Foundayo Weight Loss Calculator
Estimate your possible weight loss on Foundayo (orforglipron) using the actual dose-by-dose results from Eli Lilly’s ATTAIN-1 trial — not a single “universal” percentage. Adjusts for your dose, your type 2 diabetes status, and shows how much of the result is likely the medication versus diet and exercise alone.
Reviewed for accuracy: January 2026 · Written and reviewed by Manzoor Ahmad, Pharmacist · Data sourced from the FDA-approved prescribing information and Eli Lilly’s ATTAIN-1 trial (NCT05869903)
These are the three maintenance doses studied in the trial — not a recommendation. Your prescriber determines your actual dose based on response and tolerability, starting at 0.8 mg and increasing gradually.
Trial results differ meaningfully by diabetes status — this toggle switches to the correct dataset.
Modeled trajectory shape (not week-by-week trial data) — calibrated to reach the official 72-week trial average. See methodology below.
Foundayo Weight Loss Results by Dose
Official 72-week average results from the ATTAIN-1 trial, published in Foundayo’s FDA-approved prescribing information. Percentages are of total body weight; pound figures are the trial’s own average starting weights, shown for reference — the calculator above applies these percentages to your own weight instead.
| Dose | Without T2D | With T2D |
|---|---|---|
| Placebo (diet + exercise only) | 2.1% | 2.5% |
| 5.5 mg | 7.4% | 5.1% |
| 9 mg | 8.3% | 7.0% |
| 17.2 mg (highest studied dose) | 11.1% | 9.6% |
How This Foundayo Weight Loss Calculator Works
This is not a generic “multiply by 11%” tool. Most Foundayo weight loss calculators online apply one universal percentage regardless of dose or diabetes status. This one uses the actual dose-specific, diabetes-status-specific averages Lilly reported in ATTAIN-1, and separates the placebo-arm result (people on diet and exercise alone still lost 2.1–2.5%) from the medication’s added effect.
The calculation
Projected loss = your weight × trial average % for your dose and diabetes status
Beyond-placebo loss = projected loss − (your weight × placebo-arm %). This is the portion of your result most plausibly attributable to the medication itself rather than the diet and exercise counseling every trial participant received.
Safety Information From the FDA Label
This section summarizes the FDA-approved prescribing information. It is not exhaustive — read the full label with your prescriber before starting Foundayo.
Boxed warning: thyroid C-cell tumors
GLP-1 receptor agonist medicines have caused thyroid C-cell tumors in rodent studies; the human relevance is undetermined. Notably, orforglipron (the drug in Foundayo) is not pharmacologically active in rats or mice and did not produce tumors in those studies — but Foundayo still carries the class boxed warning and is contraindicated for anyone with a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).
Pancreatitis
Acute pancreatitis has been reported. Seek care for persistent or severe abdominal pain, especially if it radiates to the back, with or without nausea and vomiting.
Gastrointestinal effects
Severe GI reactions occurred in about 3% of trial participants versus 1% on placebo. Foundayo isn’t recommended for people with severe gastroparesis.
Pregnancy & contraception
Discontinue if pregnancy is recognized. Anyone using oral contraceptives should switch to a non-oral method or add a barrier method for 30 days after starting and after each dose increase.
Limitations of This Calculator
Averages hide a wide range
An 11.1% average means many people lost more and many lost less — some participants in every GLP-1 trial lose very little weight. This projection is a starting expectation, not a promise.
Trial participants also changed diet and exercise
Every arm of ATTAIN-1, including placebo, received diet and lifestyle counseling. Foundayo is FDA-labeled for use alongside a reduced-calorie diet and increased physical activity — not as a substitute for either.
Not for cosmetic weight loss
Foundayo is indicated for chronic weight management in adults with obesity, or overweight adults with a weight-related condition — not for people simply wanting to lose a few pounds for appearance.
Requires an actual prescription
This tool cannot and does not prescribe Foundayo. Eligibility, dosing, and titration are determined by a licensed healthcare provider based on your full medical history.
Track the Full Picture
Weight loss on Foundayo is easiest to interpret alongside these related tools from our full health calculators library.
Frequently Asked Questions
In the 72-week ATTAIN-1 trial, adults without type 2 diabetes lost an average of 7.4% to 11.1% of body weight depending on dose, compared with 2.1% on placebo. Adults with type 2 diabetes lost somewhat less on average — 5.1% to 9.6%. Individual results vary widely around these averages.
Most people lose a modest amount in the first month — roughly 1 to 2% of body weight — since the first month is spent on the low 0.8 mg starting dose before increasing. The bulk of total weight loss tends to occur over the following several months as the dose is titrated up.
No. Foundayo (orforglipron) is a once-daily oral small-molecule GLP-1 receptor agonist, while Ozempic and Wegovy (semaglutide) and Zepbound and Mounjaro (tirzepatide) are injectable peptide medications. They work through related but not identical mechanisms, and trial results across the class aren’t directly comparable without controlling for study design.
Gastrointestinal effects — nausea, vomiting, diarrhea, and constipation — are the most commonly reported. Severe GI reactions occurred in about 3% of trial participants. See the Safety Information section above for the boxed warning and less common but more serious risks.
Foundayo is contraindicated for anyone with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2. It should be discontinued if pregnancy is recognized, and it isn’t recommended for people with severe gastroparesis or severe hepatic impairment. This is a summary, not the complete label — discuss your full history with a prescriber.
Yes. Foundayo is a prescription-only medication in the United States, FDA-approved for chronic weight management in adults with obesity, or overweight adults with at least one weight-related condition. A licensed healthcare provider determines eligibility and prescribes an appropriate dose.
References
- U.S. Food and Drug Administration. FOUNDAYO (orforglipron) Prescribing Information. AccessData.FDA.gov, 2026.
- National Library of Medicine. FOUNDAYO Label. DailyMed.NLM.NIH.gov.
- Eli Lilly and Company. What Is Foundayo (orforglipron). Foundayo.Lilly.com.
- ClinicalTrials.gov. ATTAIN-1: A Study of Orforglipron in Adults With Obesity or Overweight (NCT05869903).