Tirzepatide Dosage: What the Trials Reported

What tirzepatide dosage did SURMOUNT-1 study?

SURMOUNT-1 tested three once-weekly maintenance doses, 5 mg, 10 mg, and 15 mg, against placebo (Jastreboff et al., NEJM 2022; doi:10.1056/NEJMoa2206038; PMID 35658024).

The trial enrolled adults with obesity, or with overweight plus a weight-related condition, and ran for 72 weeks. Each active arm reached its target dose after a slow step-up period. The table below shows the reported mean weight loss by arm.

The ranges below reflect what published studies and commonly studied research protocols report. This is educational, not a prescription or a personal recommendation.

Read this as a record of what the study measured, not a target for any one person.

Why is tirzepatide dosed once weekly?

Its long duration of action let the trials use a single subcutaneous dose per week, the schedule applied across the SURMOUNT and SURPASS programs (Jastreboff et al., NEJM 2022; Frías et al., NEJM 2021).

In SURMOUNT-1, participants received one injection each week for the length of the study (Jastreboff et al., NEJM 2022). The weekly schedule is a feature of how the compound was tested, not an instruction for readers.

How did the studied dose relate to weight loss?

Larger studied doses tracked with greater mean weight loss in SURMOUNT-1, rising from about 15 percent at 5 mg to up to about 22.5 percent at 15 mg (Jastreboff et al., NEJM 2022).

This dose-response pattern is why the 10 mg and 15 mg arms are cited so often. For context, semaglutide reached about 15 percent mean weight loss in the STEP 1 obesity trial (Wilding et al., NEJM 2021). A separate head-to-head trial, SURPASS-2, compared tirzepatide with semaglutide in adults with type 2 diabetes, not obesity, and reported larger reductions in blood sugar and body weight with tirzepatide (Frías et al., NEJM 2021; doi:10.1056/NEJMoa2107519; PMID 34170647).

How does tirzepatide dosage compare with semaglutide and retatrutide?

Across separate trials, tirzepatide's top studied arm reached up to about 22.5 percent, semaglutide reached about 15 percent, and retatrutide reached up to about 24.2 percent (Jastreboff et al., NEJM 2022; Wilding et al., NEJM 2021; Jastreboff et al., NEJM 2023).

These results come from different trials with different designs and populations, so they are not a clean apples-to-apples comparison. The one direct head-to-head, SURPASS-2, was run in people with type 2 diabetes and favored tirzepatide over semaglutide on blood sugar and weight (Frías et al., NEJM 2021).

What did research report about a step-up schedule?

The trials started participants at a low dose and raised it in steps over several weeks to reach the maintenance dose, an approach used to reduce gastrointestinal side effects (Jastreboff et al., NEJM 2022).

In SURMOUNT-1, participants began at 2.5 mg once weekly and moved up gradually toward their assigned maintenance dose (Jastreboff et al., NEJM 2022). Gastrointestinal events, such as nausea and diarrhea, were the most common adverse events reported, and they were usually mild to moderate (Jastreboff et al., NEJM 2022). How and whether to change a dose is a clinical decision, not something to copy from a trial protocol.

What happens to weight after stopping tirzepatide?

In SURMOUNT-4, people who stopped tirzepatide regained a large share of their lost weight, while those who continued kept losing (Aronne et al., JAMA 2024).

That withdrawal trial ran a 36-week open-label lead-in on tirzepatide, then randomized participants to continue or switch to placebo. Those who continued gained an additional mean reduction of about 5.5 percent, while those switched to placebo regained much of their earlier loss (Aronne et al., JAMA 2024; doi:10.1001/jama.2023.24945).

This mirrors what other work in the class reports. The STEP 1 trial extension found that participants regained about two-thirds of their lost weight in the year after semaglutide was withdrawn (Wilding et al., Diabetes Obes Metab 2022; doi:10.1111/dom.14725; PMID 35441470). Part of the reason is adaptive thermogenesis, the drop in energy use that follows weight loss and pushes the body toward regain (Rosenbaum and Leibel, Int J Obes 2010). Separate long-term data report that weight loss on GLP-1 therapy tends to reach a plateau over time rather than continuing without limit: in the two-year STEP 5 trial, semaglutide weight loss plateaued after about week 60 and held near 15.2 percent through week 104 (Garvey et al., Nat Med 2022; doi:10.1038/s41591-022-02026-4; PMID 36216945).

Is this tirzepatide dosage a recommendation for me?

No. The figures on this page describe what published trials reported, and any personal dose is a decision for a qualified clinician who knows your history.

Peptaralabs provides research material and educational summaries of the published record. Nothing here is medical advice, and none of it should be used to self-select a dose, a schedule, or a plan. To understand the broader class, see [what are peptides](/what-are-peptides).