PepGuide
Fat lossResearch / off-labelSubQ

Retatrutide

Triple agonist (GLP-1 / GIP / glucagon), once weekly; the strongest weight-loss compound tested in humans (~28% in late trials). Not yet FDA-approved. A find-your-sweet-spot drug: ramp slowly and stop climbing once appetite is well controlled. Most land at 4–8 mg/week, no need to reach the top. Symptom-gated: step up only when the current dose feels comfortable, never on a fixed calendar.

Typical dose
4 mg
Timing
Once weekly (splittable into two shots/…
Where
SubQ, abdomen, outer thigh, or upper arm

Titration, once weekly, self-paced (symptom-gated)

Step 1
2.5u
0.5 mg · Once weekly
Hold ~1 week before stepping up.
Step 2
5u
1 mg · Once weekly
Hold ~1 week before stepping up.
Step 3
10u
2 mg · Once weekly
Hold 2–4 weeks before stepping up.
Step 4
15u
3 mg · Once weekly
Hold 2–4 weeks before stepping up.
Step 5
20u
4 mg · Once weekly
Sweet-spot range begins. Hold as needed, 2–4 weeks+.
Step 6
25u
5 mg · Once weekly
Hold as needed, 2–4 weeks+.
Step 7
30u
6 mg · Once weekly
Hold as needed, 2–4 weeks+.
Step 8
35u
7 mg · Once weekly
Hold as needed, 2–4 weeks+.
Step 9
40u
8 mg · Once weekly
Hold as needed, 2–4 weeks+.
Step 10
45u
9 mg · Once weekly
Hold as needed, 2–4 weeks+.
Step 11
50u
10 mg · Once weekly
Hold as needed, 2–4 weeks+.
Step 12
55u
11 mg · Once weekly
Hold as needed, 2–4 weeks+.
Step 13
60u
12 mg · Once weekly
Ceiling. Max dose, do not exceed.

Units @ 20 mg/mL. Pace it yourself, nothing here is on a clock. Move through 0.5 → 1 → 2 mg (~1 week each), then step +1–2 mg as you feel ready, only when nausea-free. Hold each dose as long as it’s still working, you never have to go up. Most find their sweet spot at 4–8 mg; 12 mg is the ceiling; above ~6 mg is prescriber territory. Sex note: women tend to lose more and tolerate less, start at the low end. Split it to ease nausea: any weekly dose can go as two smaller shots/week (e.g. Mon & Thu), same weekly total, lower peak. Halve the mg and units (4 mg / 20u once → 2 mg / 10u twice). 1 unit = 0.2 mg, so mg × 5 = units.

Current FDA trial schedule (TRIUMPH, once weekly, fixed calendar)

Retatrutide, Current FDA trial schedule (TRIUMPH, once weekly, fixed calendar): dose by week9 mg6 mg4 mg2 mgWeeks 1–4: 2 mg2 mgWk 1–4Weeks 5–8: 4 mg4 mgWk 5–8Weeks 9–12: 6 mg6 mgWk 9–12Weeks 13–16: 9 mg9 mgWk 13–16
Weeks 1–4
2 mg · Once weekly
Fixed starting dose for everyone.
Weeks 5–8
4 mg · Once weekly
The 4 mg target group stops climbing here.
Weeks 9–12
6 mg · Once weekly
Weeks 13–16
9 mg · Once weekly
The 9 mg target group stops here.
Weeks 17+
12 mg · Once weekly
The 12 mg group, the trial ceiling.

How to read it: everyone starts at 2 mg once weekly and steps up on a fixed 4-week calendar (2 → 4 → 6 → 9 → 12 mg). Each person was assigned a target of 4, 9, or 12 mg and simply stopped climbing once they reached it. No dose-splitting; pace is set by the calendar, not by symptoms.

Cycle & timing

Timing: Once weekly (splittable into two shots/week, e.g. Mon & Thu, same weekly total).

Where: SubQ, abdomen, outer thigh, or upper arm. Rotate.

Men & women

Sex note: women tend to lose more and tolerate less, start at the low end.

Men: In men, excess fat lowers testosterone; GLP-1 raises total testosterone, SHBG and gonadotropins as weight drops, and improves sperm and erectile function; and preserves fertility, unlike TRT (which suppresses sperm).
Women: Women lose more than men at the same dose but report more GI (start lower). In PCOS they improve cycles, lower free testosterone and raise ovulation; a real unplanned-pregnancy risk. Stop before conceiving.