ATTAIN-1 topline: 27.3 pounds lost on the highest dose

Eli Lilly reported topline results from ATTAIN-1, the first of two pivotal Phase 3 obesity trials of orforglipron, an oral GLP-1 receptor agonist taken once daily as a tablet. Adults on the highest dose who stayed on treatment lost an average of 27.3 pounds, or 12.4% of body weight, over 72 weeks ^[1].

ATTAIN-1 was a 72-week, randomized, double-blind, placebo-controlled trial in 3,127 adults with obesity, or overweight with a weight-related health problem, who did not have diabetes ^[1]. Participants on the highest dose tested, 36 mg, lost an average of 27.3 pounds (12.4%) compared with 2.2 pounds (0.9%) on placebo, using the analysis that counts people who remained on treatment ^[1].

A second way of measuring the same trial counts everyone who was randomized, whether or not they finished the study or stayed on the drug. By that measure, people taking orforglipron lost an average of 25 pounds (11.1%) compared with 5.3 pounds (2.1%) on placebo ^[1]. The gap between the two sets of numbers reflects dropouts and people who stopped the medication, and it is a standard reason trial results can be quoted two different ways.

Beyond the scale, Lilly said treatment was linked to reductions in several cardiometabolic risk markers, including waist circumference, non-HDL cholesterol, triglycerides and systolic blood pressure ^[1]. The source does not give the size of those changes.

What the topline did not say

The summary available here does not include ATTAIN-1's discontinuation rates, the share of participants who reached specific weight-loss thresholds, or the rates of nausea, vomiting and other gastrointestinal side effects at each dose. Those details are not yet known from this source. For context, in the companion trial ATTAIN-2, in adults with obesity or overweight and type 2 diabetes, Lilly said the overall safety profile was consistent with the established GLP-1 receptor agonist class, and participants on the highest dose lost an average of 22.9 pounds (10.5%) at 72 weeks ^[1].

One wrinkle worth flagging: the trial doses were 6 mg, 12 mg and 36 mg ^[1], while the tablet strengths later approved in the United States run from 0.8 mg to a maximum of 17.2 mg once daily ^[1]. The source does not explain why the numbers differ.

Why it matters for patients

Orforglipron is a small-molecule, non-peptide GLP-1 drug, which means it can be made as a pill rather than an injection ^[1]. For people who dislike needles, or who have had trouble getting injectable semaglutide (Ozempic, Wegovy) or tirzepatide (Mounjaro, Zepbound), an oral option that does not require food or water restrictions changes the practical picture of what treatment looks like day to day ^[1].

The trade-off visible in these numbers is size of effect. A 12.4% average reduction at 72 weeks on the top dose is meaningful but sits below what the injectable incretin drugs have reported in their own pivotal trials. Because ATTAIN-1 did not compare orforglipron head-to-head against Wegovy or Zepbound, no direct comparison can be drawn from this trial ^[1].

The drug's label, issued later, carries a boxed warning for the risk of thyroid C-cell tumors, plus warnings covering acute pancreatitis, severe gastrointestinal reactions, acute kidney injury from volume depletion, low blood sugar, serious allergic reactions, diabetic retinopathy complications in people with type 2 diabetes, gallbladder disease, and pulmonary aspiration during anesthesia ^[1]. Common side effects reported in at least 5% of patients include nausea, constipation, diarrhea, vomiting, indigestion, abdominal pain, headache, bloating, fatigue, burping, reflux, gas and hair loss ^[1].

What happens next

Complete ATTAIN-1 results were published in the New England Journal of Medicine on September 16, 2025 ^[1]. On August 26, 2025, Lilly said a third Phase 3 trial succeeded, triggering global regulatory submissions for obesity that year ^[1]. The FDA approved the drug as Foundayo on April 1, 2026, for adults with obesity or overweight with at least one weight-related condition, alongside a reduced-calorie diet and more physical activity ^[1]. Pricing and insurance coverage are not addressed in this source.