PBS decides what the government subsidises, and no GLP-1 medicine is subsidised for weight. The PBAC has recommended Wegovy for some people with heart disease and a high BMI, but it hadn't been listed by July 2026.^13,39

These are points where you and a doctor can start a conversation, not rules that you must or must not have something. The Australian algorithm also looks at your health, not just your weight.³

How do the options compare?

In trials, surgery led to the most weight loss. GLP-1 medicines came next, but only while people kept taking them. Lifestyle programmes and pills led to less.

The numbers below come from different trials, with different people. So treat them as rough guides. They are not a direct comparison. "Weight lost" is the average share of starting body weight.

Each option in detail. Weight lost is the average share of starting weight.

We don't show prices in Australia. Pharmacies and clinics set their own, and medicine costs repeat every month. Your pharmacist can tell you what a script costs, and your GP and health fund what a procedure costs.

In the medicine trials, the dummy-injection groups lost 2.4% and 3.1%, or about 2–3 kg.^4,5 These are averages, and results vary from person to person. In those trials, about 14 in 100 people on semaglutide and 9 in 100 on tirzepatide lost less than 5% of their weight.^4,5

Can food and activity changes alone help?

Yes, for many people. Structured programmes helped people lose around 6–9% of their weight, and cut their risk of diabetes.

One large trial, Look AHEAD, followed 5,145 adults with type 2 diabetes.¹ The programme set a calorie target and about 3 hours of activity a week, with frequent group and one-to-one sessions.¹ People lost 8.6% of their weight in the first year, against 0.7% with usual care.¹ After about 10 years, they were still 6.0% lighter, against 3.5%.¹

In the US Diabetes Prevention Program, 3,234 people with high blood sugar (prediabetes) took part.²⁵ The lifestyle group lost 5.6 kg (about 12 lb) on average over about 3 years, against 0.1 kg on a dummy pill.²⁵ Their rate of new diabetes was 58% lower: 4.8 cases per 100 people a year, against 11.0.²⁵

Food: how much to cut

The Australian algorithm describes three steps of eating less:³

• Reduced energy diet: about 2,000–4,000 kJ (480–960 Calories) a day less than you need, mostly by eating vegetables, fruit, wholegrains, legumes, lean protein and dairy, and fewer "discretionary" foods like sweets, chips and sugary drinks.
• Low energy diet: 4,200–5,000 kJ (1,000–1,200 Calories) a day in total, with a set meal plan or one or two meal replacements.
• Very low energy diet: under 3,300 kJ (800 Calories) a day using meal-replacement shakes, with at least monthly check-ups. It's often used for up to 12 weeks, and it isn't for everyone: for example not in pregnancy, and with care over 65.

Protein: the part most people miss

When you lose weight, some of it is muscle. Too little protein makes that worse, and a smaller appetite on a GLP-1 medicine makes protein harder to get.²⁷

The same advisory says to pair protein with strength exercise at least 3 times a week, plus at least 150 minutes of moderate activity like brisk walking.²⁷ If you have kidney disease, ask your doctor before raising your protein.

What to put on the plate

The Australian Dietary Guidelines suggest eating a wide variety of foods from five groups every day. You don't need every group at every meal.¹⁶

Activity and support

Activity. Australia's guidelines advise adults aged 18 to 64 to do 150 to 300 minutes of moderate activity a week, like brisk walking, or 75 to 150 minutes of vigorous activity, like running, plus muscle-strengthening activities on at least 2 days.¹⁵ For people on a GLP-1 medicine, the US advisory above suggests strength exercise at least 3 times a week.²⁷ The Australian algorithm says resistance exercise helps protect muscle, and people with joint, heart or lung problems may need a gentler or water-based plan, perhaps with an exercise physiologist.³ Speak to your GP first if you haven't exercised for a while or have a medical condition.

Support. The Australian algorithm treats supervised lifestyle support as part of every plan, including when a medicine is used.³ WHO also says diet and activity programmes may be offered alongside GLP-1 medicines.³⁰

What about pills, and other medicines that lower weight a little?

Before GLP-1s, Australia approved three other medicines for weight. They help a little to a moderate amount. Some diabetes medicines also lower weight a little.³

Orlistat (Xenical) stops about 30% of the fat in your food from being absorbed; it passes out in your poo. Oily spotting, fatty stools and wind are common if you eat more than about 30 g of fat a day. Over time it can lower vitamins A, D, E and K.³ In a 4-year trial, people on orlistat lost 5.8 kg, against 3.0 kg on a dummy pill.²

Phentermine (sold as Duromine, Metermine and others) is an appetite suppressant approved for short-term use, 3 months, alongside diet. It can raise heart rate and blood pressure and cause sleeplessness and a dry mouth, so it isn't for people with heart disease, an irregular heartbeat or uncontrolled blood pressure, or with some antidepressants.³

Naltrexone–bupropion (Contrave) is a combination tablet for weight. In a 56-week trial, people lost 6.1% of their weight, against 1.3% on a dummy pill. Feeling sick and vomiting are the main side effects.^3,33

Metformin is a diabetes medicine, not an approved weight-loss one. In the Diabetes Prevention Program it led to 2.1 kg of loss on average.²⁵ An international PCOS guideline says doctors should consider it for women with PCOS (polycystic ovary syndrome) and a BMI of 25 or more.³¹

SGLT2 inhibitors, such as dapagliflozin, lead to modest weight loss. Across 116 trials, people lost about 1.8 kg more than on a dummy pill.³²

Where do GLP-1 medicines fit?

They lead to more weight loss than pills or lifestyle alone. But they are a long-term treatment, and most of the weight returns if you stop.

Semaglutide (Wegovy) acts like the gut hormone GLP-1.²⁰ Tirzepatide (Mounjaro) acts on GLP-1 and a second gut hormone, GIP.⁵ Guide 2 explains how they work. In every trial below, people also followed a diet and activity plan.^4,5

Average weight lost in each trial. Kilograms are for someone who starts at 90 kg (198 lb).

Only the last trial compared the two medicines directly; the others each tested one medicine against a dummy injection, so don't compare across them.

Checking it's working. The Australian algorithm sets a target of 10–15% weight loss for many people, and says to step up or change the plan if targets aren't met.³ For teenagers on Wegovy, the product information says to stop if BMI hasn't fallen by 5% after 12 weeks on the full dose.⁹

Tablets. We found no GLP-1 tablet approved for weight in Australia as of October 2026. The trial results on this page are for weekly injections.^4,5

What happens when you stop. A year after stopping semaglutide, trial participants had regained about two-thirds of the weight they lost.⁶ In a tirzepatide trial, everyone first took the medicine for 36 weeks and lost about 21% of their weight.³⁷ Then some were switched to dummy injections. Over the next year, their weight went up by 14% of what they weighed at the switch.³⁷ For someone who weighed 85 kg (187 lb) by then, that is about 12 kg (85 × 0.14 = 11.9). Those who stayed on tirzepatide lost a further 5.5% over the same year.³⁷ The Australian algorithm says weight-loss medicines will usually be needed long term.³ Guide 9 covers stopping.

Who pays. No GLP-1 medicine is on the PBS for weight, so for weight you pay the full price on a private script, every month you take it.¹³ Mounjaro's maker turned down the price terms for a PBS listing in 2026.¹⁹ Some private health extras policies pay part of a non-PBS script, within limits; others exclude weight-loss medicines.^18,40 For type 2 diabetes, Ozempic and Trulicity are on the PBS if you meet the criteria, and you pay the PBS co-payment.^17,38 Ask your pharmacist what your script will cost. Guide 6 covers who pays and safe ways to get them.

Who it's for. The product information allows Wegovy and Mounjaro for weight from a BMI of 30, or 27 with a weight-related condition.^9,10 That is a point where you and a doctor can start talking about it. It does not mean you should take one. Guide 4 covers who should and shouldn't take them.

Who is weight-loss surgery for in Australia?

Surgery is for people with a higher BMI, often with a health condition that weight loss could improve. It gives the largest, longest-lasting loss, but it is a major operation.

Australian thresholds

The Australian algorithm quotes the national criteria from 2013 (that guideline has since been rescinded, and a new one wasn't final when we checked). Taking your situation into account, surgery may be considered for adults with:^3,42

• a BMI over 40, or
• a BMI of 35 to 39.9 with health conditions that may improve with weight loss, or
• a BMI of 30 to 34.9 with poorly controlled type 2 diabetes and a higher risk of heart disease.³

For type 2 diabetes, the Australian Diabetes Society backs surgery from a BMI of 40 whatever your sugar control, from 35 if sugar stays high despite treatment, and says to consider it from 30.³ For Asian people, and as recommended for Aboriginal and Torres Strait Islander people, the algorithm moves its BMI groups down by 2.5.³ Newer guidance from US and international surgeons (2022) offers surgery from a BMI of 35, or 27.5 for Asian people.⁸ The algorithm says surgery should be part of care from a team, with long-term follow-up.³

Results

A Swedish study followed over 4,000 people. Gastric bypass led to 32% loss at its peak, and 25% after 10 years.⁷ Gastric banding, which puts a band around the stomach, led to less: 20% and 14%.⁷ People who had surgery were less likely to die during the study than similar people who didn't.⁷

Diabetes. In a US trial, 5 years after surgery, 29 in 100 (bypass) and 23 in 100 (sleeve) had near-normal blood sugar.⁴¹ With medicines alone, it was 5 in 100.⁴¹ In a Finnish trial, about 1 in 4 to 1 in 3 had diabetes in remission at 10 years.²²

Risks

• Death around the time of the operation is rare: between 3 in 10,000 and 2 in 1,000.⁸
• Over 10 years, 16–19 in 100 needed another operation.²²
• Acid damage to the food pipe was found in 31 in 100 after a sleeve, against 7 in 100 after a bypass.²²
• The Australian algorithm says people who have had surgery need long-term follow-up, and GP practices should keep them in regular review.³

Who pays. Ask your GP about public hospital options where you live, and your health fund about what your cover includes.

What are gastric balloons and endoscopic sleeves?

Both are done through the mouth with a camera tube (an endoscope), without cutting the skin.^11,12 Neither removes any part of the stomach.^11,12

Gastric balloon. A balloon is placed in the stomach using the endoscope. In a US trial, it was removed after 6 months.¹¹ People lost 10.2% of their weight by then, against 3.3% with lifestyle alone.¹¹ By 12 months, loss had eased to 7.6%.¹¹ Feeling sick (87 in 100) and vomiting (76 in 100) were common, and 19 in 100 had it taken out early.¹¹ The trial included adults with a BMI of 30 to 40.¹¹

Endoscopic sleeve gastroplasty (ESG) reshapes the stomach from the inside.¹² In a trial at nine US centres, adults with a BMI of about 30 to 40 (class 1 or 2 obesity) took part.¹² They lost 13.6% at 1 year, against 0.8% with lifestyle alone.¹² Serious problems happened in 2 in 100 people.¹²

How do Australian doctors build up care?

There is no single fixed order. The Australian algorithm sets the plan by your BMI, your waist and any weight-related health problems, and diet and activity stay part of every plan.³

Your GP usually leads, and shares care with specialists for people with a higher BMI or health problems. People with a BMI over 40 and complications are best looked after by a specialist team.³ Here is a simple picture of how the options fit:

For example, the algorithm says a very low energy diet can be used before surgery, and medicines can help keep weight off after a diet or prevent regain.³

Questions people ask