Orforglipron delivers 27.3 pounds of average weight loss in its first pivotal obesity trial

Eli Lilly reported topline results on Aug. 7, 2025, from ATTAIN-1, the first of two pivotal Phase 3 trials of orforglipron, an investigational once-daily oral GLP-1 receptor agonist, in adults with obesity or overweight who do not have diabetes ^[1]. At 72 weeks, the highest dose lowered body weight by an average of 12.4% — about 27.3 pounds — compared with 0.9% (2.2 pounds) on placebo, using what the company calls the efficacy estimand ^[1].

The trial randomized 3,127 participants across the U.S., Brazil, China, India, Japan, South Korea, Puerto Rico, Slovakia, Spain and Taiwan to 6 mg, 12 mg or 36 mg of orforglipron or placebo ^[1]. Average starting weight was 103.2 kg (227.5 lbs) with an average BMI of 37.0 ^[1]. Participants had a BMI of at least 30, or at least 27 with a weight-related condition such as high blood pressure, abnormal cholesterol, obstructive sleep apnea or cardiovascular disease ^[1].

What the numbers show

Average weight loss rose with dose: 7.8% (17.6 lbs) at 6 mg, 9.3% (20.7 lbs) at 12 mg and 12.4% (27.3 lbs) at 36 mg, versus 0.9% on placebo ^[1]. At the highest dose, 59.6% of participants lost at least 10% of their body weight and 39.6% lost at least 15%, compared with 8.6% and 3.6% on placebo ^[1].

Lilly also reported a second way of measuring results, the treatment-regimen estimand, which counts everyone regardless of whether they stayed on the drug. By that measure the numbers are smaller: 11.2% (25.0 lbs) at 36 mg versus 2.1% (5.3 lbs) on placebo, with 54.6% losing at least 10% and 36.0% losing at least 15% ^[1]. Both analyses were statistically significant across the primary and all key secondary endpoints ^[1].

The company said the drug was linked to reductions in non-HDL cholesterol, triglycerides and systolic blood pressure in pooled analyses across doses ^[1]. In a pre-specified exploratory analysis, the 36 mg dose reduced high-sensitivity C-reactive protein, an inflammation marker, by 47.7% ^[1].

Side effects

The most common adverse events were gastrointestinal and generally mild to moderate ^[1]. Across the 6 mg, 12 mg and 36 mg doses, nausea occurred in 28.9%, 35.9% and 33.7% of participants versus 10.4% on placebo; constipation in 21.7%, 29.8% and 25.4% versus 9.3%; diarrhea in 21.0%, 22.8% and 23.1% versus 9.6%; vomiting in 13.0%, 21.4% and 24.0% versus 3.5%; and indigestion in 13.0%, 16.2% and 14.1% versus 5.0% ^[1].

Discontinuation because of side effects was 5.1% at 6 mg, 7.7% at 12 mg and 10.3% at 36 mg, versus 2.6% on placebo ^[1]. Overall dropout for any reason was actually higher in the placebo group at 29.9%, compared with 21.9% to 24.4% on orforglipron ^[1]. Lilly said no liver safety signal was seen ^[1].

Why it matters for patients

Orforglipron is a small-molecule pill, not a peptide, and Lilly says it can be taken at any time of day without restrictions on food or water ^[1]. That is a practical difference from currently available options for people who dislike injections or find them hard to manage. Doses in the trial were escalated in steps every four weeks, starting at 1 mg, which is how the company managed stomach side effects ^[1].

It is important to be clear about what this announcement is and is not. These are topline results from the drugmaker, not peer-reviewed data, and orforglipron is not approved by the FDA ^[1]. Lilly's own cautionary language notes there is no guarantee the drug will prove safe and effective or win approval ^[1]. ATTAIN-1 compared orforglipron only with placebo — it did not test it head-to-head against semaglutide or tirzepatide, so the sources do not support direct comparisons ^[1]. Pricing, insurance coverage and U.S. availability are not addressed in the announcement and are not yet known.

What happens next

Lilly said it plans to submit orforglipron to global regulators by the end of 2025 and is investing to meet expected demand at launch ^[1]. Detailed ATTAIN-1 results were slated for presentation at the European Association for the Study of Diabetes annual meeting in September 2025 and publication in a peer-reviewed journal ^[1]. More results from the ATTAIN program, which enrolled more than 4,500 people across two registration trials, and from the ACHIEVE program in type 2 diabetes were expected later in 2025 ^[1].