Research use only · Not for human consumptionPepwizard compares vendor pricing for research-grade compounds. Nothing on this site is medical advice. How we price.
Modern Fat Loss Stack
The two incretin-based therapies driving the modern weight-loss revolution — semaglutide as the accessible default, tirzepatide as the higher-efficacy option.
- Duration
- 12+ months
- Experience
- beginner
Peptides in this stack
Semaglutide
A GLP-1 receptor agonist originally approved for type 2 diabetes and now widely used for chronic weight management, producing 15%+ reductions in body weight over 12 months in clinical trials.
Tirzepatide
A dual GIP and GLP-1 receptor agonist producing the largest sustained weight reductions of any drug currently licensed, averaging 20–22% body weight loss in clinical trials.
This isn't really a "stack"
Unlike research-peptide stacks where compounds are combined, the fat-loss decision is either/or. You pick one GLP-1 agent and titrate it. Combining GLP-1 drugs is not clinically validated and significantly increases GI side-effect risk.
Choosing between them
| Factor | Semaglutide (Wegovy) | Tirzepatide (Mounjaro) |
|---|---|---|
| Mean weight loss | ~15% over 68 weeks | ~20% over 72 weeks |
| Head-to-head | Baseline | Superior in SURMOUNT-5 |
| UK NHS access | Tightly controlled | Expanded 2025 |
| Private cost | £150–£250/month | £150–£200/month |
| Mechanism | GLP-1 only | Dual GIP/GLP-1 |
For most people starting out, tirzepatide is the rational choice given superior efficacy at similar cost and tolerability. Semaglutide remains a strong option for those already stable on it or where supply is an issue.
What comes next
- Retatrutide (Phase 3): triple agonist with ~24% weight loss in Phase 2. Expected approval 2027+.
- Oral GLP-1s: Rybelsus (oral semaglutide) exists but has much lower bioavailability. Orforglipron is a non-peptide oral GLP-1 in late-stage development.
Practical considerations
- Plan for 4–6 months of titration to reach therapeutic dose.
- GI side effects are worst during titration and usually settle.
- Discontinuation without lifestyle change leads to weight regain — plan for long-term use or a structured taper with dietary and resistance-training support.
- Lean mass preservation matters: pair with adequate protein (≥1.6 g/kg) and resistance training.