Retatrutide results: How much weight can you lose?

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.

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.

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.

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.

Phase 2 results

The first major retatrutide obesity study was a Phase 2 trial in adults with obesity, or overweight with a weight-related condition.

At 48 weeks, average weight loss was:

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

These results show that many people on the higher doses lost around one-fifth to nearly one-quarter of their starting body weight in less than a year. The results were strong enough to make retatrutide stand out very early in development.

The response rates were also impressive. By week 48, 83% of people taking 12mg had lost at least 15% of their starting body weight, compared with 2% on placebo.

Phase 3 results

The newer longer weight-loss data come from TRIUMPH-4, a 68-week Phase 3 trial in adults with obesity or overweight plus knee osteoarthritis.

In TRIUMPH-4, average weight loss at 68 weeks reached:

• 26.4% with 9mg
• 28.7% with 12mg
• compared with 2.1% with placebo.

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 suggest that retatrutide may help some people lose more than a quarter of their starting weight over the course of treatment.

One important point is that TRIUMPH-4 included people with knee osteoarthritis, so it is not exactly the same as a broad general-obesity study.

Even so, it provides the strongest longer Phase 3 weight-loss signal available so far.

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

The clinical trial results for retatrutide look impressive. For weight loss, the published Phase 2 obesity study showed up to 24.2% average weight loss at 48 weeks, while the longer Phase 3 trial showed up to 28.7% average weight loss at 68 weeks.

However, retatrutide is still investigational and is not currently licensed for weight loss treatment in the UK. More Phase 3 data is needed before its approved dose, safety profile, long-term results and availability are fully confirmed.