Retatrutide Before and After: Clinical Trial Results and What to Expect

Results snapshot

• Phase 2 trial: 24.2% average body weight loss at 48 weeks on the 12 mg dose (about 58 lbs)
• Phase 3 TRIUMPH-4: 28.7% average body weight loss at 68 weeks (about 71 lbs)
• 100% of participants on 8 mg and 12 mg lost at least 5% of body weight
• 83% on 12 mg lost 15% or more, a threshold associated with significant metabolic improvement
• Weight loss curves had not fully plateaued at end of study

These are clinical trial averages, not testimonials. Retatrutide is still an investigational drug with no FDA approval, which means there are no published patient before-and-after photos from approved treatment. What we do have is detailed data from two major trials showing what participants experienced at each stage of treatment.

The numbers are the strongest reported for any weight loss medication to date. But numbers without context don’t tell you much. Here’s a week-by-week breakdown of what the data actually shows.

What to expect: timeline by phase

Weeks 1-4: the starting dose (2 mg)

During the first month, participants begin at 2 mg weekly. The primary changes in this period are [1]:

• Reduced appetite, often noticeable within the first 1-2 weeks
• Modest weight loss: approximately 2-3% of body weight
• GI adjustment period: mild nausea in some participants, though the low starting dose minimizes this
• No dramatic visible changes yet

At 2 mg, the triple-receptor activation is at its lowest therapeutic level. The body is beginning to adjust to GLP-1-mediated appetite suppression and glucagon-driven metabolic shifts. For most people, this phase feels like a gradual decrease in hunger and portion sizes.

Weeks 5-12: dose escalation (4 mg → 8 mg)

This is when weight loss accelerates. The dose doubles at week 5 (to 4 mg) and again at week 9 (to 8 mg) [1]:

• Weight loss at 12 weeks: approximately 8-12% of starting body weight
• Appetite suppression becomes more pronounced
• Some participants report changes in food preferences (less interest in high-calorie foods)
• GI side effects are most common during this period, particularly after each dose increase
• Early visible changes: clothes fitting differently, face appearing thinner

By week 12, participants in the 12 mg group had already lost roughly 12-14% of their body weight in the phase 2 trial. For someone starting at 240 pounds, that’s about 30 pounds [1].

The side effects during this phase are real. Nausea affected up to 60% of participants at higher doses, though most cases were mild to moderate. The gradual dose escalation protocol is specifically designed to minimize GI impact during these weeks.

Weeks 13-24: maintenance dose and acceleration

Once at the 12 mg maintenance dose, weight loss continues at a steady pace [1]:

• 24-week results (phase 2): -17.5% body weight on 12 mg (about 42 lbs for a 240-lb starting weight)
• GI side effects generally improve as the body adapts to the maintenance dose
• Metabolic markers begin to improve: fasting glucose, insulin levels, blood pressure
• 72% of participants with prediabetes at baseline reverted to normoglycemia
• Visible changes are noticeable to others at this point

The 24-week mark was the primary endpoint of the phase 2 trial. At this point, the weight loss on retatrutide 12 mg (-17.5%) already exceeded the typical maximum weight loss seen with semaglutide at any timepoint (~15-17%) [1].

Weeks 24-48: continued weight loss

Weight loss did not plateau at 24 weeks. The curves continued downward through 48 weeks [1]:

48-week results by dose:

Dose	Total weight loss	Avg. pounds lost (240 lb start)
4 mg	-17.1%	~41 lbs
8 mg	-22.8%	~55 lbs
12 mg	-24.2%	~58 lbs
Placebo	-2.1%	~5 lbs

Response rates at 48 weeks (12 mg):

• 100% lost ≥5% of body weight
• 93% lost ≥10%
• 83% lost ≥15%

The near-universal response rates are noteworthy. With semaglutide, roughly 86% of participants lose ≥5% and 69% lose ≥10%. With tirzepatide, about 91% lose ≥5% and 79% lose ≥10%. Retatrutide’s response rates are the highest published for any weight loss medication [1, 2].

Weeks 48-68: phase 3 extended data

TRIUMPH-4 ran 20 weeks longer than the phase 2 trial and produced even larger weight loss [3]:

• 68-week results (12 mg): -28.7% body weight
• Average absolute weight loss: approximately 71.2 pounds
• Placebo-adjusted weight loss: 26.6%
• Weight loss curves still appeared to be trending downward at 68 weeks
• 75% reduction in knee osteoarthritis pain

For someone starting at 250 pounds, a 28.7% loss means reaching approximately 178 pounds. That magnitude of weight change is typically associated with dramatic improvements in quality of life, mobility, metabolic health markers, and cardiovascular risk factors.

Beyond weight: other measurable changes

Weight on a scale is the most reported outcome, but clinical trials measured several other changes [1, 3]:

Metabolic improvements

• Fasting glucose levels decreased significantly across all dose groups
• 72% of participants with prediabetes reverted to normal blood sugar levels
• Insulin sensitivity improved in a dose-dependent manner
• HbA1c reductions were observed even in participants without diabetes

Liver fat

In the separate MASLD trial, retatrutide reduced liver fat by up to 82%, with 86% of 12 mg participants reaching normal liver fat levels (below 5%) at 24 weeks [4]. This is a direct effect of glucagon receptor activation increasing hepatic fat oxidation.

Cardiovascular markers

The TRIUMPH-4 trial reported reductions in blood pressure and cardiovascular risk factors, though detailed data hasn’t been published yet. The phase 2 trial showed modest heart rate increases that peaked at 24 weeks and declined afterward [1, 3].

Joint pain

In TRIUMPH-4, participants with knee osteoarthritis experienced a 75% reduction in pain. While some of this is attributable to weight loss reducing mechanical stress on joints, it suggests additional anti-inflammatory effects [3].

Factors that affect results

Clinical trial averages don’t predict individual outcomes. Several factors influence how much weight a person loses on retatrutide [1]:

Starting weight and BMI. Participants with higher starting BMI tended to lose more absolute weight but similar percentages. The 24.2% average was across a population with BMI ≥30.

Dose level. The difference between 4 mg (-17.1%) and 12 mg (-24.2%) is significant. Dose selection directly affects outcomes, though so does tolerability.

Diet and exercise. Trial participants received standard lifestyle counseling. Those who maintained healthier eating patterns and physical activity likely performed better, though the trial didn’t stratify results by adherence to lifestyle changes.

Individual variation. Even within dose groups, there was a range of outcomes. Some participants lost substantially more than the average, while others lost less. Genetics, gut microbiome, hormonal status, and medication adherence all play roles.

Treatment duration. Weight loss had not plateaued at 48 weeks (phase 2) or 68 weeks (phase 3). Longer treatment likely produces greater results, though the rate of loss slows over time.

What we don’t know yet

There are no published before-and-after photos from FDA-approved retatrutide treatment because the drug isn’t approved. The data above comes entirely from controlled clinical trials. A few things the data doesn’t tell us [1, 3]:

• Long-term weight maintenance. What happens after 68 weeks? Does weight loss continue? Plateau? The trials haven’t run long enough to answer this.
• Weight regain after stopping. Data from semaglutide and tirzepatide shows significant weight regain after discontinuation. Retatrutide likely follows the same pattern, but no data exists yet.
• Real-world results. Clinical trial participants receive regular monitoring, follow-up, and lifestyle counseling. Real-world results may differ.
• Body composition details. How much of the weight lost is fat versus lean mass? Some GLP-1 medications cause concerning levels of muscle loss. Retatrutide data on body composition hasn’t been published in detail.

For guidance on preserving muscle during weight loss treatment, see our guide on Ozempic muscle loss.

Frequently asked questions

How much weight will I lose on retatrutide?▼

The phase 2 trial average on 12 mg was 24.2% at 48 weeks, and phase 3 showed 28.7% at 68 weeks. Individual results vary based on dose, starting weight, diet, and exercise. Not everyone will match the trial averages, and some will exceed them [1, 3].

When will I start seeing results?▼

Most participants noticed reduced appetite within the first 1-2 weeks. Measurable weight loss typically begins by week 2-4. Visible changes that others notice usually appear around weeks 8-12, depending on starting weight [1].

How does retatrutide compare to Ozempic for weight loss?▼

Retatrutide produced roughly 24-29% weight loss compared to semaglutide’s 15-17% in clinical trials. That’s a meaningful difference, but semaglutide is FDA-approved with years of safety data, while retatrutide is still investigational [1, 2]. See also our guide on peptides for weight loss.

Are there before-and-after photos for retatrutide?▼

No verified before-and-after photos exist from FDA-approved retatrutide treatment because the drug is not yet approved. Any transformation photos circulating online would be from off-label use and cannot be verified. The clinical trial data provides the most reliable picture of expected results [1, 3].

Does the weight come back after stopping retatrutide?▼

This data hasn’t been published yet for retatrutide specifically. Based on data from other GLP-1 medications, approximately two-thirds of lost weight is typically regained within one year of stopping treatment. This reinforces that these medications work best as long-term therapy, not short courses [5].

Can I take retatrutide with other weight loss medications?▼

Retatrutide was studied as a standalone therapy in its clinical trials. Combining it with other GLP-1 medications, appetite suppressants, or peptide stacks has not been studied and could increase side effect risk. Any combination therapy should only be done under direct medical supervision.

How does retatrutide weight loss compare to bariatric surgery?▼

Roux-en-Y gastric bypass produces approximately 25-30% body weight loss at 1-2 years. Retatrutide’s 28.7% at 68 weeks is approaching surgical outcomes, though long-term durability data isn’t available yet. Surgery involves operative risk but may produce more durable weight loss without ongoing medication [3, 6].

References

1. Jastreboff AM, Kaplan LM, Frías JP, et al. Triple-hormone-receptor agonist retatrutide for obesity — a phase 2 trial. N Engl J Med. 2023;389(6):514-526. doi:10.1056/NEJMoa2301972
2. Wilding JPH, Batterham RL, Calanna S, et al. Once-weekly semaglutide in adults with overweight or obesity. N Engl J Med. 2021;384(11):989-1002.
3. Eli Lilly. Lilly’s triple agonist, retatrutide, delivered weight loss of up to an average of 71.2 lbs in first successful Phase 3 trial. Press release. December 11, 2025.
4. Sanyal AJ, Kaplan LM, Frias JP, et al. Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial. Nat Med. 2024;30:2037-2048.
5. Wilding JPH, Batterham RL, Davies M, et al. Weight regain and cardiometabolic effects after withdrawal of semaglutide. Diabetes Obes Metab. 2022;24(8):1553-1564.
6. Arterburn DE, Telem DA, Kushner RF, Courcoulas AP. Benefits and risks of bariatric surgery in adults. JAMA. 2020;324(9):879-887.