I lost 90lbs on retatrutide over 11 months. Here's every dose I took, how my results compared to Phase 2 clinical trial data, and the protocol I'd follow if I were starting today.
Disclaimer: Retatrutide is not yet FDA-approved. This post describes my personal experience and summarizes publicly available Phase 2/3 clinical trial data (Jastreboff et al., NEJM 2023; TRIUMPH-4, Dec 2025). This is not medical advice. Always work with a qualified healthcare provider before starting any medication.
It targets three receptors simultaneously - that changes everything about how you ramp up
The glucagon receptor activation is why you can't ramp up retatrutide the same way you might with Ozempic. When all three receptors fire simultaneously, your GI tract, sleep, blood pressure, and a few things you didn't expect are all adapting at once. I paid for going too fast in Month 3 - skin sensitivity, near-fainting, insomnia every single day at 4am. I didn't need to push as hard as I did.
Jastreboff et al., NEJM 2023 - 338 participants, 48 weeks · PubMed
The trial wasn't just testing different doses - it was also testing how fast you start. The same 8mg target dose was assigned to two groups: one starting at 2mg (slow), one starting at 4mg (fast). Here's the key insight: both groups lost the exact same amount of weight - but the slower start group had significantly fewer GI side effects. The trial reported weight loss for these subgroups combined, which is why the percentages match. The starting dose doesn't change your results. It changes how much you suffer getting there.
| Trial Arm | Starting Dose | Target | Wt Loss @ 24 wks | Wt Loss @ 48 wks | Starting Dose Impact |
|---|---|---|---|---|---|
| 1 mg | 1 mg | 1 mg | −7.2% | −8.7% | - |
| 4 mg (slow start) | 2 mg | 4 mg | −12.9% | −17.1% | Fewer GI events |
| 4 mg (fast start) | 4 mg | 4 mg | −12.9% | −17.1% | More GI events |
| 8 mg (slow start) | 2 mg | 8 mg | −17.3% | −22.8% | Fewer GI events |
| 8 mg (fast start) | 4 mg | 8 mg | −17.3% | −22.8% | ~2× more GI events |
| 12 mg | 2 mg | 12 mg | −17.5% | −24.2% | Slow start only arm |
| Placebo | - | - | −1.6% | −2.1% | - |
† Weight loss results reported as combined groups per Jastreboff et al., NEJM 2023. The slow vs. fast start comparison was designed to measure tolerability, not efficacy.
Avg Weight Loss @ 48 Weeks by Dose Group - Phase 2, NEJM 2023
8mg → 12mg adds only ~1.4 percentage points more average weight loss. That marginal gain costs considerably more in side effects for many people.
Announced December 11, 2025 - 68 weeks, 445 participants · Lilly press release
TRIUMPH-4 only tested the two highest doses (9mg and 12mg) and ran 20 weeks longer than Phase 2 - which explains why the numbers went up. Weight loss kept accumulating past the 48-week Phase 2 cutoff. The titration protocol was identical: start at 2mg, increase every four weeks. One new safety signal appeared that wasn't in Phase 2 at all.
Avg Weight Loss by Dose - Phase 2 (48 wks) vs Phase 3 TRIUMPH-4 (68 wks)
Phase 3 used the same titration as Phase 2. The extra weight loss at 12mg (24.2% to 28.7%) reflects 20 additional weeks of treatment, not a different protocol.
Phase 2 vs Phase 3 - Head to Head
| Metric | Phase 2 (48 wks) | Phase 3 TRIUMPH-4 (68 wks) | Takeaway |
|---|---|---|---|
| Participants | 338 | 445 | Larger, more robust dataset |
| Duration | 48 weeks | 68 weeks | 20 extra weeks of weight loss |
| Doses tested | 1, 4, 8, 12 mg | 9 mg and 12 mg only | Phase 3 focused on highest doses |
| Titration start | 2 mg once weekly | 2 mg once weekly | Identical - start low confirmed |
| Weight loss at 9 mg | Not tested | −26.4% (−29.1 kg) | New data point between 8 and 12mg |
| Weight loss at 12 mg | −24.2% | −28.7% (−71.2 lbs) | +4.5pp from 20 extra weeks |
| Placebo weight loss | −2.1% | −2.1% | Consistent across both trials |
| Dysesthesia / skin sensitivity | Not reported | 8.8% (9mg) / 20.9% (12mg) | New signal - see note below |
| Discontinuation due to AEs | Not prominently reported | 12.2% (9mg) / 18.2% (12mg) | Some stopped due to excessive weight loss |
Dysesthesia is the clinical term for abnormal skin sensations - tingling, numbness, altered sense of touch. It didn’t show up formally in Phase 2, but appeared in 20.9% of participants at 12mg in Phase 3. I experienced this from Month 3 onward and had no idea what it was. The feeling was like a constant low-grade sunburn across my skin. Claritin helped significantly. The fact that it’s now in the Phase 3 safety data with a name and a rate validates what a lot of people have been reporting anecdotally. If you feel this, it’s real, it’s documented, and dropping your dose does make it go away quickly.
Phase 3 TRIUMPH-4 - GI Side Effect Rates at High Doses
| Side Effect | 9 mg | 12 mg | Placebo | My Experience |
|---|---|---|---|---|
| Nausea | 38.1% | 43.2% | 10.7% | Minimal - split dosing likely helped |
| Diarrhea | 34.7% | 33.1% | 13.4% | Occasional but not severe |
| Constipation | 21.8% | 25.0% | 8.7% | Mild, manageable |
| Vomiting | 20.4% | 20.9% | 0.0% | Never experienced this |
| Decreased appetite | 19.0% | 18.2% | 9.4% | Strong - this is the whole point |
| Dysesthesia (skin sensitivity) | 8.8% | 20.9% | 0.7% | Significant from Month 3 - Claritin helped |
Source: Lilly TRIUMPH-4 press release, December 11, 2025. GI events were consistent with other incretin therapies and generally mild-to-moderate. Most did not lead to discontinuation.
TRIUMPH-1 and TRIUMPH-2 (results expected in 2026) include a formal 4mg maintenance dose arm - meaning Lilly is actually studying what I stumbled onto accidentally in Month 8. Real maintenance dosing data is coming. This is the biggest missing piece from the current clinical picture, and it’s being addressed. Keep an eye on those readouts if you’re planning a long-term protocol.
Four approaches - toggle between them to compare
| Phase | Dose | Notes |
|---|---|---|
| Weeks 1–4 | 2 mg once weekly | GI adaptation period. Don't rush this. |
| Weeks 5–8 | 4 mg once weekly | First therapeutic range. Appetite suppression strengthens. |
| Weeks 9–12 | 8 mg once weekly | Strong weight loss begins here. |
| Week 13+ | 12 mg once weekly (max) | Maximum efficacy per trial data. Not everyone needs this. |
TRIUMPH-4 (Dec 2025, 445 participants) used the same titration steps as Phase 2 - start at 2mg, increase every 4 weeks. The only difference: target doses were 9mg and 12mg only. No 4mg or 8mg maintenance arms were tested. Both doses produced record-breaking weight loss at 68 weeks.
| Phase | Dose | Target: 9mg arm | Target: 12mg arm |
|---|---|---|---|
| Weeks 1–4 | 2 mg once weekly | Same | Same |
| Weeks 5–8 | 4 mg once weekly | Same | Same |
| Weeks 9–12 | 8 mg once weekly | Same | Same |
| Week 13+ | 9 mg (target) | −26.4% at 68 wks | ↑ continues to 12mg |
| Week 17+ | 12 mg (target) | Stayed at 9mg | −28.7% at 68 wks |
New at Phase 3: Dysesthesia (skin sensitivity) appeared in 20.9% of participants at 12mg - a signal not captured in Phase 2. If you feel this, it’s now in the clinical literature. Dropping dose resolves it quickly. See the Phase 3 section above for full side effect rates.
| Phase | Dose | Notes |
|---|---|---|
| Weeks 1–4 | 1 mg once weekly | Ultra-gentle start; used as its own trial arm in Phase 2. |
| Weeks 5–8 | 2 mg once weekly | Slow GI adaptation. |
| Weeks 9–12 | 4 mg once weekly | Mid-range; still good efficacy (~17% loss at 48 wks). |
| Weeks 13–16 | 8 mg once weekly | Strong weight loss zone. |
| Week 17+ | 12 mg if tolerated | Not everyone needs to push to maximum. |
| Month | Avg Weekly Dose | What Was Happening |
|---|---|---|
| Month 1 | ~2.7 mg/wk split | 1–2.5mg every 3–4 days. Zero side effects. Food noise gone by day 2. |
| Month 2 | ~5.8 mg/wk split | Slowly titrating. First side effects: lightheadedness, fatigue, reduced libido. |
| Month 3 | ~8.1 mg/wk split | Best loss month (-25.5 lbs). Also worst side effects. Insomnia + skin sensitivity hit. |
| Month 4 | 8.6 → dropped to 2.5 mg/wk | Couldn't sustain the high dose. Dropped, side effects cleared within days. |
| Months 5–6 | ~1.2–2.5 mg/wk | Vacation / maintenance mode. Still losing weight slowly. |
| Month 8 | ~1.8 mg/wk | Found maintenance sweet spot. Held flat at 200 lbs with heavy cycling. |
Click any point on the blue line to see what was happening that month
Click any blue dot to see month notes
My experience cross-referenced with what the Phase 2 trial reported
Clinical trial data only tells part of the story. We analyzed 14,252 real-world posts from Reddit communities to see what side effects people actually report - including frequency, severity, and how they managed them.
| Weekly Dose | Severity | My Experience | Trial Data |
|---|---|---|---|
| ~1–3 mg/wk | Mild | Fatigue, food noise gone completely | Generally well tolerated; mild nausea in some |
| ~4–6 mg/wk | Moderate | Lightheadedness when standing, fatigue, reduced sex drive starting here | GI events increasing; mostly mild-moderate |
| ~4–9 mg/wk | Moderate | Reduced sex drive / libido - essentially gone by Month 3. Came back fully after stopping. | Not formally tracked in Phase 2 but widely reported anecdotally across retatrutide Reddit communities. Likely shared mechanism with other GLP-1s. |
| ~7–9 mg/wk | Significant | Insomnia (4am daily), allodynia/skin sensitivity, near-fainting, BP dropped to 105/69 | GI events common; dose-dependent heart rate increase peaked ~week 24 |
| ~1.5–2 mg/wk (maint.) | Mild | Early waking (4–5am) only. Everything else resolved. | No formal maintenance arm tested in Phase 2 |
Allodynia - a constant low-grade sunburn feeling across your skin - and the 4am wake-up that wouldn't quit for months. Neither of these appeared on any side effects list I read before starting. I only figured out the skin thing after obsessive Googling. Claritin fixed it almost immediately. I go deep on both in my retatrutide side effects post, including how common they are across 14,252 Reddit reports we analyzed.
Probably not. Here's what the data actually shows.
My weekly average peaked around 8–9mg via split dosing. I lost 90 lbs. The jump from 8mg to 12mg buys you roughly 1.4 percentage points more average weight loss at the cost of meaningfully more side effects for many people. Don't chase the number. Chase the result.
This is where most people - including me - go wrong
The clinical trials studied weight loss, not long-term maintenance - so there's no official protocol for this yet. What I stumbled onto in Month 8: ~1.5–2mg per week held me flat at 200 lbs while I was cycling heavily and eating more. That's a fraction of a therapeutic dose, but it was enough to keep food noise manageable and my appetite in check.
Spend 2+ months at maintenance dose (1–2mg) before attempting to stop completely. Let your body stabilize at the new weight before removing the support entirely.
Stopped cold turkey off my last vial in November. No plan. No taper. Gained 20+ lbs in 3 months before getting back on in Month 10.
Here’s something worth knowing: TRIUMPH-1 and TRIUMPH-2 both include a formal 4mg/week maintenance arm - meaning Eli Lilly is actually studying this question. Nobody on the trials to date has been randomized to a maintenance protocol; the current trials studied weight loss, not weight maintenance. That data is expected in 2026. Until then, everything about maintenance dosing - including my 1.5–2mg experience - is anecdotal. But the fact that Lilly is studying exactly this dose range suggests the direction is right.
When I restarted in Month 10 after about 6 weeks off, I went back to 2.5mg every 3–4 days - starting well below where I’d left off. Your GI tolerance resets faster than you’d think. Had I jumped straight back to the 8–9mg/week I was taking at peak, the side effects would have been brutal.
Here’s why this is more nuanced than a simple rule: retatrutide has a half-life of approximately 6 days. That means:
But there’s another variable beyond pharmacokinetics: how long you were on the drug, and at what dose. Someone who spent 3 months at 8mg has a very different GI adaptation than someone who spent 3 months at 2mg. There’s no clinical guidance on restart protocols right now - this is entirely self-experimentation territory. My honest advice: err on the side of starting lower than feels necessary. The cost of starting too low is a couple extra weeks before you feel the full effect. The cost of starting too high is a week of brutal side effects.
My practical approach: After a break of more than 3–4 weeks, I start back at 2.5mg every 3–4 days regardless of where I left off. After a shorter break of 1–2 weeks, I’d probably drop one step below my previous dose and see how I feel before increasing. None of this is in the literature - it’s pattern recognition from my own experience and what I’ve read from others doing the same thing. Your body re-adapts faster the second time around, so don’t panic if you have to back off.
Common dosing questions
The Phase 2 trial used 1 mg or 2 mg once weekly as starting doses. 2mg is now considered standard; 1mg is for people who want a more conservative ramp or have had GI issues on other GLP-1s. Either way, the principle is the same: start low and give your body time to adapt before increasing.
Once weekly in clinical trials. Some people in the real-world community use split dosing - injecting every 3–4 days instead of once weekly - to reduce peak-related nausea. I did this throughout my entire 11 months. It likely explains why I had almost zero nausea despite hitting relatively high weekly dose totals. The tradeoff is more frequent injections.
12 mg once weekly, based on Phase 2 and Phase 3 TRIUMPH trial data. This is the highest dose studied. Not everyone needs to reach 12mg - 8mg produced 22.8% average weight loss vs 24.2% at 12mg. That's a small difference in return for a meaningful increase in side effects for many people.
Food noise reduction typically starts within the first week. Noticeable weight changes usually appear by weeks 4–6. Real momentum builds as you titrate into the 4–8mg range. I lost 18.6 lbs in my first month, but I was also exercising consistently - that's likely faster than typical.
Approximately 6 days (144 hours), which supports once-weekly dosing and means it reaches steady state within 4–5 weeks at each dose level. The long half-life is also why split dosing can reduce peak-related side effects - you're smoothing out the plasma concentration curve between injections.
Hunger returns - often intensely and quickly. I cover my full experience with this in a dedicated post. The short version: don't stop cold turkey from a high dose. Taper down to maintenance over several months, stabilize at that weight for a couple of months, then consider stopping only with a concrete plan for diet and exercise in place.
Hair loss (telogen effluvium) can occur with rapid weight loss on any GLP-1 medication, including retatrutide - it's related to the caloric deficit and physiological stress rather than the drug itself. I didn't experience significant hair loss personally. Adequate protein intake and not cutting calories too aggressively are generally the best preventive strategies.
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