Two new weight loss medications from Eli Lilly offer women different options for managing their weight, but they're not equally effective. Foundayo, a daily oral tablet containing orforglipron, and Zepbound, a weekly injection containing tirzepatide, both work as glucagon-like peptide-1 (GLP-1) medications that reduce appetite and help people feel fuller longer. However, clinical trial data shows a meaningful difference in how much weight women can expect to lose with each option .

How Much Weight Loss Can Women Expect From Each Drug?

The weight loss results between these two medications differ substantially. In a 72-week clinical trial, women taking Zepbound lost approximately 15% to 22% of their starting body weight, depending on their dose. By contrast, women in a 72-week Foundayo trial lost 7.5% to 11.2% of their starting weight at the maximum studied dose. For a woman weighing 200 pounds, this means Zepbound could result in 30 to 44 pounds of weight loss, while Foundayo might deliver 15 to 22 pounds .

The difference in effectiveness comes down to how these drugs work at the molecular level. Foundayo is a single GLP-1 receptor agonist, meaning it mimics one gut hormone. Zepbound is a GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) dual receptor agonist, meaning it targets two hormones simultaneously. This dual action allows Zepbound to regulate metabolism more comprehensively by affecting the brain and fat tissue in ways Foundayo cannot .

What Are the Key Differences in How Women Take These Medications?

The most obvious difference is convenience and frequency. Foundayo requires daily commitment; women take one tablet by mouth at the same time each day, with or without food. Zepbound requires only a weekly self-administered injection under the skin, rotating injection sites between the abdomen, thigh, and upper arm. For women with busy schedules or needle anxiety, this distinction matters significantly .

Another critical difference is bioavailability, which refers to how much of the active ingredient actually reaches the bloodstream. Foundayo has a bioavailability of only 20% to 40% because the gastrointestinal tract absorbs oral GLP-1s less efficiently than injected medications. Zepbound achieves approximately 80% bioavailability, meaning far more of the drug reaches the bloodstream to do its job. This explains why Zepbound delivers superior weight loss results despite being from the same manufacturer .

How Do Dosing Schedules Compare for Women Starting These Medications?

Both medications use a gradual dose escalation approach, starting low and increasing every 30 days (for Foundayo) or every four weeks (for Zepbound) as the body adjusts. This titration process helps minimize side effects while allowing women to find their optimal maintenance dose.

• Foundayo Dosing: Starts at 0.8 mg daily and increases through 2.5 mg, 5.5 mg, 9 mg, 14.5 mg, and up to 17.2 mg daily over approximately six months, with recommended maintenance doses of 5.5 mg, 9 mg, 14.5 mg, or 17.2 mg depending on individual response
• Zepbound Dosing: Starts at 2.5 mg weekly and increases through 5 mg, 7.5 mg, 10 mg, 12.5 mg, and up to 15 mg weekly over approximately six months, with recommended maintenance doses of 5 mg, 10 mg, or 15 mg depending on individual response
• Dose Adjustment Flexibility: Women experiencing unpleasant side effects can request delayed dose increases to allow their bodies more time to adjust, as some women may need longer than others to reach their maintenance dose

It's important that women never change their dose without consulting their prescriber, as dose timing and escalation are carefully designed to balance effectiveness with tolerability .

What About Side Effects and Cost for Women?

Both medications share similar side effects because they're both GLP-1 drugs. Women may experience nausea, diarrhea, constipation, vomiting, abdominal pain, belching, heartburn, headache, bloating, fatigue, and gas. Zepbound users may also experience injection site reactions at the point where they administer the weekly shot .

Cost is another significant consideration for women without insurance coverage. Foundayo ranges from $149 to $299 per month depending on dose, with a special pricing structure that requires refilling within 45 days to access the lowest price for higher doses. Zepbound costs substantially more, ranging from $299 to $449 per month for vials or pens, or $1,086.37 for a full pen, making it a considerably larger financial commitment .

For women deciding between these two options, the choice ultimately depends on personal priorities. Those prioritizing maximum weight loss results and willing to commit to weekly injections may find Zepbound's superior efficacy worth the higher cost and injection requirement. Women who prefer daily oral medication and have a lower budget may choose Foundayo, understanding that weight loss results will be more modest. Discussing these trade-offs with a healthcare provider can help women select the medication that best aligns with their health goals and lifestyle.