Peptydy na odchudzanie — Tyrzepatid vs Retatrutide | PEPTEX
Opublikowano: 2026-04-05 14:20:00 | PEPTEX Research
✓ Reviewed by: Eskina Yulia — Endocrinologist · April 2026
Weight-loss peptides are the fastest-growing category in modern obesity pharmacology. Over the past five years the GLP-1 agonist class and its dual and triple analogues have completely reshaped what is achievable without bariatric surgery. Semaglutide, tirzepatide, retatrutide and cagrilintide show 15-25% body-weight loss over 68-72 weeks in clinical trials — a result that seemed impossible a decade ago. This guide walks through the molecule hierarchy, real SURMOUNT-1, STEP-1 and retatrutide phase-2 data, titration protocols, side-effect mitigation, muscle and skin preservation, stacks with ipamorelin, GHK-Cu, AOD-9604 and MOTS-C, plus myths, FAQ and concrete recommendations by goal type.
What GLP-1 peptides are and why they work
GLP-1 (glucagon-like peptide 1) is an incretin hormone released by intestinal L-cells in response to food. Modern analogues mimic it with a modified structure resistant to DPP-4, extending half-life from 2 minutes (native) to 5-7 days PubMed 31705817. Weight loss is delivered through three mechanisms. First, central appetite suppression via hypothalamic and brainstem GLP-1 receptors PubMed 26284720. Second, slowed gastric emptying, extending fullness by 2-4 hours. Third, improved insulin sensitivity and glucose-dependent insulin release. Net behavioural effect: spontaneous 500-700 kcal/day reduction without willpower. Bonus: semaglutide reduced major cardiovascular events by 20% in large outcome trials PubMed 34506739. See GLP-1 for longevity.
GLP-1 hierarchy by effect size
| Class | Molecule | Receptors | Peak loss | Horizon |
|---|---|---|---|---|
| Mono | Semaglutide | GLP-1 | 14.9% | 68 weeks |
| Mono (older) | Liraglutide | GLP-1 | 7-8% | 56 weeks |
| Dual | Tirzepatide | GLP-1 + GIP | 20.9% | 72 weeks |
| Triple | Retatrutide | GLP-1 + GIP + Glucagon | 24.2% | 48 weeks |
| Amylin | Cagrilintide | Amylin | 10.8% mono | 26 weeks |
| Dual amylin + GLP-1 | Cagrisema | GLP-1 + Amylin | 15.6-22.7% | 68 weeks |
Deeper pairwise comparisons in Tirzepatide vs Retatrutide, Cagrilintide vs Tirzepatide and Cagrilintide vs Mazdutide.
Semaglutide — the classic GLP-1
Semaglutide (Ozempic for type-2 diabetes, Wegovy for obesity) was the first GLP-1 to go mainstream. STEP-1 (Wilding 2021, n=1961, BMI >30 without diabetes) showed 14.9% weight loss on 2.4 mg/wk vs 2.4% placebo PubMed 33567185. STEP-5 confirmed durability to 104 weeks PubMed 34706206, and STEP-8 showed near-double the effect of liraglutide PubMed 34706207. Standard titration: 0.25 → 0.5 → 1 → 1.7 → 2.4 mg, four weeks per step. Predictable, well-studied, but lower ceiling — 30-40% plateau at 10-12% by week 40.
Tirzepatide — dual agonist king
Tirzepatide (Mounjaro, Zepbound) is the first clinically registered GIP/GLP-1 co-agonist. Added GIP activity delivers +5-7% more loss than pure GLP-1 via enhanced thermogenesis and adipose lipolysis. SURMOUNT-1 (Jastreboff 2022, n=2539) showed 20.9% loss at 72 weeks on 15 mg vs 3.1% placebo PubMed 35658024, with 57% of patients losing >20% and 36% >25%. See AOD-9604 vs Tirzepatide.
Titration schedule
| Weeks | Dose | Cumulative loss | Typical feel |
|---|---|---|---|
| 1-4 | 2.5 mg | 1-3 kg | Mild nausea days 1-3, appetite drop from day 5 |
| 5-8 | 5 mg | 3-6 kg | Stable small-portion satiety |
| 9-12 | 7.5 mg | 6-10 kg | New food habits forming |
| 13-16 | 10 mg | 10-13 kg | Visible body-comp change |
| 17-20 | 12.5 mg | 13-16 kg | Pace slows but continues |
| 21-72 | 15 mg | 16-25 kg | Plateau, nutrition and training tune-up |
When NOT to raise the dose
If nausea is marked, hold the step 6-8 weeks instead of 4. Many see 5 mg results equal to 10 mg — max dose isn't always needed. Raise only if side effects are minimal and loss slows below 0.3 kg/week.
Where and when to inject
Subcutaneous abdomen, thigh or upper arm, once weekly, same day. Morning before food is ideal. Pens dose precisely and painlessly — see PEPTEX pens.
Retatrutide — triple-agonist record holder
Retatrutide is the first molecule to activate GLP-1, GIP and glucagon. The glucagon arm lifts energy expenditure 10-15% via brown-fat and hepatic thermogenesis. Phase 2 (Jastreboff 2023, n=338) showed 24.2% loss at 48 weeks on 12 mg PubMed 37366315. Glucagon activity can transiently raise glucose — monitor 6-8 weeks. Ret + MOTS-C + NAD+ stack is detailed in Retatrutide stack.
Cagrilintide — amylin analogue for stacking
Cagrilintide is a long-acting amylin analogue signalling via area postrema — a separate satiety pathway from GLP-1. Phase 2 showed 10.8% mono-loss at 26 weeks PubMed 33795247; combined with semaglutide it hit 15.6-17.1% at 32 weeks PubMed 35939312. Full review: Cagrilintide amylin analogue.
AOD-9604 and MOTS-C — non-GLP-1 alternatives
Not everyone is a GLP-1 candidate. For contraindications (pancreatitis, MEN2, intolerance) or pure fat-loss without appetite suppression, alternatives exist. AOD-9604 is a GH fragment 176-191 stimulating lipolysis without IGF-1 impact PubMed 11602048; modest 3-5% over 12 weeks — see AOD-9604 honest review. MOTS-C is a mitochondrial peptide activating AMPK PubMed 25738459 — see MOTS-C and AMPK and MOTS-C mitochondrial peptide. 5-Amino-1-MQ vs AOD-9604 comparison — here. Full non-GLP-1 roundup: Peptides for fat burning.
Comparison table
| Peptide | Frequency | Weight loss | Muscle / skin | Nausea risk | Best for |
|---|---|---|---|---|---|
| Semaglutide | 1×/week | 14-17% | Moderate losses | Medium | Beginners, BMI 27-32 |
| Tirzepatide | 1×/week | 20-22% | Moderate losses | Medium | Most, BMI 30-40 |
| Retatrutide | 1×/week | 24-27% | Higher at fast pace | High | Severe obesity, BMI >35 |
| Cagrilintide | 1×/week | 10-11% | Minimal | Low | Soft start, stacking |
| AOD-9604 | 5×/week | 3-5% | None | None | Localised fat, support |
| MOTS-C | 2-3×/week | Metabolic | None | None | Insulin resistance |
Week-by-week expectations
| Weeks | Dose | Weight | Loss | Key focus |
|---|---|---|---|---|
| 0 | — | 95.0 kg | — | Baseline BMI, waist, fasting glucose |
| 4 | 2.5 mg | 93.0 | 2 kg | Nausea settles, appetite stable |
| 12 | 7.5 mg | 88.5 | 6.5 kg | Add strength 2-3×/wk |
| 24 | 12.5 mg | 82.0 | 13 kg | Protein 1.8 g/kg, check hair/skin |
| 48 | 15 mg | 76.0 | 19 kg | Add ipamorelin + GHK-Cu if needed |
| 72 | 15 mg | 74.5 | 20.5 kg | Transition to maintenance dose |
Side effects and mitigation
| Effect | Frequency | When | Mitigation |
|---|---|---|---|
| Nausea | 30-45% | Days 1-3, weeks 1-4 | Small portions, avoid fatty/sugary days 1-2 |
| Constipation | 15-25% | Week 2-8 | +25% water, 30 g fibre, ma... PEPTEX dostarcza do Polski — szybka wysyłka, certyfikowana jakość, darmowa dostawa od 150 €. Czytaj więcej: Peptydy na odchudzanie — Tyrzepatid vs Retatrutide | PEPTEXArticlesВведите корректный email
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