How Much Weight Can You Lose on Retatrutide? Trial-by-Trial Breakdown

8 min read · Published March 26, 2026 · Reviewed by Dr. [Physician Name]

24.2% in Phase 2. 28.7% in Phase 3. Those numbers are everywhere — in news articles, Reddit threads, and health forums across the Philippines. They are real. They come from published clinical trials. But on their own, they tell you very little about what you personally might experience.

This article gives you the full picture: the specific numbers by dose, the differences between trials, what factors push individual results above or below the average, and what the data means for someone evaluating their weight management options today.

Phase 2 Results by Dose (NEJM, 2023)

The Phase 2 trial enrolled 338 adults with obesity (BMI ≥30, or ≥27 with a weight-related condition) without type 2 diabetes. Participants were randomized to different doses for 48 weeks. The results show a steep dose-response curve.

At 1mg weekly: 8.7% average body weight lost. At 4mg: 17.1%. At 8mg: 22.8%. At 12mg — the highest dose tested: 24.2%.

For someone starting at 100kg, the 12mg result means approximately 24kg lost over 48 weeks. That is roughly half a kilogram per week, sustained for nearly a year. The jump from 4mg to 12mg — approximately 7 percentage points — underscores why dose optimization under physician guidance matters. A subtherapeutic dose produces subtherapeutic results.

Phase 3 Results: TRIUMPH-4 (December 2025)

TRIUMPH-4 studied a different and heavier population — 445 adults with obesity AND knee osteoarthritis, average baseline weight 112.7kg (BMI 40.4) — over 68 weeks.

At 9mg: 26.4% average weight loss (approximately 29.1kg / 64.2 lbs). At 12mg: 28.7% (approximately 32.3kg / 71.2 lbs).

The proportion reaching specific thresholds at 12mg: 85.9% lost at least 10% body weight. 74.5% lost at least 15%. 58.6% lost at least 25%. Nearly 6 in 10 participants lost more than a quarter of their body weight.

These are the highest weight loss numbers ever recorded in a Phase 3 trial for any GLP-1 class medication.

For a week-by-week picture of how these results accumulated, see what to expect during retatrutide treatment.

How Retatrutide Stacks Up

Putting the numbers in context against approved treatments:

Semaglutide (Wegovy) produced approximately 14.9% average weight loss at 68 weeks in STEP-1. Tirzepatide (Zepbound) produced 20.2% at 72 weeks in the SURMOUNT-5 head-to-head trial. Retatrutide's 28.7% in TRIUMPH-4 is approximately 8 points above tirzepatide and 14 points above semaglutide.

These are cross-trial comparisons — different populations, timepoints, and designs — but the magnitude of difference is consistent across every data point.

For the semaglutide-specific comparison, see how retatrutide compares to Ozempic. For the tirzepatide comparison, see retatrutide vs tirzepatide.

What Makes Individual Results Vary

Trial averages are population statistics. Where you fall within the distribution depends on several factors.

Starting BMI matters. TRIUMPH-4 participants averaged BMI 40.4 — substantially higher than many prospective patients. Higher baseline weight tends to produce larger absolute losses. Someone with BMI 32 will likely see a different percentage than someone at BMI 45, even on the same dose.

Dose matters — a lot. Phase 2 showed a 15.5-percentage-point spread between 1mg (8.7%) and 12mg (24.2%). The dose your physician selects, and how well you tolerate escalation, directly shapes your outcome.

Duration matters. Weight loss with GLP-1 drugs is progressive over months. The 48-week and 68-week timepoints reflect sustained treatment. Stopping early means stopping the progression.

Lifestyle is part of the equation. All trials included diet and physical activity counseling. Participants who actively engaged outperformed those who relied on medication alone. The drug reduces appetite and improves metabolism — but what you eat and how you move still influence the magnitude.

Individual biology creates variation. Even within the same dose group, some participants lost 35% while others lost 12%. Genetic, hormonal, and metabolic differences produce real variance.

To assess whether your health profile makes you a likely responder, see who is a realistic candidate for retatrutide.

What "Average" Hides

The 28.7% average in TRIUMPH-4 means roughly half the participants lost more and half lost less. The distribution matters for setting expectations.

At the 12mg dose, 85.9% achieved at least 10% weight loss — meaning the overwhelming majority hit clinically meaningful territory. But 14.1% did not reach that threshold. Approximately 1 in 7 had a more modest response.

A physician does not just prescribe the medication. They manage the dose, monitor the response, and adjust the plan based on what is actually happening — which is how you maximize your probability of falling on the favorable side of the distribution.

The Availability Reality

These results come from a drug still in Phase 3 trials. Retatrutide is not approved. Not available. Not prescribable.

The treatment with the strongest available evidence today is tirzepatide — 20.2% average weight loss in a direct head-to-head trial, FDA-approved, Philippine FDA-approved, accessible through licensed physicians right now.

For how the dosing protocol works in practice, see retatrutide dose escalation explained.

This article is for educational purposes only and does not constitute medical advice. All treatments require evaluation and prescription by a licensed physician. Individual results vary. Kora Health does not guarantee specific outcomes.