What the trial was testing
The trial enrolled 114 patients with obesity. The study was sponsored by Eli Lilly and Company and tracked outcomes across the full group of patients who matched the trial's eligibility profile.
It was an early-stage trial — researchers are still confirming safety and getting an early look at how well the treatment works. Trials at this stage are designed to produce evidence regulators and physicians can act on — not just observations to follow up later.
What the results showed
Tirzepatide reduced lunch intake by 525 calories compared to placebo after three weeks.
Nature medicine · 2025 · NCT04311411
These findings — that people ate over 500 fewer calories at lunch after three weeks on tirzepatide — were published in the Nature medicine and represent the headline result of the study.
Researchers tracked outcomes across 114 patients enrolled in the trial. The result was consistent enough across the group that the team felt confident reporting it.
What this means for patients
For patients with obesity, this result changes the calculus on what to ask their care team about. Whether it changes day-to-day care depends on factors like disease subtype, prior treatments, and where the patient is in their care journey.
What you can do now
This was an early-stage study and the treatment is not yet FDA-approved for this specific use. Tirzepatide (Mounjaro) is FDA-approved for type 2 diabetes, and a similar formulation (Zepbound) is approved for weight management. Ask your doctor whether tirzepatide might be right for you.
Eligibility for the treatments mentioned above depends on specific test results and clinical history. Bring this summary, the trial name, and your most recent labs or pathology report to your next visit.
Open obesity trials
Resistance Training to Prevent Muscle Loss During Treatment With Tirzepatide
Incretin-based pharmacotherapies induce significant weight loss and represent a paradigm shift in obesity treatment. However, particularly fast weight loss may be accompanied by a significant loss of muscle mass, which is associated with a reduced metabolic rate at rest and during physical activity, increased insulin resistance, limited mobility, and potential long-term adverse effects. The aim of this clinical trial is to examine the effects of resistance training versus standard of care on contractile thigh muscle volume in patients receiving the dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonists 'tirzepatide'.
Knee Injections for Obese Patients With Knee Arthritis
The purpose of this study is to assess obese patients with knee arthritis and determine the non-inferiority of a low dose steroid treatment vs. standard dose steroid treatment for two knee outcome measures: pain and function.