Tirzepatide activates GIP and GLP-1 receptors. It affects glucose regulation and food intake. Mounjaro and Zepbound contain the same active compound with different labeled uses. Mounjaro is used for type 2 diabetes. Zepbound is used for chronic weight management and obstructive sleep apnea in specified populations.[1.1][1.2]
One selected study: Randomized trial comparing tirzepatide with placebo for cardiovascular death or worsening heart failure, and patient-reported health status. 731 people with obesity and heart failure with preserved ejection fraction; median follow-up was 104 weeks, with health-status assessment at 52 weeks. A verified dose and schedule have not yet been added to this study summary. The first primary outcome occurred in 9.9% versus 15.3%. Worsening heart failure occurred in 8.0% versus 14.2%; cardiovascular deaths were 2.2% versus 1.4%. The other primary outcome, health-status score, improved 19.5 versus 12.7 points. Adverse events, mainly digestive, led to stopping treatment in 6.3% versus 1.4%. Study limitations were not stated in the abstract. Methodological quality has not been appraised.[2.1]
Studied methods, not dosing advice. Selected evidence, not a complete literature review or formal quality appraisal. Read the study summary
Source scope is listed with each reference. Prepared by PED Evidence with AI assistance. Independent clinician review has not been completed. Review standards
Evidence summarized on PED Evidence
45 completed summaries
28 human-study reports
17 randomized-trial candidates
13 safety-topic reports
These counts describe completed summaries on this site, not the size of the full literature. Publications can share participants; design labels are discovery metadata, not appraisals.
At 72 weeks, fat mass fell 33.9% and lean mass 10.9% with pooled tirzepatide doses, versus 8.2% and 2.6% with placebo. About a quarter of the weight lost was lean mass in both groups.
Limitations & adverse findings
Both fat and lean mass declined. These results do not establish muscle preservation.
What might this mean? · interpretation
The proportion of weight loss attributed to lean mass differs from the percentage of starting lean mass lost.
What might this mean, and what would change the interpretation?
DXA lean mass is not a direct measure of contractile muscle or strength. This was a 160-person substudy, not the full randomized population.
What would clarify this: Muscle function, regional muscle measures and longer-term follow-up.
Findings reviewed · abstract
Checked Sep 15, 2026 against the linked abstract. This reading note is not a formal risk-of-bias appraisal.
The source links a published correction (DOI 10.1111/dom.70050). The figures below come from the current abstract; the full correction text has not been checked.
At 72 weeks, fat mass fell 33.9% and lean mass 10.9% with pooled tirzepatide doses, versus 8.2% and 2.6% with placebo. About a quarter of the weight lost was lean mass in both groups.
Limits & adverse findings: DXA lean mass is not a direct measure of contractile muscle or strength. This was a 160-person substudy, not the full randomized population. Both fat and lean mass declined. These results do not establish muscle preservation.
Mounjaro is used for type 2 diabetes. Zepbound is used for chronic weight management and obstructive sleep apnea in specified populations. [1][2]
Known half-life
About 5 days in the Mounjaro label; about 5–6 days in the Zepbound label for people with overweight or obesity, including obstructive sleep apnea populations. [1][2]
Half-life describes how quickly the measured drug concentration falls by half. It does not set a dosing interval.
Evidence & important limits
Benefits and eligibility depend on the indication and population. The labels include gastrointestinal effects, pancreatitis warnings and a boxed warning about thyroid C-cell tumors observed in rats. [1][2]
Safety & evidence boundaries
Source-specific information, not a personal safety clearance or monitoring plan.
Benefits and eligibility depend on the indication and population. The labels include gastrointestinal effects, pancreatitis warnings and a boxed warning about thyroid C-cell tumors observed in rats.
Interactions, rare harms, long-term effects and reversibility require separate evidence. Do not infer they are absent when the sources here do not address them.
Identity, names & formulations
Canonical compound: Tirzepatide · tirzepatide
Searchable names: LY3298176, Mounjaro, Zepbound
Names share a parent research page. Different esters, salts, routes and brands are not assumed to have the same half-life, indication or exposure.
Combination evidence stays attached to the studied combination. It is not automatically assigned to each ingredient.
Understand the evidence types
Read the model and design first, then the population, outcome and limitations. These categories describe evidence, not a best-compound ranking.
Randomized human trials
Compare assigned interventions. Randomization does not by itself establish low bias or relevance to every population.
Controlled human studies
Use a comparison group; allocation and confounding still matter.
Prospective human research
Follows participants forward. It may be observational or interventional, so this is not a separate quality grade.
Observational human research
Describes associations. Confounding can explain differences.
Case reports and series
Useful for unusual events and safety signals, not reliable rates or effect sizes.
Animal research
Can test biology and function in a living model. Human exposure, benefit and safety remain separate questions.
Cell and tissue research
Tests responses in a preparation, including human-derived cells. It is not a human participant trial.
Mechanistic and computational evidence
Helps explain or predict a pathway; predictions need experimental and clinical testing.
Anecdotal reports
Self-reported experiences can generate questions. Product identity, selection bias and other interventions may be uncontrolled.
Systematic reviews synthesize studies and depend on their quality. Preprint status and abstract versus full-paper reading are separate labels. Citation popularity measures attention, not reliability. A study summary is not a formal quality appraisal.
Reference facts checked 2026-09-16. Source scope is listed above; this is not a formal quality appraisal. See each label for full prescribing information.