Foundayo Results: What the Clinical Trials Actually Show

In the main obesity trial, ATTAIN-1, people taking the highest dose of Foundayo (orforglipron) lost an average of 12.4% of their body weight over 72 weeks by the efficacy estimand — about 27.3 lbs (12.4 kg) from an average starting weight of 103.2 kg (227.5 lbs) — compared with 0.9% (2.2 lbs) for people taking placebo, also by the efficacy estimand ^[1]. The trial randomized 3,127 adults with obesity, or overweight with a weight-related condition and no diabetes. The results were presented at the EASD 2025 meeting and published in The New England Journal of Medicine; Lilly announced them in a release dated September 16, 2025 ^[1]. Foundayo is now an FDA-approved tablet in the U.S.; the trials themselves used an investigational capsule formulation at doses later shown to match the approved tablets ^[3][6][8][9].

The reason different sources quote different numbers — 12.4% versus 11.2%, for example — is not disagreement about the data. It is that the same trial results were calculated two ways, using two statistical methods called estimands, and headlines often pick one without saying which ^[1]. The numbers below name the estimand each time, because the two methods answer different questions.

Why do some sources say 12.4% and others say 11.2%?

Both numbers describe the same group of people on the highest dose at week 72 of ATTAIN-1. They differ in what question each one answers ^[1].

The efficacy estimand represents efficacy had all randomized participants remained on the study intervention — with possible dose interruptions and modifications — for 72 weeks without initiating prohibited weight-management treatments ^[1]. By that measure, the highest dose produced -12.4% (-12.4 kg; -27.3 lbs) and placebo produced -0.9% (-1.0 kg; -2.2 lbs) ^[1].

The treatment-regimen estimand represents the estimated average treatment effect regardless of adherence to the study intervention or initiation of prohibited weight-management treatments ^[1][4]. By that measure, the highest dose produced -11.2% (-11.3 kg; -25.0 lbs) and placebo produced -2.1% (-2.4 kg; -5.3 lbs) ^[1].

So a headline quoting 12.4% is using the efficacy estimand, and one quoting 11.2% is using the treatment-regimen estimand. Neither is wrong; they are answers to different questions, and a report that does not say which is being used is leaving out the key fact ^[1].

How much weight did people lose at each dose?

ATTAIN-1 tested three dose levels. In the trial’s capsule formulation these were 6 mg, 12 mg and 36 mg, which correspond to the approved tablet doses of 5.5 mg, 9 mg and 17.2 mg ^[1][6][8][9]. Here are the week-72 weight changes from an average baseline of 103.2 kg (227.5 lbs) and a BMI of 37.0 ^[1]:

Dose (tablet equivalent)	Efficacy estimand	Treatment-regimen estimand
5.5 mg	-7.8% (-8.0 kg; -17.6 lbs)	-7.5% (-7.8 kg; -17.2 lbs)
9 mg	-9.3% (-9.4 kg; -20.7 lbs)	-8.4% (-8.6 kg; -19.0 lbs)
17.2 mg	-12.4% (-12.4 kg; -27.3 lbs)	-11.2% (-11.3 kg; -25.0 lbs)
Placebo	-0.9% (-1.0 kg; -2.2 lbs)	-2.1% (-2.4 kg; -5.3 lbs)

All figures are from the Lilly results release for ATTAIN-1 ^[1]. The dose-response pattern is consistent: higher doses produced more average weight loss under both estimands.

What share of people lost 5%, 10%, 15% or 20% of their weight?

Averages hide the spread. ATTAIN-1 also reported how many people reached specific weight-loss milestones at week 72 ^[1].

Under the efficacy estimand ^[1]:

Milestone	5.5 mg	9 mg	17.2 mg	Placebo
At least 5% loss	63.8%	69.3%	77.1%	22.1%
At least 10% loss	35.9%	45.1%	59.6%	8.6%
At least 15% loss	16.5%	24.0%	39.6%	3.6%
At least 20% loss	7.2%	11.4%	20.1%	1.6%

Under the treatment-regimen estimand, the top-dose figures were 71.8% for at least 5%, 54.6% for at least 10%, 36.0% for at least 15% and 18.4% for at least 20%, versus placebo rates of 26.8%, 12.9%, 5.9% and 2.8% ^[1]. One footnote from the release applies here: the percentage of participants achieving body weight reductions of ≥20% with the 6 mg dose was not controlled for family-wise type 1 error rate ^[1].

Put plainly, on the highest dose roughly 6 in 10 people lost at least 10% of their body weight and about 4 in 10 lost at least 15%, by the efficacy estimand ^[1]. These are group averages from a trial population, not a prediction for any one person.

Did anything besides weight change?

Yes. ATTAIN-1 reported several cardiometabolic measures at week 72, and the highest dose improved them relative to placebo under the efficacy estimand ^[1]:

• Waist circumference: -11.1 cm (-4.4 in) versus -2.1 cm (-0.8 in) with placebo, from an average baseline of 112.4 cm (44.25 in) ^[1].
• Systolic blood pressure: -6.7 mm Hg versus -0.8 mm Hg, from a baseline of 125.5 mm Hg ^[1].
• Triglycerides: -21.6% versus -4.8%, from a baseline of 138.8 mg/dL ^[1].
• Non-HDL cholesterol: -8.5% versus -1.4%, from a baseline of 146.4 mg/dL ^[1].
• hsCRP (a marker of inflammation): reduced 47.7% at the highest dose in a pre-specified exploratory analysis ^[1].

Among the 1,127 participants who had prediabetes at the start of the study, up to 91% of those taking orforglipron reached near-normal blood sugar levels by week 72, compared with 42% of those on placebo ^[1]. That is a trial observation, not a claim that the drug prevents type 2 diabetes.

Who was in ATTAIN-1, and how was the trial run?

ATTAIN-1 (NCT05869903) was a Phase 3, 72-week, randomized, double-blind, placebo-controlled trial that randomized 3,127 participants in a 3:3:3:4 ratio to the three orforglipron doses or placebo ^[1][9]. Sites were located in the U.S., Brazil, China, India, Japan, South Korea, Puerto Rico, Slovakia, Spain and Taiwan ^[1][9].

To enter, participants needed a BMI of 30 or higher, or 27 or higher with at least one of hypertension, dyslipidemia, obstructive sleep apnea or cardiovascular disease, plus at least one self-reported failed dietary effort to lose weight; people with diabetes were excluded ^[1][9].

One design detail affects how the results compare with other obesity trials: ATTAIN-1 was the first Phase 3 study in this population in which treatment was evaluated as an adjunct to exercise and a balanced, healthy diet rather than a reduced-calorie diet ^[1][9]. The approved product label, by contrast, states the indication is in combination with a reduced-calorie diet and increased physical activity ^[3].

Everyone in the orforglipron arms started at 1 mg once daily and stepped up every four weeks to their assigned maintenance dose; dose reduction was allowed only for gastrointestinal tolerability if other mitigations failed ^[1].

What about side effects and dropouts?

The most common adverse events in ATTAIN-1 were gastrointestinal and generally mild to moderate ^[1]. Rates by dose (6 mg, 12 mg, 36 mg capsule) versus placebo ^[1]:

Adverse event	6 mg	12 mg	36 mg	Placebo
Nausea	28.9%	35.9%	33.7%	10.4%
Constipation	21.7%	29.8%	25.4%	9.3%
Diarrhea	21.0%	22.8%	23.1%	9.6%
Vomiting	13.0%	21.4%	24.0%	3.5%

Discontinuation due to adverse events was 5.3% on the lowest dose, 7.9% on the middle dose and 10.3% on the highest dose, versus 2.7% on placebo ^[1]. No hepatic safety signal was observed in ATTAIN-1 or in ATTAIN-2 ^[1][4].

What were the results in people who also have type 2 diabetes?

A separate trial, ATTAIN-2 (NCT05872620), tested the same three doses in adults with a BMI of 27 or higher who also had type 2 diabetes. It randomized more than 1,600 participants over 72 weeks in a 1:1:1:2 ratio ^[4]. Average baseline weight was 101.4 kg (223.5 lbs) and average baseline A1C was 8.1% ^[4].

At the highest dose, participants lost an average of 10.5% of body weight (-10.4 kg; -22.9 lbs) at 72 weeks by the efficacy estimand, versus 2.2% (-2.3 kg; -5.1 lbs) on placebo ^[4]. By the treatment-regimen estimand, the top-dose figure was -9.6% (-21.2 lbs) versus -2.5% (-6.0 lbs) on placebo ^[4].

Milestone results at the highest dose, efficacy estimand: 50.1% lost at least 10% of body weight (versus 7.0% on placebo) and 28.4% lost at least 15% (versus 1.9%) ^[4].

Blood sugar also improved. By the efficacy estimand, A1C fell 1.3% to 1.8% across the three doses versus 0.1% on placebo; 75.0% of people on the highest dose reached A1C ≤6.5% versus 10.6% on placebo, and 85.1% reached A1C under 7% versus 23.0%, all by the efficacy estimand ^[4]. In a pre-specified exploratory analysis, the highest dose reduced hsCRP by 50.6% ^[4]. Discontinuation due to adverse events was 6.1%, 10.6% and 10.6% across doses versus 4.6% on placebo ^[4].

Separately, Lilly reported an indirect treatment comparison on September 29, 2026, in which adults with type 2 diabetes taking Foundayo 17.2 mg lost 1.5% more of their body weight over 52 weeks than those taking oral semaglutide 25 mg (95% CI -2.7%, -0.2%), and lowered A1C by 0.3% more (95% CI -0.6%, -0.1%) ^[16]. Across different statistical methods, the differences ranged from 1.5% to 2.4% for weight loss and 0.3% to 0.6% for A1C reduction, in an analysis covariate-adjusted for gender, age, baseline A1C and baseline weight ^[16]. ACHIEVE-3 (NCT06045221) is a Phase 3, 52-week, randomized, open-label trial evaluating orforglipron compared with oral semaglutide (Rybelsus) in adults with type 2 diabetes inadequately controlled with metformin ^[16].

The U.S. product label covers weight management only; the label text does not include a type 2 diabetes indication ^[3].

Does it work as well after age 65?

A post hoc subgroup analysis pooled adults 65 and older from ATTAIN-1 and ATTAIN-2: 616 randomized participants, of whom 613 received treatment (5.5 mg, n=118; 9 mg, n=135; 17.2 mg, n=146; placebo, n=214) ^[8].

At week 72 in ATTAIN-1, weight change was -7.9%, -11.3% and -13.0% across the three doses versus -1.6% on placebo, all p<0.001 ^[8]. In ATTAIN-2, the figures were -7.5%, -8.3% and -12.2% versus -2.3% on placebo, all p<0.001 ^[8]. Findings were comparable in participants under 65, and gastrointestinal adverse events were the most common and generally mild to moderate ^[8].

Two cautions: this was a post hoc analysis, not a pre-specified trial endpoint, and it is a subgroup, so the numbers are less certain than the main trial results ^[8].

Does menopause stage change the results?

Post hoc analyses of more than 1,500 women in ATTAIN-1 and ATTAIN-2, presented at the ADA 86th Scientific Sessions in a Lilly release dated June 7, 2026, broke results down by menopausal stage at the highest dose (17.2 mg) ^[9].

In ATTAIN-1 at 72 weeks: pre-menopause -12.8% (-28.0 lbs, n=171); perimenopause -14.4% (-30.4 lbs, n=142); post-menopause -14.1% (-28.2 lbs, n=152) ^[9]. In ATTAIN-2: pre-menopause -11.3% (-23.4 lbs, n=10); perimenopause -8.9% (-18.5 lbs, n=33); post-menopause -13.6% (-27.8 lbs, n=109) ^[9].

Up to 51.5% of women in ATTAIN-1 and up to 44.2% in ATTAIN-2 lost at least 15% of body weight, and waist circumference fell by up to 4.9 in (12.5 cm) in ATTAIN-1 and up to 4.3 in (11.0 cm) in ATTAIN-2 ^[9]. The ATTAIN-2 pre-menopause subgroup was very small (n=10), so that particular figure should not be read as precise ^[9]. Like the age-65 analysis, these are post hoc subgroup analyses rather than pre-specified endpoints ^[8][9].

What happens when people switch from an injectable to the pill?

ATTAIN-MAINTAIN (NCT06584916) was a Phase 3b, double-blind, placebo-controlled trial that screened 400 people, enrolled 376 at 29 U.S. sites between September 13, 2024 and November 21, 2025, and enrolled people who had completed 72 weeks of tirzepatide (cohort 1, N=205) or semaglutide (cohort 2, N=171) in the SURMOUNT-5 study ^[6].

Cohort 1 was randomized 125 to orforglipron (36 mg capsule-equivalent or maximum tolerated dose) versus 80 to placebo; cohort 2 was 105 versus 66 ^[6]. At week 52, cohort 1 participants who achieved a body weight plateau maintained a model-based estimate of 74.7% of their prior weight reduction on orforglipron versus 49.2% on placebo — a treatment difference of 25.5% (95% CI 14.5 to 36.5), P<0.001, treatment-regimen estimand ^[6]. Cohort 2 participants who achieved a body weight plateau maintained a model-based estimate of 79.3% versus 37.6%, a difference of 41.7 (95% CI 24.4 to 59.0), P<0.001, also by the treatment-regimen estimand ^[6].

All key secondary endpoints were met, and the most common adverse events were gastrointestinal, mostly mild to moderate ^[6]. The trial’s stated limitations: there was no arm that continued the injectable, and follow-up lasted only one year ^[6]. In other words, this trial compared switching to the pill versus taking placebo, not versus staying on the injectable ^[6].

What does “36 mg orforglipron” mean versus the 17.2 mg tablet?

The Phase 3 trials used investigational capsules at 1, 3, 6, 12, 24 and 36 mg ^[6]. Those capsule doses have been shown equivalent or bioequivalent to tablet doses of 0.8, 2.5, 5.5, 9, 14.5 and 17.2 mg, which are the strengths approved in the U.S. ^[6][8]. So when 2025 coverage referred to “36 mg orforglipron,” that is the same amount of drug as the 17.2 mg Foundayo tablet ^[6][8]. Headlines using capsule numbers and tablet numbers are describing the same doses.

How is the approved product labeled and dosed?

FOUNDAYO (orforglipron) tablets received initial U.S. approval in 2026, with the label revised in July 2026 ^[3]. The label states the indication: in combination with a reduced-calorie diet and increased physical activity, to reduce excess body weight and maintain that reduction long term in adults with obesity, or adults with overweight plus at least one weight-related comorbid condition ^[3].

Tablet strengths are 0.8, 2.5, 5.5, 9, 14.5 and 17.2 mg ^[3]. The labeled dosing schedule starts at 0.8 mg once daily, with increases allowed after at least 30 days at each step, up to a maximum of 17.2 mg once daily ^[3]. That is label information about how the product is prescribed, not a recommendation for any individual.

The label carries a boxed warning about the risk of thyroid C-cell tumors, and the drug is contraindicated in people with a personal or family history of medullary thyroid carcinoma or MEN 2 ^[3]. The most common adverse reactions reported in 5% or more of patients are nausea, constipation, diarrhea, vomiting, dyspepsia, abdominal pain, headache, abdominal distension, fatigue, eructation, gastroesophageal reflux disease, flatulence and hair loss ^[3]. The maximum dose is 9 mg once daily when used with a strong CYP3A4 inhibitor, and concomitant use with another GLP-1 receptor agonist is not recommended ^[3].

What questions do the published results not answer yet?

Several things people ask about are not answered by the results published so far:

• ATTAIN-MAINTAIN compared switching to orforglipron against placebo, not against staying on the injectable ^[6]. Any comparison of Foundayo trial numbers with figures from other drugs’ trials is not a head-to-head measurement ^[1][6].
• The obesity data run to 72 weeks, and ATTAIN-MAINTAIN to 52 weeks ^[1][6].
• The age-65 and menopause findings are post hoc subgroup analyses, not pre-specified endpoints ^[8][9].
• At the time of the June 2026 release, Lilly listed ongoing studies in type 2 diabetes, obstructive sleep apnea, osteoarthritis knee pain, hypertension, peripheral artery disease and stress urinary incontinence ^[9].

Finally, the trial averages above describe groups of participants under specific statistical assumptions. They are not a forecast of what any individual will lose, and decisions about starting, dosing or switching medications belong with a clinician.

Sources

1. Eli Lilly and Company. Lilly’s oral GLP-1, orforglipron, demonstrated meaningful weight loss and cardiometabolic improvements in complete ATTAIN-1 results published in The New England Journal of Medicine. September 16, 2025.
2. ClinicalTrials.gov. A Study of Orforglipron (LY3502970) in Adult Participants With Obesity or Overweight With Weight-Related Comorbidities.
3. Eli Lilly and Company. FOUNDAYO (orforglipron) tablets, for oral use. Initial U.S. Approval: 2026.
4. Eli Lilly and Company. Lilly’s oral GLP-1, orforglipron, is successful in third Phase 3 trial, triggering global regulatory submissions this year for the treatment of obesity. August 26, 2025.
5. The Lancet. Efficacy and safety of once-daily oral orforglipron compared with oral semaglutide in adults with type 2 diabetes (ACHIEVE-3): a multinational, multicentre, non-inferiority, open-label, randomised, phase 3 trial.
6. Nature Medicine. Orforglipron for maintenance of body weight reduction: the double-blind, randomized phase 3b ATTAIN-MAINTAIN trial.
7. Reddit. Online discussion thread about the Foundayo pill.
8. PubMed. Orforglipron for obesity treatment in older patients ≥65 years with or without type 2 diabetes: A post hoc subgroup analysis of the ATTAIN-1 and ATTAIN-2 trials.
9. Eli Lilly and Company. Lilly’s Foundayo (orforglipron), the only oral GLP-1 taken without food or water restrictions, was associated with significant weight loss in women at every stage of menopause. June 7, 2026.
10. Eli Lilly and Company. ACHIEVE-4, the longest Phase 3 study of Lilly’s Foundayo (orforglipron) to date, reaffirmed its cardiovascular and overall safety profile. April 16, 2026.
11. ClinicalTrials.gov. A Study of Orforglipron (LY3502970) on Cardiovascular Outcomes in Adults With Atherosclerotic Cardiovascular Disease and/or Chronic Kidney Disease (ATTAIN-Outcomes).
12. PubMed. Orforglipron, an Oral Small-Molecule GLP-1 Receptor Agonist for Obesity Treatment.
13. Drugs.com. Foundayo User Reviews & Ratings.
14. PR Newswire. Lilly reports second-quarter 2026 financial results, raises full-year guidance, and highlights continued growth and pipeline progress.
15. US Food and Drug Administration. FOUNDAYO (orforglipron) tablets, for oral use. Initial U.S. Approval: 2026.
16. BioSpace. Lilly’s Foundayo (orforglipron) 17.2 mg showed greater weight loss and A1C reduction than oral semaglutide 25 mg among adults with type 2 diabetes in a new indirect treatment comparison. biospace.com.