For many Americans struggling to lose weight, powerful new medications are changing the game. With roughly 40% of U.S. adults living with obesity, according to the Centers for Disease Control and Prevention, the demand for effective treatments has never been higher. Two groundbreaking “weight loss shots” — semaglutide (known by brand names like Ozempic or Wegovy) and tirzepatide (Mounjaro or Zepbound) — have emerged as highly effective weight loss medications. A pill version of Wegovy became available in January, and more recently, orforglipron (Foundayo) was approved, which also offers the convenience of a once-daily pill.
Orforglipron, semaglutide and tirzepatide work by mimicking natural gut hormones to help manage Type 2 diabetes and promote significant weight loss. But they work in slightly different ways. The difference in how they target the body’s hunger and fullness signals is key to understanding the potential weight loss differences between them.
[READ: Supplements for GLP-1 Users: Essential Vitamins, Protein and Side Effect Relief]
How They Work: GLP-1 and GIP Hormones
Both orforglipron and semaglutide are single-action drugs, mimicking the GLP-1 (glucagon-like peptide-1) gut hormone. Tirzepatide, on the other hand, is a dual-action drug, mimicking both GLP-1 and GIP (glucose-dependent insulinotropic polypeptide).
Both GIP and GLP-1 are known as incretin hormones. They are secreted from the gut in response to food. These hormones regulate appetite, blood sugar and digestion.
What is GLP-1?
GLP-1 is a natural hormone released after meals, and it does a lot of good:
— Helps you feel full longer: It slows down how quickly food leaves your stomach.
— Curbs hunger: It signals to your brain that you are full, which helps reduce cravings and overall food intake.
— Manages blood sugar: It boosts insulin production and lowers glucagon (a hormone that raises blood sugar), making it particularly helpful for people with diabetes.
What is GIP?
GIP is another gut hormone released in response to food. Like GLP-1, GIP helps increase insulin and decrease glucagon. Research suggests that GIP also plays a role in burning energy and may even help prevent fat storage.
The power of 2: GIP and GLP-1
GIP and GLP-1 are believed to work together to be more effective. Experts suggest they act synergistically to increase the feeling of fullness (satiety), reduce how much you eat and boost weight loss.
According to Dr. Eiriny Eskander, a dual board-certified endocrinologist and internal medicine physician who works at Diabetes and Endocrine Specialists in Encino, California, this dual-action mechanism creates a more powerful and effective agent, leading to greater weight loss.
Since tirzepatide mimics both GLP-1 and GIP, it is more effective at reducing weight.
[READ: Exercising on GLP-1s: How to Stay Safe and Healthy]
Comparing Semaglutide, Orforglipron and Tirzepatide
| Orforglipron | Semaglutide | Tirzepatide | |
| Brand names |
— Foundayo |
— Ozempic — Rybelsus — Wegovy |
— Mounjaro — Zepbound |
| Targeted hormone(s) | GLP-1 | GLP-1 | GIP and GLP-1 |
| Available brand name forms |
— Oral pill |
— Injection pen — Oral pill |
— Injection pen — Injection vial |
| Most common side effects |
— Constipation — Diarrhea — Nausea |
— Nausea — Diarrhea — Vomiting |
— Nausea — Diarrhea — Constipation |
| Max weight loss % on average | 11% | 15% | 21% |
| Primary uses |
— Weight loss — Being investigated for Type 2 diabetes |
— Type 2 diabetes — Weight loss |
— Type 2 diabetes — Weight loss |
| Additional FDA-approved uses | None to date *Foundayo is currently being studied for sleep apnea, hypertension, osteoarthritis of the knee in obese adults and stress urinary incontinence in overweight adults |
— Reduce the risk of kidney decline in Type 2 diabetes — Reduce the risk of cardiovascular disease |
— Treatment of noncirrhotic metabolic dysfunction-associated steatohepatitis (MASH) — Sleep apnea |
Efficacy: Key Weight Loss Findings
Studies show orforglipron, semaglutide and tirzepatide can all lead to significant weight loss when combined with diet and exercise, with tirzepatide having higher average weight loss result. Here are the highlights of how they compare:
— Semaglutide (like Wegovy): In the STEP-1 trial, people who were overweight or had obesity (without diabetes) and took once-weekly semaglutide lost an average of 15% of their body weight over 68 weeks. This was much better than the 2.4% lost by the placebo group. Participants also saw improvements in heart health markers like blood pressure and cholesterol levels. In separate studies, the semaglutide pill was found to be as effective as the injection. People who took 25 mg of semaglutide orally lost approximately 14% of their body weight, compared with just 2% with a placebo.
— Tirzepatide (like Zepbound): The Surmount-1 trial, involving people with obesity or who were overweight (without diabetes), found that once-weekly tirzepatide led to an even greater weight loss. Depending on the dose (5 mg, 10 mg or 15 mg), participants lost an average of 15% to 21% of their body weight after 72 weeks. All doses outperformed the placebo.
— Orforglipron (Foundayo): The Attain-1 trial studied the efficacy of once-daily oral orforglipron in people with obesity (without diabetes). Participants who took orforglipron had an average weight loss of 11.1% compared with 2.1% with placebo. Participants also had improvements in blood pressure and cholesterol levels. At the highest doses, 36% of participants lost at least 15% of their body weight and 18% lost at least 20% of their body weight.
All these medications are effective weight-loss tools. However, in their respective trials, tirzepatide demonstrated a potentially higher maximum average weight loss (up to 21%) compared to semaglutide (up to 15%) and orforglipron (up to 11%).
[READ: Navigating Insurance Coverage for GLP-1 Medications: A Step-by-Step Guide]
Comparison of Side Effects and Safety
Semaglutide, orforglipron and tirzepatide can cause similar side effects, which are usually mild. When comparing semaglutide to tirzepatide, clinical trials of semaglutide and clinical trials of tirzepatide indicate that tirzepatide may be better tolerated. Side effects occurred more frequently among participants receiving semaglutide.
The most common side effects associated with GLP-1s are gastrointestinal-related. During clinical trials, these side effects were mostly mild to moderate and temporary, typically occurring during dosage increases.
During the Surmount-5 clinical trial, which compared semaglutide to tirzepatide for weight loss, more patients who took semaglutide discontinued treatment due to side effects than those who took tirzepatide. Also, people who received semaglutide were more likely to have vomiting.
The ACHIEVE-3 trial compared oral orforglipron to oral semaglutide for Type 2 diabetes. Gastrointestinal-related side effects were most common but occurred more frequently in those who received orforglipron. Also, more orforglipron participants discontinued treatment due to gastrointestinal-related side effects.
“People are very worried about potential side effects, but even at the highest dose, about 95% to 96% of patients can tolerate the medicine,” adds Dr. Disha Narang, an endocrinologist and director of obesity medicine at Endeavor Health in Chicago.
Eskander says that at her practice, she finds that patient better tolerate tirzepatide.
[READ: What to Know About the New Wegovy Pill]
Serious side effects
GLP-1s can cause more serious side effects, though these are less common.
Rapid weight loss, along with slowed digestion, can increase the risk of gallbladder inflammation and gallstones. This risk is increased at higher doses and during long-term treatment. Gallstones can block the gallbladder opening, the cystic duct or the bile ducts. This causes bile to back up into the gallbladder, causing inflammation, pain, nausea and vomiting. This can lead to complications such as pancreatitis and sepsis.
People taking orforglipron, semaglutide and tirzepatide have developed acute pancreatitis, a sudden inflammation of the pancreas, which can lead to organ dysfunction, organ failure and even death. Although pancreatitis rates were low in clinical trials, individuals with a history of pancreatitis should avoid GLP-1 receptor agonists.
All GLP-1s, including orforglipron, semaglutide and tirzepatide, carry boxed warnings regarding the risk of thyroid C-cell tumors, also known as medullary thyroid cancer. Boxed warnings are assigned by the Food and Drug Administration and highlight serious drug-related risks.
In clinical studies, both semaglutide and tirzepatide caused tumors in thyroid C-cells of rats. These tumors were more likely to occur with high-dose, long-term treatment. Results are inconclusive as to whether this increases the risk in humans. However, because of this possible risk, people with a personal or family history of medullary thyroid carcinoma and those with multiple endocrine neoplasia syndrome type two should not use GLP-1 medications.
Orforglipron is not pharmacologically active in rats and did not produce thyroid C-cell tumors in preclinical studies; however, the same boxed warnings and contraindications apply, and it should still be avoided by those who are at an increased risk.
Also, those with gastroparesis, or delayed stomach emptying, should avoid GLP-1 medications as they could worsen this condition.
Eskander says that she has noticed that GLP-1 medications can also cause acid reflux, and she avoids prescribing GLP-1s in those with severe acid reflux or gastrointestinal conditions.
[READ: Best Medicines for Heartburn, Nausea and Digestive Issues]
Which One Is Right for You?
When choosing a weight-loss medication, it is important to have a detailed discussion with your health care provider. Together, you should review your current medications, health history and weight-loss goals to develop a treatment plan.
Narang adds that she has seen significant success with either medication, and it is not a one-size-fits-all approach. While Foundayo is new, its results look promising.
Choosing between orforglipron (Foundayo), semaglutide (Wegovy, Ozempic, Rybelsus) and tirzepatide (Zepbound, Mounjaro) for weight management involves practical considerations beyond just efficacy. Here’s a breakdown of key factors to help you and your doctor decide:
Administration: injection vs. pill
— Both drugs offer a once-weekly injection in the abdomen, thigh or upper arm, requiring site rotation and refrigeration.
— If you prefer a pill over an injection, orforglipron (Foundayo) and the daily Wegovy pill are currently your only (non-compounded) options. While the Wegovy pill comes with strict timing requirements, Foundayo does not. A daily pill version of Zepbound is expected to come to market later in 2026. The pill does not require refrigeration.
Wegovy pill vs. Foundayo
If you want to avoid weekly injections, your two primary non-compounded oral options are the Wegovy pill (oral semaglutide) and the newly approved Foundayo (orforglipron). While both offer the convenience of a once-daily tablet, they differ significantly when it comes to your daily routine and expected results.
Daily Routine and Food Restrictions:
The biggest practical difference is how these pills fit into your morning. The Wegovy pill comes with strict timing rules: You must take it first thing in the morning on an empty stomach with a tiny sip of water, then wait before eating, drinking or taking other medications.
In contrast, Foundayo can be taken at any time of day without food or water restrictions, notes Narang, because its nonpeptide structure makes it more stable in the gut compared with oral semaglutide and doesn’t rely on a perfectly empty stomach to be absorbed.
Weight Loss Efficacy:
Both options deliver impressive results, though oral semaglutide has a slight statistical edge. Clinical trials show that patients taking the 25 mg Wegovy pill lost an average of about 14% of their body weight. In comparison, the Attain-1 trial for Foundayo showed an average weight loss of 11.1%, though it is worth noting that over a third of participants on the highest doses of Foundayo achieved a 15% or greater weight reduction.
Side Effects:
Like all GLP-1 medications, both tablets can cause nausea, diarrhea, constipation and vomiting. However, head-to-head data from the ACHIEVE-3 trial indicates that Foundayo may be tougher on the digestive tract; gastrointestinal side effects were more frequent with Foundayo, leading to a higher rate of patients stopping the medication altogether compared to oral semaglutide.
Out-of-Pocket Cost: If your insurance doesn’t cover weight loss medications, pills are generally much friendlier to your wallet than injectables. Foundayo lists at $149 to $299 per month; the Wegovy pill is similar, at $199 to $299 per month.
Dosage
— All medications are started at a low dose and gradually increased (titrated) typically every four weeks to minimize side effects.
— Tirzepatide and orforglipron have more strengths, meaning more steps to reach the highest dose, which could mean a slower adjustment if you need the maximum strength
Cost and Coverage
— GLP-1 medications are expensive, and many insurance plans do not cover them, often requiring prior authorization if they do. Coverage is more likely if you have a condition like Type 2 diabetes or cardiovascular disease.
— Without insurance, tirzepatide is generally more expensive than semaglutide. Foundayo and the Wegovy pill are comparable in price and offer the lowest entry price.
Bottom Line
Semaglutide, orforglipron and tirzepatide are all highly effective weight-loss medications. Both slow digestion and reduce appetite and cravings. They also share similar side effects
Clinical trials have shown that tirzepatide produces greater weight loss than semaglutide and orforglipron, but for those paying out of pocket, it is more expensive. Semaglutide can reduce the cardiovascular risk in people with cardiovascular disease and provides benefits for kidney and liver health. Tirzepatide can improve sleep apnea, but it is only available as an injection, whereas semaglutide is also available as a convenient daily tablet.
Foundayo offers the convenience of a once-daily pill, without the restrictions of the oral semaglutide option. Foundayo is also available at a better price point than injectables and has shown promise in clinical trials for Type 2 diabetes.
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Semaglutide vs. Tirzepatide vs. Orforglipron for Weight Loss originally appeared on usnews.com
Update 07/07/26: This story was published at an earlier date and has been updated with new information.
