Fat loss
Tirzepatide
A dual GIP/GLP-1 receptor agonist that generally outperforms semaglutide for weight loss in head-to-head trials. FDA-approved for type 2 diabetes and chronic weight management.
FDA-approved Fat loss
- Full name
- Tirzepatide (dual GIP/GLP-1 receptor agonist)
- Also known as
- Mounjaro (diabetes brand), Zepbound (weight-loss brand)
- Regulatory status
- FDA-approved prescription medication (Mounjaro for type 2 diabetes, Zepbound for chronic weight management).
Origin
A single synthetic peptide engineered to activate both the GIP and GLP-1 receptors, combining two incretin hormone pathways in one molecule, with a fatty-acid modification giving it a once-weekly half-life similar to semaglutide.
Mechanism
GLP-1 receptor activation provides the same appetite-suppression, gastric-emptying-delay and glucose-control effects as semaglutide. Added GIP receptor activation appears to enhance insulin sensitivity and may directly affect fat cell metabolism, thought to explain tirzepatide's larger average weight-loss effect in trials.
Research summary
Evidence
The SURMOUNT trial program showed average weight loss around 20-22% of body weight at the highest studied dose (15 mg/week) over 72 weeks in non-diabetic participants, meaningfully larger than semaglutide's ~15% in comparable trial designs. A head-to-head trial (SURMOUNT-5) found tirzepatide produced significantly more weight loss than semaglutide directly. Visceral fat reduction, measured via DXA scan substudies, showed roughly 40% reduction in visceral fat mass over the ~72-week SURMOUNT trial period.
Evidence tier: FDA-approved — see the methodology note for how this is assessed.
Citations
- Tirzepatide Once Weekly for the Treatment of Obesity — Jastreboff et al. 2022
- Tirzepatide for Obesity Treatment and Diabetes Prevention — Jastreboff et al. 2024
Reported benefits
- Larger average weight loss than semaglutide in head-to-head and cross-trial comparison
- Strong visceral fat reduction specifically (measured via imaging in trial substudies)
- Improved glycemic control in type 2 diabetes, generally considered at least as effective as semaglutide for this indication
Dosing protocols reported in the literature & community
These are protocols reported by compounding pharmacies, published trials, or self-experimentation communities — not a prescription. Start low, especially for anything new.
| Route | Reported protocol |
|---|---|
| Subcutaneous injection, once weekly (standard prescribed titration) | Starting dose 2.5 mg/week for 4 weeks, then increasing in 2.5 mg increments roughly every 4 weeks as tolerated, up to a maximum studied/approved dose of 15 mg/week. |
Side effects
- Similar GI side-effect profile to semaglutide: nausea, diarrhea, vomiting, constipation, most pronounced during dose escalation
- Same boxed warning regarding thyroid C-cell tumor risk based on rodent data
- Lean mass loss alongside fat loss, same caveat as semaglutide regarding resistance training and protein intake
- Not recommended with personal/family history of medullary thyroid carcinoma or MEN 2
Safety notes
Community & reddit notes (anecdotal — not clinical evidence)
Generally reported as more potent than semaglutide for both appetite suppression and weight loss, sometimes at the cost of more pronounced GI side effects during titration. A frequent discussion point is trading off tirzepatide's stronger effect against semaglutide's gentler side-effect profile for people sensitive to GI symptoms.
Related peptides
Mixing compatibility
Pulled from a community-charted mixing-compatibility reference (anecdotal, clinic-use, and community-reported signals) — not a safety guarantee. Verify independently before combining anything.