Foundayo does one thing: it activates the GLP-1 receptor. Retatrutide does three: GLP-1, GIP, and glucagon.
That gap explains most of the difference in results.
Data comparison
Drug Delivery Receptors Headline weight loss
Foundayo Daily oral GLP-1 11.2% at 72 weeks
Retatrutide Weekly injection GLP-1 + GIP + glucagon 24.2% at 48 weeks
GLP-1 activity alone reliably produces weight loss in the low-to-mid teens. Adding GIP (tirzepatide) pushes it to around 20%. Adding the glucagon arm on top, which in animal studies raises energy expenditure rather than just cutting intake, is how retatrutide is aiming for the high 20s.
A caveat almost every “Foundayo vs” article drops
None of these drugs has been tested head-to-head against Foundayo for weight loss. Every number in that table comes from a separate trial with its own population, length, and placebo group.
The one direct comparison that exists is in type 2 diabetes: in ACHIEVE-3, orforglipron beat oral semaglutide at the lower 7 and 14 mg diabetes doses on both blood sugar and weight.
Conclusion
On published numbers, Retatrutide’s weight loss is far better than Foundayo’s. But Foundayo’s selling points are convenience, price, and a legal prescription, not the biggest result.