Eli Lilly's orforglipron, a once-daily oral non-peptide GLP-1 receptor agonist, met its primary endpoint in ATTAIN-1, a 72-week Phase 3 trial in adults with obesity (or overweight with a weight-related condition) and without diabetes. Full results were published in the New England Journal of Medicine on September 16, 2025.
The trial randomized 3,127 participants to orforglipron 6 mg, 12 mg, or 36 mg once daily, or placebo, alongside diet and activity counseling. At 72 weeks, mean body-weight change was -7.5% at 6 mg, -8.4% at 12 mg, and -11.2% at 36 mg, versus -2.1% for placebo (p<0.001 for all comparisons). At the highest dose, 59.6% of participants lost at least 10% of body weight and 39.6% lost at least 15%.
What draws attention to orforglipron is the oral, small-molecule format: unlike semaglutide or tirzepatide it is not a peptide, so it does not require injection and has no food or water intake restrictions, which could ease manufacturing scale and access. The weight loss reported here is more modest than the roughly 15-20% seen with high-dose injectable incretins in their own trials, though cross-trial comparisons are unreliable.
The safety profile was consistent with the GLP-1 class. Gastrointestinal adverse events (nausea, vomiting, diarrhea, constipation) were the most common and were generally mild to moderate. Lilly has said it is pursuing global regulatory submissions for orforglipron in obesity; the drug is not approved. As an oral incretin it also carries the same open questions as the rest of the class around lean-mass loss and weight regain after stopping.