Zepbound Results: What the Label's Clinical Studies Report

Zepbound is an FDA-approved prescription product that contains tirzepatide. Eli Lilly and Company makes it. Its label, the prescribing information published on DailyMed, reports the results of its clinical studies in section 14, and this guide reads that section.

Every fact below comes from the Zepbound label as published on DailyMed, updated August 28, 2026, and read through FDA's openFDA service on September 29, 2026, or from FDA's Drugs@FDA records read the same day. Quotes are word for word. The label prints the brand name in capital letters, and the quotes keep that. The label names its trials Study 1 to Study 6, each with a ClinicalTrials.gov number, and this page uses the label's names.

What this guide covers:

• What the Zepbound studies measured, and who took part
• The weight figures section 14 prints, quoted with table number and date
• Whether everyone in the studies lost weight
• What the label says, and does not say, about how long Zepbound takes to work
• How the label describes the way Zepbound works
• What the sleep apnea studies reported
• What the results do not tell you about any one person

These results describe the FDA-approved product in its trials; they do not describe compounded preparations.

The study groups in the label differ in strength. This page does not reprint strengths, amounts or schedules; they belong to the label itself and to the physician who reads it with you.

What did the Zepbound clinical studies measure?

Section 14 of the label describes six studies, and each one compared Zepbound with placebo. Four are in section 14.1, about weight reduction. Two are in section 14.2, about obstructive sleep apnea.

Section 14 of the Zepbound label names the primary measures of Studies 1 and 2 as "mean percent change in body weight and the percentage of patients achieving ≥5% weight reduction from baseline". In plain words: how much weight each group lost on average, and how many people reached a set amount.

Every group in these studies, placebo included, also followed a lifestyle program. For the first two studies, the label says: "In Studies 1 and 2, all patients received a standard lifestyle intervention which included instruction on a reduced-calorie diet". For the sleep apnea studies, the label says "all patients received instruction on a reduced-calorie diet and increased physical activity counseling throughout the study."

How much weight did people lose in the Zepbound studies?

Section 14 of the label sums up Studies 1 and 2 in one line: "After 72 weeks of treatment, ZEPBOUND resulted in a statistically significant reduction in body weight compared with placebo". Put simply, the groups taking Zepbound lost more weight on average than the groups taking placebo, and the difference passed the studies' statistical tests.

The table gives the average change the label prints for each group. The arms differ in strength, and this page does not reprint strengths; read Table 2 in the label for them. The Zepbound cells appear in the same order as the label's columns. A minus sign marks a decrease from the starting point.

Study 3 had a different design. Section 14 of the Zepbound label states: "Only patients who lost ≥5% body weight during the 12-week intensive lifestyle lead-in period entered the 72-week randomized treatment period." So Study 3 counted change from the day of randomization, in people who had already lost weight with an intensive lifestyle program. Its figures start from a different point than those of Studies 1 and 2.

These figures are group averages. The label also reports that some people in every group of Studies 1, 2 and 3, placebo included, stopped the study drug before the end, and that the final weight was missing for some people. It explains how those gaps were handled: "The missing values were imputed by a hybrid approach using retrieved dropouts from the same treatment group".

So does Zepbound work? In the label's terms, the question the weight studies answered was whether the groups taking Zepbound lost more weight on average than the groups taking placebo, and section 14 reports that they did. The label does not predict what will happen for any one person.

Did everyone in the studies lose weight?

The label does not say that everyone lost weight. Section 14 answers the question with shares: the percentage of people in each group who reached at least a set amount of weight reduction. The label measured the same shares in the placebo groups, and some people taking placebo reached each threshold too.

Each share describes a group, so none of them is the chance for one person. The label also marks some comparisons in Table 2 "Not controlled for type I error rate", a statistical qualifier its footnotes explain.

The label also looked at subgroups. Section 14 of the Zepbound label states: "A reduction in body weight was observed with ZEPBOUND irrespective of age, sex, race, ethnicity, baseline BMI, and glycemic status." That sentence is about groups defined by those traits, not about each person.

How long does it take for Zepbound to work, according to the label?

People often ask how long Zepbound takes to work. The label does not give a point at which Zepbound starts working for a person. It reports what each study measured at its end. Section 14 of the label describes Study 1 and Study 2 each as "a 72-week trial", Study 3 as "an 84-week trial with a 12-week intensive lifestyle intervention lead-in period", and Studies 5 and 6 as trials "of 52 weeks duration".

Section 14 also contains charts of the average change over time in each group, such as Figure 3 for Study 1. This page does not reprint values read off those charts. An average curve for a group does not tell any one person when a change will appear.

What the label does describe is how long tirzepatide stays in the body. Section 12.3 of the Zepbound label states: "The elimination half-life is approximately 5-6 days in patients with overweight or obesity, and in patients with OSA and obesity." Half-life describes how the body clears a drug. It is not a measure of when results appear. For more on clearance, see how long tirzepatide stays in your system.

How a person is doing is reviewed by the prescriber at each visit. Questions about timing and progress belong in that conversation.

How does Zepbound work, according to the label?

Section 12.1 of the label, "Mechanism of Action", explains it in a few sentences. It opens: "Tirzepatide is a GIP receptor and GLP-1 receptor agonist." It continues: "Tirzepatide selectively binds to and activates both the GIP and GLP-1 receptors, the targets for native GIP and GLP-1."

The label calls the body's own versions "native GIP and GLP-1". It then links them to appetite:

• "GLP-1 is a physiological regulator of appetite and caloric intake."
• "Nonclinical studies suggest the addition of GIP may further contribute to the regulation of food intake."
• "Both GIP receptors and GLP-1 receptors are found in areas of the brain involved in appetite regulation."

Section 12.1 also explains why the drug lasts in the body: "It contains a C20 fatty diacid that enables albumin binding and prolongs the half-life."

Section 1 sets this inside the approved use: Zepbound is used "in combination with a reduced-calorie diet and increased physical activity". For how the same molecule is described on the Mounjaro label, see Zepbound vs Mounjaro.

What did the sleep apnea studies report?

Studies 5 and 6 studied Zepbound in adults with moderate to severe obstructive sleep apnea (OSA) and obesity. Study 5 enrolled people who "were unable or unwilling to use Positive Airway Pressure (PAP) therapy". Study 6 enrolled people "who were on PAP therapy". The main measure was the apnea-hypopnea index (AHI), which the label reports in events per hour.

The label sums up both studies this way: "In Studies 5 and 6, treatment with ZEPBOUND for 52 weeks resulted in a statistically significant reduction in AHI compared with placebo, and greater proportions of patients treated with ZEPBOUND achieved remission or mild non-symptomatic OSA compared to placebo."

In Table 9 the Zepbound column headings also name strengths; this page does not reprint them. The AHI rows are changes in events per hour, not percentages. ESS stands for the Epworth Sleepiness Scale.

One limit matters to anyone who uses a PAP machine. The label states: "The clinical studies for OSA did not evaluate the timing or appropriateness of PAP discontinuation in patients who were previously compliant with PAP therapy." In plain words, the studies do not tell anyone whether or when to stop PAP. That decision belongs to the clinician who treats the sleep apnea.

Do these results apply outside the trials?

Section 14 describes the FDA-approved Zepbound product in its own trials. Those trials had entry rules, a lifestyle program for every group and a fixed length. The label does not say what any one person outside them will see.

Some limits come straight from the label:

• Studies 1 and 3 and the two sleep apnea studies left out people with type 2 diabetes. For the sleep apnea studies the label says: "Patients with type 2 diabetes mellitus were excluded".
• The studies enrolled adults. Section 8.4 says: "The safety and effectiveness of ZEPBOUND have not been established in pediatric patients."
• The results come with a lifestyle program, because section 1 pairs Zepbound with "a reduced-calorie diet and increased physical activity".

This page also leaves parts of section 14 out on purpose:

• Study 4, the "randomized withdrawal trial", is not reprinted. Its design answers a different question, and its figures are easy to misread out of context. Read it in section 14.1 of the label.
• The label's tables of waist size, blood pressure, cholesterol and other cardiometabolic measures are not reprinted.
• Strengths, amounts and schedules are not reprinted anywhere on this page.

The label also reports side effects in its own sections. For those, see Zepbound side effects.

Who decides whether Zepbound is appropriate?

A licensed physician does. The prescribing information is written for health care professionals, and Zepbound also comes with a Medication Guide written for patients. Medication is prescribed only if a licensed physician determines it is appropriate, and the answer can be no.

Useful questions for that conversation:

1. Does section 1 of the label describe my situation?
2. Does the boxed warning, titled "WARNING: RISK OF THYROID C-CELL TUMORS", or anything in section 4 apply to me or my family history?
3. Which warnings in section 5 matter for my health history?
4. How will we judge whether it is working for me, and what will we review at each visit?
5. I take other medicines. Does anything in the label apply to them?

Where can you read section 14 yourself?

The label is public and free to read.

1. Open DailyMed, the National Library of Medicine's label library, and search for Zepbound.
2. Check the set id: 487cd7e7-434c-4925-99fa-aa80b1cc776b.
3. Note the "updated" date on the page. On September 29, 2026, DailyMed showed August 28, 2026.
4. Scroll to section 14, "Clinical Studies", and read Tables 2, 4 and 9 with the footnotes under each.
5. For the approval history, search Drugs@FDA for NDA 217806.

For help with the layout of a label, see how to read a prescription label.

What the primary sources say

• Eli Lilly and Company via DailyMed, Zepbound (tirzepatide) prescribing information, set id 487cd7e7-434c-4925-99fa-aa80b1cc776b, updated August 28, 2026 (accessed September 29, 2026): "After 72 weeks of treatment, ZEPBOUND resulted in a statistically significant reduction in body weight compared with placebo"; "A reduction in body weight was observed with ZEPBOUND irrespective of age, sex, race, ethnicity, baseline BMI, and glycemic status."; "In Studies 5 and 6, treatment with ZEPBOUND for 52 weeks resulted in a statistically significant reduction in AHI compared with placebo"; "GLP-1 is a physiological regulator of appetite and caloric intake."; "The safety and effectiveness of ZEPBOUND have not been established in pediatric patients."
• U.S. Food and Drug Administration, openFDA drug label API, Zepbound label version 40, effective August 28, 2026 (accessed September 29, 2026): the same label text, word for word, including section 14, "Clinical Studies", with Table 2, Table 4 and Table 9; the trials are named "Study 1" to "Study 6" with ClinicalTrials.gov numbers.
• U.S. Food and Drug Administration, Drugs@FDA application data through openFDA, NDA 217806 (accessed September 29, 2026): Zepbound, sponsor "ELI LILLY AND CO", original approval 11/08/2023.

Every source is listed with its address below.

This article is for informational purposes only and does not constitute medical advice. Medication is prescribed only if a licensed physician determines it is appropriate. Label sentences and figures are quoted word for word from the FDA-approved prescribing information named above, as published on DailyMed on the date shown. Labels change, so read the current label and the Medication Guide that came with your own medicine.

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