Retatrutide (Reta) Week by Week: Results Timeline, Week 1 to 80

How long does retatrutide take to work?

Retatrutide, usually shortened to “reta” online, starts reducing appetite in the first week. In trials, participants on the 12 mg regimen had lost about 2-3% of body weight by week 4, 8-10% by week 12, about 17.5% by week 24, 24.2% at 48 weeks and 28.3% at 80 weeks. Full dose is not reached until week 17, so the early weeks understate the eventual result.

Everything below comes from group means in controlled trials: the Phase 2 obesity trial (Jastreboff et al., NEJM 2023), and the Phase 3 TRIUMPH-4 (68 weeks), TRIUMPH-1 (80 weeks), TRIUMPH-2 and TRIUMPH-3 (80 weeks) and TRANSCEND-T2D-1 (40 weeks) readouts. Individual responses vary widely, and no trial reported results for every single week; the per-week figures are interpolated between measured time points and marked as such.

Where should I be at my week?

Enter your start weight and current week to see the trial group mean for that week and the next twelve. Trial means only; it cannot tell you what an unverified product will do.

Start weight

lbkg

Current week Regimen 12 mg target (TRIUMPH-1 curve) 9 mg target 4 mg target 12 mg with type 2 diabetes Show my week

Week	Dose (12 mg schedule)	Trial mean	Weight at the mean	Typical spread*

*Trial means are from the Phase 2 (NEJM 2023) and TRIUMPH-1/-2 (2026) group results on this page, interpolated between measured weeks. The spread column assumes individuals land between 60% and 130% of the mean; that is an editorial assumption for orientation, not a trial statistic. Nothing here is medical advice or a dosing recommendation.

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Retatrutide results week by week (12 mg regimen)

The table gives the expected cumulative weight loss at each week for a participant following the 12 mg escalation schedule, with the dose in effect that week. Measured trial time points are marked; the rest are interpolations along the published curve.

Week	Dose that week	Cumulative weight loss (group mean)	Source
Week 1	2 mg	0.5-1%	interpolated
Week 2	2 mg	1-1.5%	interpolated
Week 3	2 mg	1.5-2.5%	interpolated
Week 4	2 mg	2-3%	Phase 2, measured
Week 5	4 mg	2.5-3.5%	interpolated
Week 6	4 mg	3-4%	interpolated
Week 7	4 mg	3.5-4.5%	interpolated
Week 8	4 mg	4-5%	Phase 2, measured
Week 9	6 mg	5-6%	interpolated
Week 10	6 mg	6-7.5%	interpolated
Week 11	6 mg	7-8.5%	interpolated
Week 12	6 mg	8-10%	Phase 2, measured
Week 14	9 mg	10-11.5%	interpolated
Week 16	9 mg	12-13%	Phase 2, measured
Week 20	12 mg	15-16%	interpolated
Week 24	12 mg	~17.5%	Phase 2, measured
Week 36	12 mg	21-22%	Phase 2, measured
Week 40	12 mg	15.3% in type 2 diabetes	TRANSCEND-T2D-1, measured
Week 48	12 mg	24.2%	Phase 2, measured (end of trial)
Week 68	12 mg	28.7%	TRIUMPH-4, measured
Week 80	12 mg	28.3% (20.8% with type 2 diabetes; 22.6% with cardiovascular disease)	TRIUMPH-1, -2, -3, measured
Week 104	12 mg	30.3% (BMI 35+ subgroup)	TRIUMPH-1 extension

For a person starting at 250 lb (113 kg), those means translate to roughly 3-4 lb by week 2, 5-7 lb by week 4, 10-12 lb by week 8, 20-25 lb by week 12, 44 lb by week 24, 60 lb by week 48 and about 71 lb by week 80.

Two cautions. First, the table is the 12 mg arm; the 4 mg and 9 mg arms lose less (19.0% and 25.9% at 80 weeks in TRIUMPH-1). Second, products sold online as “reta” are unverified research chemicals of unknown content, and there is no reason to expect their results to track this table; the first real-world analysis of grey-market users (a 2026 preprint) found about half the weight loss of trial participants at 12 months. See Why You Can’t Safely Buy Retatrutide Online.

Dose Escalation Schedule

The weight loss timeline is shaped by the escalation protocol. Retatrutide is not started at the maintenance dose; patients step up over about four months to limit gastrointestinal side effects:

Week	Dose
Weeks 1-4	2 mg
Weeks 5-8	4 mg
Weeks 9-12	6 mg
Weeks 13-16	9 mg
Week 17 onward	12 mg (maintenance)

For the 9 mg maintenance dose, escalation ends at week 13. For the 4 mg maintenance dose, escalation ends at week 5.

Patients on the 12 mg regimen do not reach their full dose until approximately week 17. The early weeks therefore reflect sub-therapeutic exposure, and the weight loss observed during this period understates what happens once the full dose is reached.

Phase 2 Weight Loss Trajectory (48 Weeks)

The Phase 2 obesity trial published by Jastreboff et al. in the New England Journal of Medicine (2023) provides the most detailed time-course data available. The trial enrolled 338 adults with obesity or overweight and tracked weight at multiple time points over 48 weeks.

Key Milestones at the 12 mg Dose

Time Point	Mean Weight Loss	Phase of Treatment
Week 4	~2-3%	Dose escalation (2 mg)
Week 8	~4-5%	Dose escalation (4 mg)
Week 12	~8-10%	Dose escalation (6 mg)
Week 16	~12-13%	Dose escalation (9 mg)
Week 24	~17.5%	Early maintenance (12 mg)
Week 36	~21-22%	Continued maintenance
Week 48	-24.2%	End of treatment period

Key Observations from Phase 2

Slow start during escalation (weeks 0-12). Weight loss during the first 12 weeks was modest, approximately 8-10% at the 12 mg dose. This reflects the low starting doses and the time required to reach therapeutic drug levels. The pace of early weight loss is not a guide to the eventual response.

Acceleration after reaching maintenance dose (weeks 12-24). The rate of loss increased once participants reached their maintenance doses. Between weeks 12 and 24 the 12 mg group lost approximately 7-8 additional percentage points, reflecting full triple-receptor engagement at therapeutic levels.

Continued loss without plateau (weeks 24-48). Weight loss continued through the full 48-week treatment period. The rate slowed in the later weeks as a new energy balance was approached, but the curve had not levelled off by week 48. The 24.2% at 48 weeks was not the maximum achievable with continued treatment.

Dose-Response at 24 Weeks

Dose	Mean Weight Loss at 24 Weeks
Placebo	~1.5%
1 mg	~5%
4 mg (escalating)	~11%
8 mg (escalating)	~16%
12 mg (escalating)	~17.5%

Phase 3 Results: Extended Timeline Data

TRIUMPH-4 (68 Weeks)

TRIUMPH-4 extended treatment to 68 weeks in 445 adults with obesity and knee osteoarthritis:

Time Point	9 mg	12 mg	Placebo
Week 68	-26.4%	-28.7%	-2.1%

The 28.7% at 68 weeks exceeds the 24.2% at 48 weeks from Phase 2 by about 4.5 percentage points over 20 additional weeks of treatment, confirming that the curve was still descending beyond 48 weeks.

Source: Eli Lilly press release, December 2025 (topline; not yet peer-reviewed).

TRIUMPH-1 (80 Weeks)

The pivotal TRIUMPH-1 obesity trial (2,339 adults, no diabetes), presented at ADA 2026, extended the window to 80 weeks and produced the largest pivotal weight-loss readout to date:

Time Point	4 mg	9 mg	12 mg	Placebo
Week 80 (efficacy estimand)	-19.0%	-25.9%	-28.3%	-2.2%

Among the 12 mg group, 45.3% lost at least 30% of their body weight and 65.3% ended the trial with a BMI below 30. In a 104-week extension (BMI 35+ subgroup), mean weight loss reached -30.3% at 12 mg, so the curve was still descending well past 80 weeks.

Source: Eli Lilly press release (May 21, 2026); presented at ADA 2026 (June 6, 2026).

TRIUMPH-2 and TRIUMPH-3 (80 Weeks)

Reported on July 23, 2026, these two trials show how the 80-week endpoint shifts in harder-to-treat populations:

Trial and population	9 mg	12 mg	Placebo
TRIUMPH-2: obesity with type 2 diabetes (n=1,152)	-19.1%	-20.8%	-4.0%
TRIUMPH-3: BMI 35+ with cardiovascular disease (n=1,949)	-21.6%	-22.6%	-3.2%

TRIUMPH-2 also reported the 4 mg arm at -12.7%. Detail on both trials: TRIUMPH-2 and TRIUMPH-3 results.

TRANSCEND-T2D-1 (40 Weeks)

TRANSCEND-T2D-1 evaluated retatrutide in 537 adults with type 2 diabetes over 40 weeks. Figures are from the peer-reviewed publication in The Lancet (June 6, 2026):

Time Point	4 mg	9 mg	12 mg	Placebo
Week 40	-11.5%	-13.9%	-15.3%	-2.6%

Weight loss was lower than in the obesity population, consistent with the established pattern that people with type 2 diabetes lose less on the same agents. Weight loss had not plateaued at 40 weeks.

Source: Rosenstock et al., The Lancet, June 6, 2026.

What to Expect at Each Stage

Estimates based on group means; individual variation is substantial.

Weeks 1-4 (2 mg dose)

• Weight loss is modest: 2-3% of body weight by week 4
• Appetite reduction may begin within the first week of injection
• Gastrointestinal side effects (nausea, decreased appetite) are most common during initial dosing; tingling or skin sensitivity (dysesthesia) can also start in the first weeks
• For a person weighing 250 lb (113 kg), this is approximately 5-7 lb (2-3 kg)
• Results are usually not visible to others at this stage

Weeks 5-8 (4 mg dose)

• Weight loss accelerates as the dose increases
• Cumulative loss of approximately 4-5% of body weight
• Appetite suppression becomes more pronounced
• Clothing may begin to fit differently
• For a 250 lb individual: approximately 10-12 lb (4-5 kg) lost

Weeks 9-16 (6 mg to 9 mg)

• The period of most rapid dose escalation
• Cumulative loss of approximately 8-10% by week 12 and 12-13% by week 16
• Results typically become noticeable to others
• Physical function improvements may become apparent (easier mobility, less joint discomfort)
• For a 250 lb individual: approximately 25-32 lb (11-15 kg) lost by week 16

Weeks 17-24 (reaching 12 mg maintenance)

• Full maintenance dose is reached around week 17 on the 12 mg regimen
• Weight loss rate is near its peak
• Cumulative loss of approximately 17-18% at 12 mg by week 24
• Significant changes in appearance, clothing size and physical capacity
• For a 250 lb individual: approximately 42-45 lb (19-20 kg) lost

Weeks 24-48

• Weight loss continues at a gradually declining rate
• By week 48, mean loss of 24.2% at 12 mg (Phase 2 data)
• Cardiometabolic improvements (blood pressure, lipids, blood glucose) are well established; see cardiovascular effects
• For a 250 lb individual: approximately 60 lb (27 kg) lost

Beyond 48 Weeks

• TRIUMPH-4 showed continued loss to 68 weeks (-28.7% at 12 mg) and TRIUMPH-1 to 80 weeks (-28.3%)
• The 104-week TRIUMPH-1 extension reached -30.3% in the BMI 35+ subgroup, so a plateau had still not clearly been reached at two years
• For a 250 lb individual: approximately 71 lb (32 kg) lost at 80 weeks

Comparison of Weight Loss Trajectories

Cross-trial comparison of retatrutide, tirzepatide and semaglutide at their highest studied doses, subject to all the usual limitations (different populations, durations and baselines):

Time Point	Retatrutide 12 mg	Tirzepatide 15 mg	Semaglutide 2.4 mg
~24 weeks	~17.5%	~13-15%	~10-12%
~48 weeks	-24.2%	~19-20%	~14-15%
~68-80 weeks	-28.7% (68 wk) / -28.3% (80 wk)	~20-22% (72 wk)	~15-17% (68 wk)

Retatrutide’s trajectory is steeper than both comparators at every time point, and the gap widens with duration. This is consistent with the glucagon component adding an energy-expenditure effect that compounds over time. Head-to-head trials are needed to confirm it; TRANSCEND-T2D-2 (retatrutide versus semaglutide in type 2 diabetes) is the first.

Why Weight Loss Continues Beyond 48 Weeks

1. Late dose optimization. The full maintenance dose is not reached until approximately week 17 on the 12 mg regimen, and steady-state exposure takes several more weeks, so the full pharmacological effect takes roughly 20-24 weeks to develop.

2. Body weight set point adjustment. As body weight falls, energy balance recalibrates. With triple receptor agonism maintaining appetite suppression and raised energy expenditure, a new equilibrium takes longer to reach than with less potent agents.

3. Glucagon-driven thermogenesis. The glucagon receptor component increases resting energy expenditure, extending the period of negative energy balance compared with GLP-1-only therapies.

4. Continued metabolic improvement. Progressive gains in insulin sensitivity may facilitate ongoing fat mobilisation even as total body weight decreases.

Reta Before and After: What the Data Can and Cannot Show

What “before and after” means here

“Before and after” on this page means clinical measurements from controlled trials: body weight, BMI, body composition (DXA where available) and metabolic markers. Retatrutide is investigational and not commercially available, so there are no verified patient before-and-after photographs.

Images circulating online as retatrutide transformations should be treated with scepticism. They may show results from other GLP-1 drugs, may be fabricated, or may show people who used unapproved research compounds of unknown content.

BMI Changes

What the Phase 2 mean result represents in BMI terms for a hypothetical 5’8” individual:

Starting BMI	Starting Weight	After 24.2% Loss	New BMI
35 kg/m2	230 lb (104 kg)	174 lb (79 kg)	26.5 kg/m2
40 kg/m2	263 lb (119 kg)	199 lb (90 kg)	30.3 kg/m2
45 kg/m2	296 lb (134 kg)	224 lb (102 kg)	34.1 kg/m2

At the Phase 3 level of weight loss (-28.3% to -28.7%), many people starting in the Class III range (BMI 40+) would move into the overweight or Class I range, which is exactly what TRIUMPH-1 measured: 65.3% of the 12 mg group ended below a BMI of 30.

Frequently Asked Questions

What should I expect at week 2 on reta?

Very little on the scale. At week 2 the dose is still 2 mg, and the group mean in trials is roughly 1-1.5% of body weight (3-4 lb for a 250 lb person). Appetite reduction and some nausea are the typical week-2 experience (what the trials recorded for nausea); the weight change comes later.

What about week 4, week 6 and week 8?

Trial means at 12 mg: about 2-3% by week 4 (end of the 2 mg step), 3-4% around week 6, and 4-5% by week 8 (end of the 4 mg step). For a 250 lb person that is 5-7 lb, 8-10 lb and 10-12 lb respectively.

What are typical 10 week and 12 week results?

About 6-7.5% by week 10 and 8-10% by week 12, still during escalation at 6 mg. Week 12 is usually the point at which the change becomes visible to other people. It is also when protein intake starts to matter for keeping muscle: see diet and nutrition on retatrutide and what the data show on muscle preservation.

How long does retatrutide take to work?

Appetite falls within the first week for most people, and measurable weight loss begins within 2-4 weeks. Because the drug is escalated over about 17 weeks to the 12 mg maintenance dose, clinically significant loss (visible change and metabolic improvement) generally takes 8-16 weeks, and the fastest phase of loss comes after week 17.

When will I see visible results?

Trial participants at 12 mg had lost about 8-10% by week 12. A 5-10% loss usually produces noticeable changes in clothing fit, facial appearance and comfort, so visible results are typically expected within 8-12 weeks, with the most dramatic changes after the maintenance dose is reached.

Does weight loss stop at some point, or does it keep going?

It keeps going for at least two years in the trials. Phase 2 had not plateaued at 48 weeks (24.2%), TRIUMPH-4 reached 28.7% at 68 weeks, TRIUMPH-1 reached 28.3% at 80 weeks, and the 104-week extension reached 30.3% in the BMI 35+ subgroup. The rate slows, but a plateau had not clearly arrived at 104 weeks. What happens after stopping is a different question: weight regain after retatrutide.

How does the timeline differ for people with type 2 diabetes?

Slower and smaller. TRANSCEND-T2D-1 showed -15.3% at 12 mg over 40 weeks, and TRIUMPH-2 showed -20.8% at 80 weeks in people with obesity and type 2 diabetes, against -28.3% in TRIUMPH-1 without diabetes. The attenuation is well documented across the incretin class. Weight loss had not plateaued at 40 or 80 weeks in either trial.

What happens to weight loss if the dose is reduced?

The trials did not systematically study dose reduction after reaching maintenance. Based on class data and retatrutide’s own dose-response (-19.0% at 4 mg versus -28.3% at 12 mg at 80 weeks in TRIUMPH-1), a lower dose would be expected to give less appetite suppression and slower loss or some regain.

Are the trial timelines realistic for real-world use?

Trials reflect controlled conditions: regular monitoring, dietary counselling and screened, motivated participants with a pharmaceutical-grade product. The one real-world dataset so far, a 2026 preprint on grey-market users, found roughly half the trial weight loss at 12 months with the same heart-rate rise. Approved-drug real-world results for retatrutide do not exist yet because the drug is not approved. The legitimate routes to the trial-grade product are a clinical trial or, for severe refractory obesity, expanded access.

Summary

The weight loss timeline with retatrutide follows a predictable pattern shaped by the escalation schedule and the time needed for full pharmacological effect. During the first 12 weeks of escalation, loss is modest (about 8-10% at the 12 mg regimen). After the maintenance dose is reached around week 17 the rate accelerates, and loss continues for at least two years: 24.2% at 48 weeks (Phase 2), 28.7% at 68 weeks (TRIUMPH-4), 28.3% at 80 weeks (TRIUMPH-1) and 30.3% at 104 weeks in the heaviest subgroup. People with type 2 diabetes or cardiovascular disease lose less (20.8% and 22.6% at 80 weeks). The trajectory is steeper and longer than those reported for tirzepatide and semaglutide in cross-trial comparisons. Individual responses vary, but the data give a reasonable framework for expectations at each week.