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What Is Orforglipron? The Active Pharmaceutical Ingredient in the New GLP-1 Weight Loss Pill Fundayo Explained

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9 min

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Weight loss

Key Takeaways

  • Foundayo is a nonpeptide oral GLP-1 pill for weight loss,  manufactured exclusively by Eli Lilly, and which was FDA-approved on April 1, 2026

  • Unlike injectable GLP-1 medications, Foundayo can be taken any time of day without food or water restrictions

  • In the ATTAIN-1 clinical trial, participants on 12 mg of orforglipron (the active pharmaceutical ingredient in Foundayo) lost an average of 8.4% of their body weight over 72 weeks (the FDA-approved doses range up to 17.2 mg)

  • The most common side effects are gastrointestinal, including nausea, constipation, and diarrhea, and were mostly mild to moderate in clinical trials

  • At Mochi Health, independent licensed providers may prescribe FDA-approved Foundayo or a compounded medication containing orforglipron. 

Foundayo is a new FDA-approved oral weight loss medication manufactured by Eli Lilly (1, 3). The active pharmaceutical ingredient in Foundayo is orforglipron, a small molecule (non-peptide) GLP-1 receptor agonist. Foundayo was approved on April 1, 2026, for use in adults with obesity or overweight with at least one weight-related condition (1). Unlike injectable GLP-1 receptor agonists, Foundayo is a once-daily oral medication that you can take at any time of day, with or without food, and without any water restrictions (3). 

If you have been keeping up with the GLP-1 medications for weight loss, you will recognize how huge this is! In this article, we will cover: How Foundayo works, Results of the clinical trial, Side effects, How it compares to other GLP-1 receptor agonists, and Who may be eligible.

Key Takeaways

  • Foundayo is a nonpeptide oral GLP-1 pill for weight loss,  manufactured exclusively by Eli Lilly, and which was FDA-approved on April 1, 2026

  • Unlike injectable GLP-1 medications, Foundayo can be taken any time of day without food or water restrictions

  • In the ATTAIN-1 clinical trial, participants on 12 mg of orforglipron (the active pharmaceutical ingredient in Foundayo) lost an average of 8.4% of their body weight over 72 weeks (the FDA-approved doses range up to 17.2 mg)

  • The most common side effects are gastrointestinal, including nausea, constipation, and diarrhea, and were mostly mild to moderate in clinical trials

  • At Mochi Health, independent licensed providers may prescribe FDA-approved Foundayo or a compounded medication containing orforglipron. 

Foundayo is a new FDA-approved oral weight loss medication manufactured by Eli Lilly (1, 3). The active pharmaceutical ingredient in Foundayo is orforglipron, a small molecule (non-peptide) GLP-1 receptor agonist. Foundayo was approved on April 1, 2026, for use in adults with obesity or overweight with at least one weight-related condition (1). Unlike injectable GLP-1 receptor agonists, Foundayo is a once-daily oral medication that you can take at any time of day, with or without food, and without any water restrictions (3). 

If you have been keeping up with the GLP-1 medications for weight loss, you will recognize how huge this is! In this article, we will cover: How Foundayo works, Results of the clinical trial, Side effects, How it compares to other GLP-1 receptor agonists, and Who may be eligible.

What Is Foundayo and How Does It Work?

Foundayo is a new FDA-approved oral weight loss medication manufactured by Eli Lilly (1, 3). The active pharmaceutical ingredient in Foundayo is orforglipron, a small molecule (non-peptide) GLP-1 receptor agonist. Foundayo was approved on April 1, 2026, for use in adults with obesity or overweight with at least one weight-related condition (1). Unlike injectable GLP-1 receptor agonists, Foundayo is a once-daily oral medication that you can take at any time of day, with or without food, and without any water restrictions (3). 

GLP-1 (glucagon-like peptide-1) is a hormone involved in appetite and blood sugar regulation. Whenever you eat, your body releases a surge of GLP-1, which sends the “I’m full” signal to your brain. Foundayo works by activating the same receptors as your body’s naturally occurring GLP-1, leading to decreased hunger and food intake (1). 

Foundayo is indicated for use in adults with a BMI of 30 or higher (obesity), or a BMI of 27 or greater (overweight) with at least one weight-related condition, to be used in conjunction with a reduced-calorie diet and increased physical activity (1). Foundayo was approved by the FDA through the Commissioner’s National Priority Voucher pilot program, and was approved just 50 days after it was filed, making it the fastest new molecular entity approval since 2002 (1).

What Is Foundayo and How Does It Work?

Foundayo is a new FDA-approved oral weight loss medication manufactured by Eli Lilly (1, 3). The active pharmaceutical ingredient in Foundayo is orforglipron, a small molecule (non-peptide) GLP-1 receptor agonist. Foundayo was approved on April 1, 2026, for use in adults with obesity or overweight with at least one weight-related condition (1). Unlike injectable GLP-1 receptor agonists, Foundayo is a once-daily oral medication that you can take at any time of day, with or without food, and without any water restrictions (3). 

GLP-1 (glucagon-like peptide-1) is a hormone involved in appetite and blood sugar regulation. Whenever you eat, your body releases a surge of GLP-1, which sends the “I’m full” signal to your brain. Foundayo works by activating the same receptors as your body’s naturally occurring GLP-1, leading to decreased hunger and food intake (1). 

Foundayo is indicated for use in adults with a BMI of 30 or higher (obesity), or a BMI of 27 or greater (overweight) with at least one weight-related condition, to be used in conjunction with a reduced-calorie diet and increased physical activity (1). Foundayo was approved by the FDA through the Commissioner’s National Priority Voucher pilot program, and was approved just 50 days after it was filed, making it the fastest new molecular entity approval since 2002 (1).

What Did the ATTAIN-1 Clinical Trial Show?

The ATTAIN-1 clinical trial demonstrated that orforglipron resulted in significant weight loss at 72 weeks compared to a placebo (2). The ATTAIN-1 trial was a phase 3, randomized double-blind study published in the New England Journal of Medicine which enrolled 3,127 adults with obesity (without diabetes), and compared the efficacy of three different doses of orforglipron (6mg, 12mg, 36mg) with a placebo (2). It's worth noting that the FDA-approved doses of orforglipron range from 0.8 mg to 17.2 mg (1).

The ATTAIN-1 trial showed the following average body weight reductions over 72 weeks across all randomized participants (2):

  • 6 mg: 7.5% weight loss

  • 12 mg: 8.4% weight loss

  • 36 mg: 11.2% weight loss

  • Placebo: 2.1% weight loss


Figure 1. Weight loss results from the ATTAIN-1 trial by orforglipron dose (6 mg, 12 mg, and 36 mg) versus placebo over 72 weeks. Adapted from Wharton et al., NEJM 2025 (2).

Among participants who stayed on treatment for the full 72 weeks, the results were even more pronounced. The 12 mg group lost an average of 9.3% of their body weight, and the 6 mg group lost 7.8% (2). On the 12 mg dose, 63.5% of participants lost at least 5% of their body weight, and 40.0% lost at least 10% (2).

It wasn’t just the number on the scale that changed. The study also reported that people taking orforglipron had greater reductions in waist circumference, systolic blood pressure, triglycerides, and non-HDL cholesterol compared to those taking a placebo (2). 

In total, two randomized, double-blind, placebo-controlled trials were used to support the FDA’s approval of Foundayo (1).

What Did the ATTAIN-1 Clinical Trial Show?

The ATTAIN-1 clinical trial demonstrated that orforglipron resulted in significant weight loss at 72 weeks compared to a placebo (2). The ATTAIN-1 trial was a phase 3, randomized double-blind study published in the New England Journal of Medicine which enrolled 3,127 adults with obesity (without diabetes), and compared the efficacy of three different doses of orforglipron (6mg, 12mg, 36mg) with a placebo (2). It's worth noting that the FDA-approved doses of orforglipron range from 0.8 mg to 17.2 mg (1).

The ATTAIN-1 trial showed the following average body weight reductions over 72 weeks across all randomized participants (2):

  • 6 mg: 7.5% weight loss

  • 12 mg: 8.4% weight loss

  • 36 mg: 11.2% weight loss

  • Placebo: 2.1% weight loss


Figure 1. Weight loss results from the ATTAIN-1 trial by orforglipron dose (6 mg, 12 mg, and 36 mg) versus placebo over 72 weeks. Adapted from Wharton et al., NEJM 2025 (2).

Among participants who stayed on treatment for the full 72 weeks, the results were even more pronounced. The 12 mg group lost an average of 9.3% of their body weight, and the 6 mg group lost 7.8% (2). On the 12 mg dose, 63.5% of participants lost at least 5% of their body weight, and 40.0% lost at least 10% (2).

It wasn’t just the number on the scale that changed. The study also reported that people taking orforglipron had greater reductions in waist circumference, systolic blood pressure, triglycerides, and non-HDL cholesterol compared to those taking a placebo (2). 

In total, two randomized, double-blind, placebo-controlled trials were used to support the FDA’s approval of Foundayo (1).

What Are the Side Effects of Foundayo?

The majority of the side effects of Foundayo are gastrointestinal in nature, similar to other GLP-1 receptor agonists (1, 2). Common side effects listed by the FDA include (1):

  • Nausea

  • Constipation

  • Diarrhea

  • Vomiting

  • Indigestion (dyspepsia)

  • Stomach pain

  • Headache

  • Swollen belly (abdominal distension)

  • Fatigue

  • Belching

  • Heartburn (gastroesophageal reflux)

  • Gas

  • Hair loss

In the ATTAIN-1 trial, adverse events led to treatment discontinuation in 5.3% to 10.3% of people taking orforglipron, compared with 2.7% of people on placebo (2). The gastrointestinal side effects were mostly mild to moderate in severity (2). 

Foundayo also carries a boxed warning for thyroid C-cell tumors, including medullary thyroid carcinoma (1). It should not be used in anyone with a personal or family history of medullary thyroid cancer or Multiple Endocrine Neoplasia syndrome type 2 (1). Other serious warnings include pancreatitis, severe gastrointestinal reactions, acute kidney injury from volume depletion, low blood sugar (hypoglycemia), allergic reactions, gallbladder problems, diabetic retinopathy in people with type 2 diabetes, and pulmonary aspiration during general anesthesia or deep sedation (1).

If you notice side effects persisting or worsening, talk with your provider. Many GLP-1 side effects can be managed with dose adjustments and supportive care.

What Are the Side Effects of Foundayo?

The majority of the side effects of Foundayo are gastrointestinal in nature, similar to other GLP-1 receptor agonists (1, 2). Common side effects listed by the FDA include (1):

  • Nausea

  • Constipation

  • Diarrhea

  • Vomiting

  • Indigestion (dyspepsia)

  • Stomach pain

  • Headache

  • Swollen belly (abdominal distension)

  • Fatigue

  • Belching

  • Heartburn (gastroesophageal reflux)

  • Gas

  • Hair loss

In the ATTAIN-1 trial, adverse events led to treatment discontinuation in 5.3% to 10.3% of people taking orforglipron, compared with 2.7% of people on placebo (2). The gastrointestinal side effects were mostly mild to moderate in severity (2). 

Foundayo also carries a boxed warning for thyroid C-cell tumors, including medullary thyroid carcinoma (1). It should not be used in anyone with a personal or family history of medullary thyroid cancer or Multiple Endocrine Neoplasia syndrome type 2 (1). Other serious warnings include pancreatitis, severe gastrointestinal reactions, acute kidney injury from volume depletion, low blood sugar (hypoglycemia), allergic reactions, gallbladder problems, diabetic retinopathy in people with type 2 diabetes, and pulmonary aspiration during general anesthesia or deep sedation (1).

If you notice side effects persisting or worsening, talk with your provider. Many GLP-1 side effects can be managed with dose adjustments and supportive care.

How Is Foundayo Different From Other GLP-1 Medications?

Foundayo is different from other injectable GLP-1 medications in several key ways. The most obvious is that it’s an oral medication, a pill you take by mouth rather than an injection, which could be a big plus if you’ve avoided medication because you don’t like needles (3).

But it’s not just about how you take it. Foundayo is a small-molecule compound, not a peptide (2). Most current GLP-1 medications are peptides, and that’s a big reason they have to be injected. Foundayo is a nonpeptide compound that can survive digestion and is absorbed from a conventional tablet (2).

Convenience is also a factor. Convenience is a big part of what sets Foundayo apart from other oral GLP-1 weight loss options. Foundayo is the only oral GLP-1 for weight loss that doesn't have to be taken at a specific time of day, and that has no restrictions on eating and drinking (3). If you've taken other oral GLP-1 medications, you know that they usually come with instructions on timing, fasting, and hydration. This flexibility may make it easier to incorporate Foundayo into your routine.

The flip side: Foundayo is a once-daily medication, while GLP-1 injectables are usually injected once a week (3). So you'll trade the needle for a pill, but move from a weekly routine to a daily one.

Who Is Eligible for Foundayo?

Foundayo is approved by the FDA for use in adults with obesity (BMI 30 or above) or adults who are overweight (BMI 27 or above) with at least one weight-related condition (1). Foundayo should be used in combination with a lower-calorie diet and increased exercise. It is not intended to be used alone for weight loss (1). 

There are certain cases where you should not take Foundayo. According to the FDA and Eli Lilly, you should not take Foundayo if you (1, 3):

  • Have a personal or family history of medullary thyroid carcinoma

  • Have Multiple Endocrine Neoplasia syndrome type 2

  • Are currently taking another GLP-1 receptor agonist medication

Foundayo has not been studied in children (3). It may also interfere with oral contraceptives, so Eli Lilly recommends using an alternative form of birth control for 30 days after starting Foundayo and for 30 days after each dose increase (3).

FAQ's

When will Foundayo be available at pharmacies? 

Foundayo was FDA approved on April 1, 2026 (1). According to Eli Lilly, it began being available by prescription through LillyDirect immediately, and it will start shipping April 6, 2026 (3). It will also be available at retail pharmacies at a later date. You can speak with a licensed provider through Mochi Health’s telehealth platform to see if a prescription for Eli Lilly’s brand name Foundayo is right for you.

Can I take Foundayo with my other medications? 

You should not take Foundayo another GLP-1 receptor agonist (1). Foundayo may decrease the efficacy of oral contraceptives (3). Consult with your healthcare provider regarding all the medications you’re taking because some may need to be adjusted.

How much weight can I expect to lose on Foundayo? 

Results will vary from person to person. In the ATTAIN-1 trial, participants on 12 mg dose lost an average of 8.4% of their body weight over 72 weeks, compared with 2.1% for placebo (2). Results may also depend on the dose your provider prescribes, your starting weight, and how consistently you follow a reduced-calorie diet and increased physical activity alongside the medication.

Does Foundayo cause nausea? 

Nausea is the most common side effect of Foundayo as with other GLP-1 drugs (1, 2). In the ATTAIN-1 study, gastrointestinal side effects were generally mild or moderate (2). Starting at a low dose and gradually increasing, as the dosing schedule is designed to do, may help manage these effects.

Can providers prescribe compounded medications containing Orforglipron?

Yes. If appropriate and based on a licensed provider’s evaluation of a patient, a provider may prescribe a compounded medication containing orforglipron. To see whether FDA-approved Foundayo or a compounded medication containing orforglipron is right for you, speak with a licensed provider through Mochi Health’s telehealth platform.

Eli Lilly does not supply any of the ingredients used in compounded orforglipron. Compounded drugs, including compounded orforglipron, do not undergo review by FDA. FDA does not determine whether any compounded drug is safe or effective. 

FDA has acknowledged the necessity of compounded drugs in patient care. For more information about FDA’s stance on compounding in general, see Compounding and the FDA: Questions and Answers | FDA.

Check Your Eligibility

If you're interested in whether an oral GLP-1 medication like orforglipron could be a fit for your weight loss goals, a licensed provider on Mochi Health's telehealth platform can help you understand your options and determine the right path forward. Check your eligibility here.

Disclaimer: This article is for educational purposes only and should not be considered medical advice. The information provided does not constitute recommendations for treatment. Always consult with your healthcare provider about your specific situation, symptoms, and treatment options.


References

  1. U.S. Food and Drug Administration. (2026, April 1). FDA approves first new molecular entity under national priority voucher program [Press release]. https://www.fda.gov/news-events/press-announcements/fda-approves-first-new-molecular-entity-under-national-priority-voucher-program

  2. Wharton, S., Aronne, L. J., Stefanski, A., Alfaris, N. F., Ciudin, A., Yokote, K., Halpern, B., Shukla, A. P., Zhou, C., Macpherson, L., Allen, S. E., Ahmad, N. N., & Klise, S. R. (2025). Orforglipron, an oral small-molecule GLP-1 receptor agonist for obesity treatment. New England Journal of Medicine, 393(18), 1796-1806. https://doi.org/10.1056/NEJMoa2511774

  3. Eli Lilly and Company. (2026, April 1). FDA approves Lilly's Foundayo (orforglipron), the only GLP-1 pill for weight loss that can be taken any time of day without food or water restrictions [Press release]. https://investor.lilly.com/news-releases/news-release-details/fda-approves-lillys-foundayotm-orforglipron-only-glp-1-pill

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All professional medical services are provided by licensed physicians and clinicians affiliated with independently owned and operated professional practices. Mochi Health Corp. provides administrative and technology services to affiliated medical practices it supports, and does not provide any professional medical services itself.

Personalized care for long-term wellness

Small wins add up to big transformations. Mochi reminds us to focus on what’s good and use it to build the life we envision.

All professional medical services are provided by licensed physicians and clinicians affiliated with independently owned and operated professional practices. Mochi Health Corp. provides administrative and technology services to affiliated medical practices it supports, and does not provide any professional medical services itself.

Personalized care for long-term wellness

Small wins add up to big transformations. Mochi reminds us to focus on what’s good and use it to build the life we envision.

All professional medical services are provided by licensed physicians and clinicians affiliated with independently owned and operated professional practices. Mochi Health Corp. provides administrative and technology services to affiliated medical practices it supports, and does not provide any professional medical services itself.

Personalized care for long-term wellness

Small wins add up to big transformations. Mochi reminds us to focus on what’s good and use it to build the life we envision.

All professional medical services are provided by licensed physicians and clinicians affiliated with independently owned and operated professional practices. Mochi Health Corp. provides administrative and technology services to affiliated medical practices it supports, and does not provide any professional medical services itself.

Personalized care for long-term wellness

Small wins add up to big transformations. Mochi reminds us to focus on what’s good and use it to build the life we envision.

All professional medical services are provided by licensed physicians and clinicians affiliated with independently owned and operated professional practices. Mochi Health Corp. provides administrative and technology services to affiliated medical practices it supports, and does not provide any professional medical services itself.