Semaglutide vs tirzepatide: which GLP-1 peptide wins for weight loss?
Tirzepatide outperforms semaglutide in head-to-head weight loss trials — but the right choice depends on more than raw numbers.
by Editorial team
The trial data
In SURMOUNT-1 (tirzepatide) and STEP trials (semaglutide), tirzepatide produced roughly 5–7 percentage points more body weight reduction at comparable timeframes. The SURPASS-2 head-to-head trial confirmed tirzepatide's edge in type 2 diabetics.
Tirzepatide's dual mechanism (GLP-1 + GIP) is the leading explanation. GIP appears to enhance the satiety and metabolic effects beyond GLP-1 alone.
Side effects: similar but not identical
Both share GI side effects in the first 4–6 weeks. Tirzepatide users sometimes report slightly higher rates of constipation; semaglutide users sometimes report more reflux. Slow titration matters more than the choice itself.
Real-world choice factors
Cost and access vary significantly by country and insurance. Semaglutide has been on the market longer and is generally easier to get. Tirzepatide is newer, often pricier, and supply has fluctuated.
For people who plateau on semaglutide, switching to tirzepatide is the most common next step.