The short answer from the trials is about a fifth of body weight on the higher doses, for adults with obesity and without diabetes. That average hides a wide spread, and it took well over a year to reach.
This page sets out what the trials of tirzepatide measured: how much, how fast, for whom, and what happened when people stopped.
What SURMOUNT-1 measured
SURMOUNT-1 randomized 2,539 adults with a BMI of 30 or more, or 27 or more with a weight-related condition [2]. People with diabetes were excluded. Each got 5 mg, 10 mg or 15 mg weekly, or placebo, for 72 weeks.
Mean starting weight was 104.8 kg, and the dose was raised over the first 20 weeks. Everyone also got diet and activity counseling [1].
−15.0%
Mean weight change on 5 mg at week 72 (n = 630)
Jastreboff 2022
−19.5%
Mean weight change on 10 mg (n = 636)
Jastreboff 2022
−20.9%
Mean weight change on 15 mg (n = 630), vs −3.1% on placebo
Jastreboff 2022
At the trial’s mean starting weight, a 20.9% loss works out to roughly 22 kg, or about 48 pounds. That conversion is simple arithmetic on the average, not a figure the trial reported.
How the results were spread
A mean says little about any one person. The label reports what share of each group crossed each threshold [1].
| Weight lost | Placebo | 5 mg | 10 mg | 15 mg |
|---|---|---|---|---|
| 5% or more | 34.5% | 85.1% | 88.9% | 90.9% |
| 10% or more | 18.8% | 68.5% | 78.1% | 83.5% |
| 15% or more | 8.8% | 48.0% | 66.6% | 70.6% |
| 20% or more | 3.1% | 30.0% | 50.1% | 56.7% |
Read the other way, 9.1% of the 15 mg group did not reach a 5% loss. About 43% did not reach 20%. The trial also counted people who stopped the drug, so part of the shortfall is people who were no longer taking it.
Treatment was stopped because of side effects by 4.3%, 7.1% and 6.2% on the three doses, and 2.6% on placebo [2]. The side-effect record is set out in tirzepatide side effects.
With type 2 diabetes
The label’s second trial enrolled 938 adults with type 2 diabetes and a BMI of 27 or more [1]. At 72 weeks, weight fell 12.8% on 10 mg, 14.7% on 15 mg and 3.2% on placebo.
That is still a large loss, but about 5 to 6 points less than in the trial of people without diabetes.
How fast it comes off
The label starts at 2.5 mg for 4 weeks, then raises the dose in 2.5 mg steps at least 4 weeks apart [1]. Its half-life is 5 to 6 days, and steady levels are reached after 4 weeks at a dose.
The step schedule itself is covered in tirzepatide dosage. Two trials give a sense of pace once people are on it.
In SURMOUNT-4, 783 adults took the highest dose they tolerated, 10 or 15 mg, in an open-label phase [4]. The 670 who completed 36 weeks had lost 20.9% on average.
In a head-to-head trial against semaglutide, 44% on tirzepatide had lost 15% or more by week 24 [5]. On semaglutide, 21% had. Those fast responders were more likely to reach every threshold by week 72.
The semaglutide side of that timing is covered in how long semaglutide takes to work.
Does the weight stay off?
SURMOUNT-1 kept a subgroup of 1,032 people with prediabetes on treatment for 176 weeks, about 3.4 years [3]. Their weight change at that point was 12.3% on 5 mg, 18.7% on 10 mg and 19.7% on 15 mg, against 1.3% on placebo.
Fewer developed type 2 diabetes: 1.3% on tirzepatide against 13.3% on placebo (hazard ratio 0.07). That result applies to people with prediabetes, the group this extension followed.
What these numbers do not tell you
These trials used the brand product, alongside counseling on diet and activity. In SURMOUNT-1, 68% of participants were women, and people with diabetes were excluded [1].
Hair loss was among the side effects that tracked with weight loss, and it was more common in women. It is covered in semaglutide hair loss, which includes the tirzepatide label figures. For the direct comparison between the two drugs, see tirzepatide vs semaglutide.
To compare online prescribers, see the compounded tirzepatide rankings and the broader weight-loss peptide rankings.