Retatrutide results: How much weight can you lose?

In clinical trials, the amount of weight lost depended on the dose, how long treatment was taken for, and the type of patient included in the study.

The strongest results reported so far come from Phase 3 trials. In TRIUMPH-1, people taking retatrutide 12mg lost an average of 28.3% of their starting body weight at 80 weeks.

People taking 9mg lost an average of 25.9%, while those taking 4mg lost an average of 19.0%.

In the published Phase 2 obesity trial, people taking retatrutide 12mg lost an average of 24.2% of their body weight at 48 weeks, compared with 2.1% with placebo.

This means that, based on trial data, some people may lose around one-quarter of their starting body weight with higher-dose retatrutide when used consistently over many months.

The main published Phase 2 obesity study looked at retatrutide in adults with obesity, or overweight with at least one weight-related condition.

At 24 weeks, average weight loss was:

At 48 weeks, average weight loss was:

The study also found that, at 48 weeks, 100% of people taking 12mg lost at least 5% of their body weight, 93% lost at least 10%, and 83% lost at least 15%.

TRIUMPH-1 Phase 3 obesity results

TRIUMPH-1 is one of the most important retatrutide trials because it studied adults with obesity or overweight without diabetes.

At 80 weeks, average weight loss was:

In the 12mg group, 45.3% of participants lost at least 30% of their body weight.

A study extension also found that people with a starting BMI of 35 or above who continued treatment to 104 weeks lost up to an average of 30.3% of their body weight.

TRIUMPH-4 Phase 3 results

TRIUMPH-4 studied people with obesity or overweight and knee osteoarthritis.

At 68 weeks, average weight loss was:

In the 12mg group, 58.6% of participants lost at least 25% of their body weight and 39.4% lost at least 30%.

These results are very promising, but TRIUMPH-4 included people with knee osteoarthritis, so the results may not apply exactly to every person using retatrutide for weight loss.

Retatrutide has produced some of the strongest weight loss results seen in obesity drug trials so far.

In the Phase 3 trials, adults taking retatrutide 12mg lost an average of 28.7% of their body weight after 68 weeks.

Weeks 1-4: Month One

In the first month, weight loss is likely to be gradual. Retatrutide is started at a lower dose so the body can adjust and side effects can be managed.

You are likely to notice:

• Reduced hunger
• Feeling full sooner
• Smaller portion sizes
• Fewer cravings
• Early weight loss

You can expect to lose around 2-5% of your starting weight after one month on retatrutide.

However, major changes on the scales are more likely to build after several weeks or months.

*Estimated figure. Published retatrutide trials have not reported data for this exact time point; this estimate is based on available clinical trial results.

Weeks 5-8: Month Two

By month two, appetite suppression may become more noticeable, especially as the dose is increased. This is when some people may start to see more consistent weight loss.

You may find it easier to eat smaller meals, avoid snacking and stay in a calorie deficit. Side effects such as nausea, bloating, constipation or diarrhoea may also be more noticeable during dose increases.

After two months on retatrutide, you can expect to lose around 4-8% of your starting weight.

*Estimated figure. Published retatrutide trials have not reported data for this exact time point; this estimate is based on available clinical trial results.

Weeks 9-12: Month Three

By month three, weight loss may become more visible. Clothes may feel looser, waist measurements may reduce, and appetite control may feel stronger.

This is also when lifestyle habits become more important. Retatrutide may reduce hunger, but the best results are likely to come when it is combined with a balanced diet, regular movement and enough protein.

After three months on retatrutide, you can expect to lose around 6-10% of your starting weight.

*Estimated figure. Published retatrutide trials have not reported data for this exact time point; this estimate is based on available clinical trial results.

Weeks 13-24: Month Six

By six months, retatrutide results may be significant for people who respond well to treatment.

In earlier Phase 2 data, people taking retatrutide for six months lost up to 17.5% of their body weight at 24 weeks.

Weeks 25-52: One Year

By one year, results may be substantial.

Phase 2 trial data showed average weight loss of up to 24.2% at 48 weeks, while the newer Phase 3 trial data showed 28.7% average weight loss at 68 weeks on the 12mg dose.

This suggests that weight loss may continue to build beyond 12 months for some people.

The average weight loss on retatrutide depends on the dose and trial.

In the published Phase 2 obesity trial, average weight loss at 48 weeks was:

• 17.1% with 4mg
• 22.8% with 8mg
• 24.2% with 12mg
• 2.1% with placebo

In TRIUMPH-1, average weight loss at 80 weeks was:

• 19.0% with 4mg
• 25.9% with 9mg
• 28.3% with 12mg
• 2.2% with placebo

This means the average weight loss seen with higher-dose retatrutide in trials has been around 24–28% over longer treatment periods.

These studies suggest retatrutide is one of the most promising obesity and diabetes treatments currently in development.

From the results so far, it appears as though retatrutide is set to beat Mounjaro in terms of weight loss potential.

Further reading: Retatrutide vs Mounjaro

The main caution is that retatrutide is still investigational. Some of the newer Phase 3 findings are currently based on official company announcements rather than full peer-reviewed journal publications, so they should be viewed as very encouraging but still not the final word.

Retatrutide is expected to start working very quickly, with some people noticing reduced appetite within the first few days.

You are likely to start losing weight within the first month, although the change may not be obvious at this stage.

By around 3 months, weight loss is more likely to become visible. By 6 months, results should be more obvious, with trial data showing up to 17.5% weight loss at 24 weeks.

By around one year, some people may be close to 25% weight loss, with Phase 3 data showing up to 28.7% by week 68.

To get the best results from retatrutide, treatment would need to be combined with healthy long-term habits.

Eat enough protein

Protein helps preserve muscle while losing weight.

Include strength training

Resistance exercise can help protect muscle mass and improve body shape as weight comes down.

Keep portions smaller

Retatrutide may make you feel full sooner, so large or heavy meals may worsen nausea or indigestion.

Stay consistent

The best results are likely to build over time. Missed doses or stopping treatment may reduce progress.

Drink enough water

Hydration can help with constipation, headaches and tiredness.

Prioritise sleep

Poor sleep can increase hunger, cravings and snacking.

Avoid unregulated sellers

Retatrutide is not currently licensed for routine prescribing. It should not be bought from social media sellers, “research chemical” websites or unregulated online suppliers.
Further reading: Where to buy retatrutide

Retatrutide is injected under the skin.
There is currently no good evidence that one injection site gives better weight loss results than another. The best injection site is usually the one that is comfortable, easy to use and suitable for rotation.
Common injection areas for weekly weight loss injections include:

• Abdomen
• Thigh
• Upper arm

You should always follow the instructions given by your prescriber or the official patient information if retatrutide becomes licensed.

Retatrutide has produced some of the strongest weight loss results seen so far in obesity medicine trials.

The published Phase 2 obesity trial showed up to 24.2% average weight loss at 48 weeks.

Newer Phase 3 results showed up to 28.3% average weight loss at 80 weeks in TRIUMPH-1 and 28.7% at 68 weeks in TRIUMPH-4.

However, retatrutide is still investigational. It is not currently approved for routine weight loss treatment, and more full Phase 3 data is still needed before its long-term role and additional benefits are fully understood.