If you're researching weight loss medication, you'll encounter two key drug names: semaglutide and tirzepatide. These are the active molecules behind the brand-name medications. Understanding them helps you make sense of the options.
Semaglutide (Wegovy, Ozempic)
Semaglutide is a GLP-1 receptor agonist — it mimics a single gut hormone (GLP-1) that reduces appetite, slows digestion, and regulates blood sugar. Developed by Novo Nordisk and first approved in 2017 for diabetes (Ozempic), then in 2021 for weight loss (Wegovy) at a higher dose.
- Single-target mechanism (GLP-1 only)
- Average weight loss: 15–17% at the 2.4mg dose
- Extensive safety data: 15,000+ trial participants, 4-year follow-up published
- Proven cardiovascular benefit (SELECT trial: 20% MACE reduction)
Tirzepatide (Mounjaro)
Tirzepatide is a dual GIP/GLP-1 receptor agonist — it targets two gut hormones simultaneously. Developed by Eli Lilly and approved in 2022 for diabetes, then for weight loss. The addition of GIP receptor activation appears to enhance fat metabolism and energy expenditure beyond what GLP-1 alone achieves.
- Dual-target mechanism (GLP-1 + GIP)
- Average weight loss: ~21% at the 15mg dose
- Newer molecule with less long-term data (2-year follow-up)
- Cardiovascular outcomes trial ongoing (SURPASS-CVOT)
Which molecule is better?
For pure weight loss, tirzepatide currently has the edge (~21% vs ~15-17%). For cardiovascular risk reduction, semaglutide has the proven data. Both are excellent medications that represent a genuine breakthrough in obesity treatment.
The good news: having two effective molecules means more options, more competition, and hopefully lower prices over time.