1# Retatrutide: Spark Notes Guide
2
3## What It Is (One Sentence)
4
5A once-weekly injectable from Eli Lilly that activates three hormone receptors (GLP-1 + GIP + Glucagon) to produce ~25-29% weight loss—the most powerful obesity drug in development.
6
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8
9## The Triple Mechanism
10
11| Receptor | What It Does | Drugs That Use It |
12|----------|--------------|-------------------|
13| **GLP-1** | Kills appetite, slows digestion, improves blood sugar | Ozempic, Wegovy |
14| **GIP** | Amplifies GLP-1 effects, improves nutrient handling | Added in Mounjaro/Zepbound |
15| **Glucagon** | Increases metabolism, burns liver fat | **Only in Retatrutide** |
16
17The glucagon component is the differentiator—it makes you burn more calories (not just eat less) and has dramatic effects on liver fat.
18
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20
21## Key Numbers
22
23| Metric | Result |
24|--------|--------|
25| Weight loss (Phase 3, 68 weeks) | 28.7% (~71 lbs from 249 lb baseline) |
26| Liver fat reduction | 82-86% |
27| Fatty liver resolution | 93% achieved normal liver fat |
28| Prediabetes → Normal | 72% reverted to normoglycemia |
29| HbA1c reduction (diabetics) | Up to 2.0% |
30| LDL cholesterol reduction | ~20% |
31| Blood pressure reduction | ~14 mmHg systolic |
32
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34
35## Side Effects
36
37**Common (GI):** Nausea (38-43%), diarrhea (33%), vomiting (21%), constipation (22-25%)
38- Mostly during dose escalation
39- Improve over time
40
41**New Signal:** Dysesthesia (tingling/altered skin sensation)
42- 9% at 9mg, 21% at 12mg
43- Usually mild, rarely causes discontinuation
44
45**Discontinuation rates:** 12-18% (higher than existing GLP-1s)
46
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48
49## Alcohol/Addiction Effects
50
51GLP-1 drugs (including retatrutide) reduce cravings by blunting dopamine release in the brain's reward centers (VTA, nucleus accumbens). Studies show ~68% reduction in alcohol intake among heavy drinkers. Many users report simply "forgetting" to drink or losing interest entirely.
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54
55## Status
56
57- **Now:** Phase 3 trials (TRIUMPH program)
58- **First Phase 3 results:** December 2025 ✓ (TRIUMPH-4 successful)
59- **Remaining trials:** 7 more readouts expected 2026
60- **Expected approval:** 2026-2027
61
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63
64## Conservative Dosing Protocol
65
66Clinical trials use aggressive 4-week escalation starting at 2mg. This approach is more conservative to minimize side effects:
67
68| Week | Dose | Notes |
69|------|------|-------|
70| 1-2 | 0.5 mg | Sub-therapeutic introduction |
71| 3-4 | 1.0 mg | Build tolerance |
72| 5-6 | 1.0 mg | Hold to confirm tolerance |
73| 7-8 | 1.5 mg | First meaningful therapeutic dose |
74| 9-10 | 1.5 mg | Hold and assess response |
75| 11-12 | 2.0 mg | Low therapeutic range (optional) |
76| 13+ | Hold | Reassess every 4-6 weeks |
77
78**Key principles:**
79
80- **Slower = fewer GI sides.** Trial data showed extended escalation significantly reduced nausea/vomiting
81- **You may not need high doses.** 12mg is for maximizing weight loss in severely obese populations; 2-4mg may be sufficient
82- **Hold at any dose if sides are problematic** before advancing
83- **Protein stays high** (1g per lb target bodyweight)—these drugs can accelerate lean mass loss if protein is inadequate
84- **Training intensity stays up**—the stimulus to retain muscle is non-negotiable
85
86**When to consider advancing:**
87
88- Weight loss stalls for 3+ weeks
89- Appetite suppression diminishes noticeably
90- No meaningful side effects at current doseRetatrutide: Spark Notes Guide