Zepbound Timeline: Week by Week, What Changes and When
SURMOUNT-1 ran 72 weeks. By the end, people on tirzepatide 15 mg weekly had lost 20.9% of their body weight on average, against 3.1% on placebo. Side effects are most common in the first weeks and after each dose increase.
- Average loss, top dose
- 20.9%
- On placebo
- 3.1%
- Trial length
- 72 weeks
- Trial
- SURMOUNT-1
Zepbound: key facts
Its half-life runs 5 to 6 days. After 5.5 d, half is gone. Once five half-lives have passed (27.5 d), about 3% remains.
In SURMOUNT-1 over 72 weeks, people lost 20.9% of body weight, compared with 3.1% on placebo.
Prices in US dollars by month: the list price, plus self-pay offers, all taken from the maker's price page.
Sources: FDA label (DailyMed), Eli Lilly 1 2, cnbc.com.
Zepbound timeline: the numbers first
| Trial | Dose group | Average weight lost | Placebo or comparison | Weeks | Who was in it |
|---|---|---|---|---|---|
| SURMOUNT-1 | Tirzepatide 5 mg weekly | 15% | 3.1% | 72 | Adults with obesity or overweight, without diabetes |
| SURMOUNT-1 | Tirzepatide 10 mg weekly | 19.5% | 3.1% | 72 | Adults with obesity or overweight, without diabetes |
| SURMOUNT-1 | Tirzepatide 15 mg weekly | 20.9% | 3.1% | 72 | Adults with obesity or overweight, without diabetes |
| SURMOUNT-2 | Tirzepatide 10 mg weekly | 12.8% | 3.2% | 72 | Adults with obesity or overweight who also have type 2 diabetes |
| SURMOUNT-2 | Tirzepatide 15 mg weekly | 14.7% | 3.2% | 72 | Adults with obesity or overweight who also have type 2 diabetes |
| SURMOUNT-5 | Tirzepatide 10 or 15 mg weekly (Zepbound) | 20.2% | semaglutide (Wegovy) | 72 | Adults with obesity, without type 2 diabetes |
Studies cited: SURMOUNT-1 (FDA label (DailyMed)), SURMOUNT-2 (PubMed), and SURMOUNT-5 (PubMed).
In pounds, what the average means
Three starting weights had the trial average of 20.9% applied to them. This is a calculation, not a prediction for any one person. Some people lose more, while others lose less.
| Starting weight | Average loss on tirzepatide 15 mg weekly | Average loss on placebo |
|---|---|---|
| 180 lb | about 38 lb | about 6 lb |
| 220 lb | about 46 lb | about 7 lb |
| 260 lb | about 54 lb | about 8 lb |
Sources: FDA label (DailyMed).
Week by week
- In the early weeks, stomach side effects appear most often. The dose at that time is low and still climbing. After each dose increase, these effects often return for a few days.
- At Week 72, SURMOUNT-1 ends. This trial produced the average loss shown above.
Sources: health.clevelandclinic.org, FDA label (DailyMed).