Who Is This Protocol For?
- Users comfortable with GLP-1 agonist side effects — prior experience helpful but not required
- People who want therapeutic levels quickly — appetite suppression typically begins within the first week
- Anyone following a provider-supervised regimen based on published Phase 3 trial design
Standard Dosage Chart (TRIUMPH-4)
| Week | Weekly Dose | Frequency | What to Expect |
|---|---|---|---|
| 1–4 | 2.0 mg | 1× weekly | Appetite suppression begins; nausea common weeks 1–3 |
| 5–8 | 4.0 mg | 1× weekly | Significant appetite control; GI events typically improve |
| 9–12 | 6.0 mg | 1× weekly | Most users' effective range; evaluate weight trajectory |
| 13–16 | 9.0 mg | 1× weekly | Only if 6 mg plateau; expect increased side effects |
| 17+ | 12.0 mg | 1× weekly | Maximum trial dose; ~20% dropout rate at this level |
Reta dosing chart: source is TRIUMPH-4 Phase 3 trial protocol. Each step is 4 weeks — the minimum for retatrutide to approach steady state (based on ~6-day half-life).
Phase 2 Efficacy Data by Dose
Jastreboff et al. (2023, N=338, 48 weeks) showed diminishing returns above 8 mg — the 12 mg arm added only 1.4 percentage points of weight loss with meaningfully higher GI adverse events. Many practitioners target 6–8 mg as the maintenance dose.
Why 2 mg Is the Starting Dose
The Phase 2 trial compared starting at 2 mg vs 4 mg when escalating to the same final dose. Starting at 2 mg produced lower nausea rates, comparable weight loss at 48 weeks, and better participant retention.
At steady state, 2 mg/week produces total drug exposure of approximately 3.7 mg equivalent — enough for measurable appetite suppression in most individuals while keeping GI burden manageable.
With a ~6-day half-life, ~54% of each dose is still active when the next injection is given. After 4 weeks on 2 mg/week, your total drug exposure is roughly 3.7 mg — not 2 mg. This accumulation is exactly why escalation must wait for steady state, and why doubling the dose feels like more than a doubling of effect.
How to Take This Protocol
Reta is injected subcutaneously once per week, on the same day each week. Pick a day that works for your schedule — consistency matters more than which day you choose. Common injection sites: abdomen (2 inches from navel), outer thigh, or upper arm. Rotate sites weekly. If you experience injection-day nausea, try evening dosing.
Companion Requirements
- Protein: 1 g per pound of lean body mass/day minimum. Critical for preventing ~30% lean mass loss seen in trials without adequate protein.
- Calorie floor: 1,500 cal/day regardless of appetite. Stronger appetite suppression starts earlier with this protocol.
- Resistance training: 3×/week minimum. Intensity over volume. If energy drops, reduce sets but maintain load.
- Carbohydrates: Moderate intake; avoid keto. Glucagon receptor activation is optimized with mixed-nutrient meals.
Exit Strategy
| Phase | Duration | Action |
|---|---|---|
| Pre-taper | 2 weeks | Increase calories by 200–300/day before last full dose |
| Taper 1 | 2 weeks | Reduce to 50% of working dose |
| Taper 2 | 2 weeks | Reduce to 25% of working dose |
| Post-taper | Ongoing | Maintain calorie + training habits; expect hunger rebound |
BMJ data suggests 4 kg/month regain without a structured exit protocol. Weight typically returns fully within 1.7 years of cessation without habit maintenance. The taper is non-negotiable.
Compare Starting Protocols
- Conservative Protocol — 0.5 mg start, slower titration for GI-sensitive users
- Split Dose Protocol — divide weekly dose across 2 injections