Retatrutide Results Timeline: What the Trials Measured

What did the retatrutide trial measure over time?

The phase 2 trial tracked mean percentage change in body weight across 48 weeks in adults with obesity, with the largest reductions in the highest dose group (Jastreboff et al., 2023).

This was a randomized, placebo-controlled trial that assigned participants to several dose groups, up to 12 mg. The main readout was percentage change in body weight, measured at set checkpoints through week 48. The page below reports those phase 2 results only; results from larger, later trials are not published here.

One point matters for a timeline: these numbers are group means. The trial reported the average change across everyone in a dose group. Individual participants sat above and below that average.

How much weight loss did retatrutide show at 24 weeks?

In the 12 mg group, mean body weight fell about 17.5% by week 24 (Jastreboff et al., 2023).

Week 24 is the halfway mark of the 48 week trial. Reaching about 17.5% by the midpoint tells you the early part of the curve is where most of the change accumulated. That early-and-fast pattern is common across incretin-class research and is one reason a results timeline looks like a steep slope that gradually bends.

How much at 48 weeks, the full trial window?

By week 48, the 12 mg group reached a mean of about 24.2% below baseline (Jastreboff et al., 2023).

This is the top-line figure most often quoted for retatrutide. All reductions in the active dose groups were larger than the placebo group over the same window.

The ranges below reflect what published studies and commonly studied research protocols report. This is educational, not a prescription or a personal recommendation. The "12 mg" label is the trial dose group, reported so the timeline numbers have context, not a dose for the reader.

A detail worth flagging: in the phase 2 trial, mean weight was still trending down at week 48 in the higher dose groups (Jastreboff et al., 2023). That means the 48 week figure may not represent a final plateau, and it should not be read as a ceiling or a target.

Why does the results curve slow down over time?

Weight loss on incretin-class therapy is fastest early and tends to flatten as the body adapts (Wilding et al., 2021, STEP 1; Rosenbaum and Leibel, 2010).

Two things drive the bend in the curve. First, in the STEP 1 semaglutide trial, weight fell from the first check at week 4, reached its lowest point (nadir) near week 60, and the rate of loss slowed well before that, so the curve flattens with time on treatment (Wilding et al., 2021). Second, as a person loses weight, resting energy expenditure falls more than body-size change alone would predict, a response called adaptive thermogenesis (Rosenbaum and Leibel, 2010). This physiology resists further loss and helps explain why early weeks show the biggest moves.

How does the retatrutide timeline compare to tirzepatide and semaglutide?

Retatrutide's 48 week mean is numerically the highest of the three, but each trial ran for a different length, so the timelines are not a fair head-to-head (Jastreboff et al., 2023; Jastreboff et al., 2022; Wilding et al., 2021).

Read the table with care. Retatrutide reached about 24.2% in 48 weeks, while the tirzepatide and semaglutide figures come from longer trials of 72 and 68 weeks. Different enrollment, dose schedules, and endpoints also separate these studies. The honest read is that retatrutide's phase 2 numbers look strong on their own timeline, not that one drug "beats" another in a direct comparison.

What happens to results after the trial or after stopping?

Trials of related incretin therapies report meaningful weight regain after treatment stops (Aronne et al., 2024; Wilding et al., 2022).

When tirzepatide was withdrawn in SURMOUNT-4, participants regained a substantial share of lost weight (Aronne et al., 2024). A similar pattern appeared after semaglutide stopped in the STEP 1 extension (Wilding et al., 2022). The adaptive thermogenesis physiology above is part of why (Rosenbaum and Leibel, 2010). Retatrutide-specific withdrawal data is limited in the published record here, so this pattern is inferred from related GLP-1-class trials rather than measured on retatrutide directly.

Should I expect this timeline for myself?

No. These are averages from a controlled research setting, not a forecast for any individual, and any decision about retatrutide belongs to a qualified clinician.

Group means hide wide individual variation. Trial participants were screened, monitored, and supported in ways that do not match self-guided use. This page is research education. It does not recommend retatrutide, a dose, or a schedule, and it makes no promise about what any reader will see in any number of weeks. In the trial, the highest dose group received 12 mg (Jastreboff et al., 2023); whether any compound or dose is appropriate for a given person is a clinical question, not a self-service one.