Comparisons
Retatrutide is a triple-hormone medicine and eloralintide an amylin medicine, both from Lilly. They sit at different stages, and the evidence for each is reported on its own terms here.
Different mechanisms, same sponsor
Retatrutide acts on three receptors at once: the GIP receptor, the GLP-1 receptor and the glucagon receptor. Eloralintide acts on the amylin pathway only. Lilly is also studying eloralintide together with tirzepatide, a GIP and GLP-1 medicine, but not with retatrutide in anything this site has found. Lilly funds the trials of both, which is worth keeping in mind when reading either.
Different pathways, same sponsor. No trial this site has found has tested the two together.
The retatrutide results
In the Phase II trial (338 adults, 48 weeks), the mean change in body weight was -8.7% at 1 mg, -17.1% at the combined 4 mg groups, -22.8% at the combined 8 mg groups and -24.2% at 12 mg, against -2.1% on placebo. In the Phase III TRIUMPH-1 trial, 2,339 adults without diabetes received retatrutide 4 mg, 9 mg or 12 mg or placebo for 80 weeks. The mean change in body weight was -17.6%, -23.7% and -25.0% against -3.9%, using the treatment-regimen estimand. The most common adverse events were gastrointestinal. The paper also reports separate results in participants with knee osteoarthritis (pain scores) and obstructive sleep apnea (apnea-hypopnea events).
[Verified V-53] From the PubMed abstracts of Jastreboff et al., New England Journal of Medicine: Phase II 2023 (PMID 37366315, DOI 10.1056/NEJMoa2301972) and TRIUMPH-1, published 2026-09-29 (PMID 42814954, DOI 10.1056/NEJMoa2604169), read 2026-10-02. Lilly’s May 2026 topline announcement reported -28.3% at 12 mg (V-22); the peer-reviewed abstract headline is -25.0% under the treatment-regimen estimand. The abstract does not say how the topline figure was derived, so the two are not reconciled here.
Newer retatrutide Phase 3 results
Lilly has since announced two more 80-week Phase 3 trials. They are sponsor results, not yet in a peer-reviewed paper that we found, and they use the efficacy estimand, so they should not be set directly beside the treatment-regimen figures above.
| Trial | Population | Retatrutide, mean weight change | Placebo | Stopped for adverse events |
|---|---|---|---|---|
| TRIUMPH-2 | 1,152 adults with type 2 diabetes and obesity or overweight | 4 mg: -12.7%; 9 mg: -19.1%; 12 mg: -20.8% | -4.0% | 3.8%, 11.6%, 7.7% against 4.9% on placebo |
| TRIUMPH-3 | 1,949 adults with BMI 35 or higher and established cardiovascular disease | 9 mg: -21.6%; 12 mg: -22.6% | -3.2% | 9.8% and 13.5% against 4.8% on placebo |
[P1 sponsor press release] Eli Lilly and Company, 23 July 2026, TRIUMPH-2 (NCT05929079) and TRIUMPH-3 (NCT05882045). Efficacy estimand, 80 weeks. Figures checked against the release on 2026-10-06.
The eloralintide result
In the 48-week Phase II trial, fixed-dose groups had mean body-weight changes from -9.4% at 1 mg to -20.1% at 9 mg, against -0.4% on placebo, in the efficacy analysis that included all randomly assigned participants. Nausea was reported by 11% to 64% of the dose groups against 14% on placebo. Eloralintide’s Phase III program, ENLIGHTEN, is registered with primary completion dates in 2028, and no Phase III result exists.
[Verified V-06, V-08] Figures as already confirmed against the ClinicalTrials.gov results record and the Lancet abstract.
Why the two cannot be ranked
The retatrutide figures at 80 weeks come from a Phase III trial of over two thousand people. The eloralintide figures at 48 weeks come from a Phase II trial of 263. Different phases, lengths, sizes and analyses mean the numbers answer different questions, and no trial has tested the two medicines against each other. A higher number in one trial is not evidence of any difference in effectiveness between the two.
Same conditions, different stage
Both programs have studied or registered work in obesity, knee osteoarthritis pain and obstructive sleep apnea. For retatrutide those results are in the TRIUMPH-1 paper. For eloralintide, the knee pain (ENLIGHTEN-4) and sleep apnea (ENLIGHTEN-3) trials are registered and have no results.
What the evidence does and does not allow
It allows an accurate description of two mechanisms and two programs at different stages. It does not allow a conclusion about which is preferable, and it gives no guidance on using either. Eloralintide is investigational and not approved, and Lilly describes retatrutide as investigational. In its 29 September 2026 announcement Lilly says it plans to submit retatrutide to the FDA in the first quarter of 2027. That is the sponsor’s statement, so check the FDA for the current position.
Related
See the comparison methodology, the obesity research pipeline and the ENLIGHTEN program.
Frequently asked questions
Is eloralintide better than retatrutide?
No trial has tested the two medicines against each other. The retatrutide figures come from a Phase III trial of more than two thousand people over 80 weeks, and the eloralintide figures come from a Phase II trial of 263 people over 48 weeks. Different phases, lengths, sizes and analyses mean the numbers answer different questions, and a higher number in one trial is not evidence of a difference in effectiveness.
How do eloralintide and retatrutide work differently?
Retatrutide acts on three receptors at once: the GIP receptor, the GLP-1 receptor and the glucagon receptor. Eloralintide acts on the amylin pathway only.
What did the retatrutide TRIUMPH-1 trial show?
TRIUMPH-1 gave 2,339 adults without diabetes retatrutide 4 mg, 9 mg or 12 mg, or placebo, for 80 weeks. Mean body weight changed by -17.6%, -23.7% and -25.0%, against -3.9% on placebo, using the treatment-regimen estimand. The most common adverse events were gastrointestinal.
What did the eloralintide Phase II trial show?
In the 48-week Phase II trial (NCT06230523, 263 adults with obesity or overweight and without type 2 diabetes), mean body weight changed by -9.4% in the 1 mg group up to -20.1% in the 9 mg group, against -0.4% on placebo. These are group averages and do not predict any individual result.
Is eloralintide being tested with retatrutide?
Not in anything this site has found. Lilly is studying eloralintide together with tirzepatide, a GIP and GLP-1 medicine, but no registered study we found combines it with retatrutide.