Semaglutide vs Tirzepatide vs Retatrutide
Semaglutide, tirzepatide, and retatrutide work through different receptor combinations which affect fat loss, muscle preservation, and metabolic breadth. This tool compares the compounds through clinical trial data — select a compound below.
Semaglutide
Ozempic, Wegovy
The gentle starter
Pure GLP-1 agonist — reduces appetite and slows digestion. Strongest cardiovascular outcome data (SELECT trial), extensive trial and safety data, and only incretin with an oral option.
GLP-1 only: satiety and insulin sensitivity
STEP-1 DXA substudy, non-diabetic obesity, 68 wk
Tirzepatide
Mounjaro, Zepbound
The fast track
GIP-dominant dual agonist — directly engages fat cells via GIP receptors. 47% more weight loss than semaglutide head-to-head. Body-comp advantage narrows in T2D where GIP is impaired.
GLP-1 + GIP: deeper metabolic rebalancing with improved nutrient partitioning
SURMOUNT-1 DXA, non-diabetic obesity, 72 wk — converges with sema in T2D
Retatrutide
Investigational (Phase 3)
The heavy hitter
Triple-agonist with redesigned receptor profile — stronger GIP (8.9×), plus glucagon for direct liver fat mobilization. Currently in Phase III trials. Requires meticulous muscle protection.
GLP-1 + GIP + Glucagon: whole-system metabolic rewiring with enhanced fat oxidation
*T2D DXA substudy, 36 wk (not directly comparable)
How It Works
Full-strength activation of the gut–brain satiety pathway — suppresses appetite, slows gastric emptying, and improves insulin signaling.
Smaller hunger signals, earlier fullness, flatter post-meal glucose spikes. Semaglutide's load-bearing advantages: the only GLP-1 with placebo-beaten cardiovascular outcomes (SELECT trial — 20% MACE reduction in n=17,604), histologic MASH resolution (ESSENCE Phase 3: 62.9% vs 34.1% placebo), and the only compound with direct head-to-head dose-comparison evidence (STEP-2: 1.0 mg retains ~73% of 2.4 mg effect). Lean-mass preservation requires adequate protein and resistance training regardless of which GLP-1 is used.
What % of People Hit Each Milestone?
Based on STEP-1 trial data (68 weeks, non-diabetic obesity)
Expected Weight Loss by Dose
| Dose | Weeks | Expected Loss | Notes |
|---|---|---|---|
| 0.25 mg | 0–4 | ~1% | Early titration |
| 0.5 mg | 4–8 | 2–3% | Appetite suppression begins |
| 1.0 mg | 8–12 | 4–6% | Noticeable trajectory |
| 1.7 mg | 12–16 | 7–9% | Most reach ≥5% |
| 2.4 mg | 16–68 | 12–15% | Full effect |
Complete Protocol Guide
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Maintain
Do not exceed this dosage. Always follow your healthcare provider's guidance.
Only increase if appetite returns or fat loss stalls. Slow and steady wins.
Advantages
- Most forgiving - easiest to start and adjust.
- Well-studied with good safety profile.
Watch Out For
- Single-receptor GLP-1 mechanism means all fat loss is indirect through caloric deficit — no direct fat-cell signaling like tirzepatide or retatrutide. Fat-to-lean ratio runs ~60:40 in non-diabetic populations (STEP-1 DXA), though it converges with tirzepatide in T2D (both ~86:14) where the GIP pathway is impaired.
- Fatigue and GI burden during titration are common; most discontinuations cluster in the escalation phase rather than at maintenance.
Semaglutide: Deep Dives
Clinical Monitoring Framework
Clinical Evidence
Medical Disclaimer
The content in this GLP-1 comparison guide is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider before beginning any new protocol, supplement, or medication.
How It Works
Lower dose than semaglutide because GIP carries most of the weight — still provides appetite suppression and gastric slowing
Burns fat directly — GIP receptors sit on fat cells themselves, triggering heat generation through a pathway GLP-1 cannot access
In non-diabetic populations, tirzepatide produces 47% more weight loss than semaglutide (SURMOUNT-5) and substantially better body composition (75:25 vs 60:40). In T2D, the ratio advantage disappears — head-to-head shows ~87:13 for both drugs. Still catabolizes muscle if you don't guard it.
What % of People Hit Each Milestone?
Based on SURMOUNT-1 trial data (72 weeks, non-diabetic obesity)
Expected Weight Loss by Dose
| Dose | Weeks | Expected Loss | Notes |
|---|---|---|---|
| 2.5 mg | 0–4 | ~2% | Starting dose |
| 5 mg | 4–8 | 4–6% | Entry therapeutic |
| 7.5 mg | 8–12 | 8–10% | Building |
| 10 mg | 12–16 | 12–15% | Strong effect |
| 15 mg | 16–72 | 18–21% | Maximum dose |
Complete Protocol Guide
Start
Build
Maintain
Do not exceed this dosage. Always follow your healthcare provider's guidance.
More powerful than sema - watch muscle loss if support isn't dialed in
Advantages
- Faster fat loss than semaglutide in head-to-head studies.
- Strong glucose control for diabetics.
Watch Out For
- Higher chance of GI side effects.
- Lean-mass preservation still requires adequate protein (≥1.6 g/kg) and resistance training — although SURPASS-3 sub-analysis (Sattar 2025) suggests some muscle-preservation advantage over semaglutide in non-diabetic populations, rapid weight loss without training support will compromise it.
Tirzepatide: Deep Dives
Clinical Monitoring Framework
Clinical Evidence
Medical Disclaimer
The content in this GLP-1 comparison guide is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider before beginning any new protocol, supplement, or medication.
How It Works
Engages at full intensity once therapeutic — appetite suppression and gastric slowing. Lower potency than native means it takes more drug to engage, not that the engaged signal is weaker
Highest-potency arm — saturates fastest as dose climbs. GIP engagement at the 1 mg microdose already exceeds tirzepatide at its 15 mg ceiling
Unique to retatrutide — direct hepatic fat oxidation and raised resting energy expenditure. Lower potency means later engagement on the dose curve, not a softer signal
Retatrutide hit ~17% weight loss in T2D at 36 weeks vs tirzepatide's ~13% at 40 weeks; the glucagon channel works regardless of diabetic status. Heart-rate rise is dose-dependent (+2–3 bpm at 1–4 mg, +5–6 bpm at 8 mg, +9.2 bpm at 12 mg / 24 wk in non-diabetic obesity) and attenuates roughly 40–50% from peak as weight loss progresses. Initial titration speed matters — faster step-ups produce higher HR peaks during the titration window and meaningfully more nausea. Microdose users have minimal cardiac and catabolic exposure. At higher bands, training and protein intake matter more.
*Body composition data comes from a Phase 2 DXA substudy in a T2D population (36 weeks, n=189; Lancet Diabetes & Endocrinology 2025). Semaglutide and tirzepatide ratios are from non-diabetic populations over longer durations (68–72 weeks). Metabolic differences between T2D and non-diabetic subjects affect how fat and lean mass respond to treatment — in particular GIP signaling is impaired in T2D — so these ratios are not directly comparable across compounds. Non-diabetic retatrutide body composition data does not yet exist (Phase 3 TRIUMPH DXA not yet reported).
What % of People Hit Each Milestone?
Based on Phase 2 (NEJM 2023) trial data (48 weeks, non-diabetic obesity (weight loss); t2d substudy (body comp, 36-wk dxa))
Expected Weight Loss by Dose
| Dose | Weeks | Expected Loss | Notes |
|---|---|---|---|
| 0.5–1 mg | 0–4 | ~3% | Activation phase |
| 2 mg | 4–8 | 5–7% | Early response |
| 4 mg | 8–12 | 10–12% | Similar to full sema |
| 8 mg | 12–24 | 18–20% | Large effect |
| 12 mg | 24–48 | 22–24% | Maximum; no plateau |
Complete Protocol Guide
Start
Build
Maintain
Do not exceed this dosage. Always follow your healthcare provider's guidance.
Glucagon-mediated effects (HR elevation, sustained lipolysis, peak hepatic-fat mobilization) are threshold-dependent endpoints that emerge as cumulative weekly exposure climbs — minimal at microdose (1–2 mg), detectable mid-range (4–6 mg), peak at 8–12 mg. Slow titration manages this.
Advantages
- Highest fat loss potential of any available option.
- Impacts metabolism and drives fat oxidation with glucagon.
Watch Out For
- Side effects highly sensitive to dose escalation.
- Dose-dependent resting heart rate rise: +2–3 bpm at 1–4 mg, +7 bpm peak at 12 mg by week 24, attenuates to dulaglutide-comparable by week 36 (Rosenstock 2023). The cardiac signal is real but not permanent — the rise fades over ~6 months as weight loss reduces cardiac demand and blood pressure settles. Users who don't lose much weight see less of the fade. Cardiac monitoring is essential at the high band.
Retatrutide: Deep Dives
Clinical Monitoring Framework
Clinical Evidence
Medical Disclaimer
The content in this GLP-1 comparison guide is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider before beginning any new protocol, supplement, or medication.