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Foundayo vs Xenical

Last reviewed: September 2026Based on 2 clinical trials

Foundayo (orforglipron, daily pill) and Xenical (orlistat, capsule, three times daily with meals) are both approved for weight loss in the United States. No head-to-head trial has compared these two drugs. The figures below come from separate trials, each with its own participants, length and comparison group.

At a glance

Foundayo and Xenical compared on form, trial results, cost and reported side effects
AttributeFoundayoXenical
FormDaily pill3x daily with meals
How oftenOnce-daily pill — no injection, no fasting, no food timingThree capsules daily, taken with each fat-containing meal
Weight loss in trialsUp to 12.4% — ATTAIN-1 (72 weeks)Up to 8.5% — Sjostrom 1-year RCT (52 weeks)
FDA approved20261999
Made byEli LillyRoche (Xenical) / GSK (Alli OTC)
How it worksA small-molecule (non-peptide) GLP-1 receptor agonist.Blocks pancreatic lipase enzymes in the small intestine, preventing approximately 30% of dietary fat from being broken down and absorbed.
Monthly cost, self-pay$149–$349/mo$40–$400/moover-the-counter strength; prescription runs to $400
Most reported reactionNausea 33% (ATTAIN-1)Oily/fatty stools (steatorrhoea) 27% (XENDOS)
Every figure in this table is read from the same trial and label records used everywhere else on this site.

Weight loss in each drug's main trial

No head-to-head trial has compared these two drugs.

Foundayo(orforglipron)12.4%

ATTAIN-1 (72 weeks)

Xenical(orlistat)8.5%

Sjostrom 1-year RCT (52 weeks)

In clinical trials, participants taking orforglipron lost on average up to 12.4% of their starting body weight, and participants taking orlistat lost on average up to 8.5%. Those numbers come from two different studies: ATTAIN-1 enrolled 3,127 adults with obesity or overweight with comorbidities, no type 2 diabetes over 72 weeks against placebo, while Sjostrom 1-year RCT enrolled 743 adults with obesity over 1 year (52 weeks) against placebo. Who took part, how long each trial ran and what each drug was measured against all move the percentage, so the two figures are not a measured difference between the drugs.

Monthly cost, self-pay

The bar spans the range in each drug's price record — lowest listed price to highest.

Foundayo$149–$349/mo

$149/month self-pay at the lowest dose, up to $349/month at the highest dose via LillyDirect. $25/month with the commercial insurance savings card. Medicare Part D coverage expected from July 2026 at ~$50/month.

Xenical$40–$400/mo

over-the-counter strength; prescription runs to $400

Prescription Xenical ~$200–$400/month; over-the-counter Alli (60mg) ~$40–$60/month.

Self-pay prices are what the manufacturer or the pharmacy lists, not what most people end up paying. Foundayo: $149–$349/month. Xenical: $40–$400/month. Insurance, dose and pharmacy all change both figures.

Side effects reported in the trials

ATTAIN-1 and XENDOS did not report the same reactions, so there is no shared row to line up. Each drug's own reported rates are listed below.

Foundayo
  • Nausea33%
  • Vomiting19%
  • Constipation18%
  • Diarrhoea15%

From ATTAIN-1

Xenical
  • Oily/fatty stools (steatorrhoea)27%
  • Faecal urgency22%
  • Oily spotting on underwear27%
  • Faecal incontinence8%
  • Abdominal pain/discomfort14%

From XENDOS

A rate is the share of trial participants who reported that reaction, not a prediction for any one person.

How they differ in practice

How you take it

  • Foundayo — Once-daily oral tablet. No food or water restrictions.
  • Xenical — Oral capsule 120 mg, three times daily with meals (prescription). Also available OTC as Alli at 60 mg.

Dose build-up

  • Foundayo — 0.8 mg → 2.5 mg → 5.5 mg, then optionally 9, 14.5 or 17.2 mg; at least 30 days on each dose

Where a drug is not listed here, its prescribing information sets out its own dose steps.

How soon it acts

  • Foundayo — Appetite changes typically within the first 4 weeks; meaningful weight loss by 12–16 weeks
  • Xenical — Weight effects begin from the first week (related to calorie malabsorption), but significant loss takes 8–12 weeks

Heart and metabolic findings

  • Foundayo — Cardiovascular outcomes data pending.
  • Xenical — In the 4-year XENDOS trial, orlistat reduced progression from prediabetes to type 2 diabetes by 37% compared to placebo plus lifestyle changes.

As stated in each drug’s trial record — not a claim about which drug protects the heart more.

Other findings recorded

  • Foundayo — No food or water restrictions — take any time of day; available at $149/month self-pay (lowest dose) or $25/month with commercial insurance
  • Xenical — 37% reduction in progression to type 2 diabetes (XENDOS, 4 years); only approved obesity drug with a 4-year safety dataset

If you stop taking it

  • Foundayo — No withdrawal trial has been published for Foundayo.
  • Xenical — Weight is typically regained after stopping.

Common questions

Written and maintained by one person · Built with agentic AI tools · Every number checked against the cited trial · Not medical advice

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Compare all optionsEvery approved drug side by side, plus the other head-to-head pagesFoundayo in fullFoundayo — results, side effects, cost and how it is takenXenical in fullXenical & Alli — results, side effects, cost and how it is takenTake the option finder quizAnswer a few questions and see which options fit your situation

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Medical disclaimer: This website is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any treatment. Prices shown are United States self-pay or list prices and vary by insurance and country.