Tirzepatide Weight Loss: What the Trials Measured
How much Tirzepatide weight loss did trials find?
SURMOUNT-1 weighed 2,539 adults for 72 weeks. At the top dose, average change was -20.9%. The placebo group changed by -3.1% [4]. Both minus signs mean weight fell.
SURMOUNT-5 was a 2025 direct comparison of 751 adults. Tirzepatide brought -20.2%, while the other drug brought -13.7% over the same 72-week span [5]. Again, the minus signs show a drop.
Your scale may move more, less, or not at all. Next comes the split between fat and muscle. You’ll also see the results after people ended the drug.
You’ll get a guide from these averages, but you won’t get a promised result.
What did SURMOUNT-1 and SURMOUNT-5 find about Tirzepatide?
SURMOUNT-1 followed 2,539 adults with obesity in 2022. None had type 2 diabetes. Body mass index sets weight beside height. It was 30 or more, or 27 with another weight-linked illness. People took 5, 10, or 15 mg for 72 weeks. Amounts rose during the first 20 weeks.
At 72 weeks, average Tirzepatide weight loss was:
- 5 mg: -15.0%, versus -3.1% with placebo
- 10 mg: -19.5%
- 15 mg: -20.9%
Each minus sign means weight went down. Stomach and bowel trouble came mainly while the amount rose. More tirzepatide users lost 10%, 15%, 20%, or 25% [4].
SURMOUNT-5 followed 751 adults with obesity in 2025. None had type 2 diabetes. They used 10 or 15 mg of tirzepatide. The other group used the highest amount each person could bear. That was another weekly shot. The study ran 72 weeks.
At 72 weeks, average change was -20.2% with tirzepatide. It was -13.7% with the other drug. The minus signs mean weight fell. Tirzepatide brought the clearly larger drop. Waists also shrank more. More people reached every loss mark from 10% to 25% [5].
A 2025 SURMOUNT-1 follow-up also watched adults with prediabetes. That means high blood sugar, but diabetes hasn’t begun. Their average weight stayed below the starting point. Fewer developed type 2 diabetes [28].
Start with your health to find the closest group.
Why can Tirzepatide lead to weight loss?
Two hormones leave your gut, and tirzepatide copies them. One is GLP-1. They act in your gut and brain. GLP-1 may ease hunger while food stays longer in your stomach.
The other may affect your brain and body fat. Together, they may change how much you eat and use for energy [1] [27]. People often describe fewer thoughts about food. In plain terms, they feel less hungry.
A review published in 2025 said GLP-1 and the other hormone may work in the brain, liver, and fat [27]. This could explain some of the weight change. Studies in people show how much weight moved.
Not all lost weight was fat. A 2025 study scanned 160 people. At 72 weeks, about 75% of the loss was fat. Muscle and other tissue made up about 25% [10]. Across a wider review, half the studies put muscle below 28% of lost weight, and half put it above [15]. Your scale can’t tell the two apart.
Your strength matters too. You can’t judge progress by weight alone.
Does Tirzepatide cut hunger, burn fat, or both?
The best answer is both, with stronger proof that people eat less. GLP-1, one copied hormone, lowers hunger. The other may raise the energy your body uses. Direct studies found more loss with the two-hormone drug. The other drug copied only GLP-1 [3] [5].
SURMOUNT-1 asked whether nausea explained the weight loss. People with stomach trouble and those without it lost similar amounts [35]. Feeling sick wasn’t the whole cause.
A 2025 follow-up studied 1,605 SURMOUNT-1 volunteers. Blood pressure and the three-month sugar reading improved. Their bodies also used insulin better. These gains changed most as weight loss rose from under 5% to 20%. Blood fats improved mainly after more than 10% loss [36]. These were group trends, not goals for you.
The scale may pause for several weeks. People report this on the tirzepatide side effects and Tirzepatide effects pages. Your body may adjust as you eat less. A pause alone doesn’t show failure.
Your blood pressure and blood tests can tell you more than the scale.
Why might Tirzepatide weight loss slow down?
SURMOUNT-1 reported an average -20.9% at 72 weeks. The minus sign means weight fell. Some people lost more, and some lost less.
Dose. In SURMOUNT-1, average change was -15.0% at 5 mg, -19.5% at 10 mg, and -20.9% at 15 mg. The label raises doses only as a person can bear them [4]. A larger dose isn’t right for everyone.
Time. Weight often fell faster early, then slowed. In 2023, people lost at least 5% through food and activity before the drug study. Only then did SURMOUNT-3 begin. Tirzepatide brought another -18.4% over 72 weeks [30]. That minus sign means another drop. A slow spell didn’t mean all loss had ended.
Stopping. SURMOUNT-4 gave the clearest test in 2024. People moved from tirzepatide to placebo and regained weight. Those who stayed on tirzepatide kept losing [14]. Studies treat the drug as lasting care rather than a short course.
You can check each paper on the Tirzepatide references page.
You’ll need follow-up to learn why your loss slowed.