Cagrilintide Plus Semaglutide Beat Semaglutide Alone for Weight Loss in Obesity

CATEGORY: DIET & WEIGHT

Would two appetite hormones do more than one? A weekly injection pairing cagrilintide–semaglutide reduced body weight by an average of 20.4% over 68 weeks in a randomized trial of 3,417 adults with obesity or overweight, against 3.0% with placebo. More than half the people taking it lost at least a fifth of their body weight.¹

Two Fullness Signals Instead of One

The combination joins copies of two natural hormones. Semaglutide mimics GLP-1, which the gut releases after eating to tell the brain you are full and to slow the stomach’s emptying. Cagrilintide mimics amylin, a second fullness hormone released by the pancreas alongside insulin. The researchers’ stated reasoning was that the two molecules act on different appetite-control regions of the brain, so their effects ought to add rather than overlap. Think of turning down both the thermostat and the space heater instead of only one. REDEFINE 1 put that expectation to a direct test by running each medicine alone as its own comparison group.¹

Sixty-Eight Weeks, Four Groups, One Random Draw

Researchers in 22 countries enrolled 3,417 adults without diabetes who had obesity, or overweight plus at least one weight-related health problem. They averaged 47 years of age and weighed 106.9 kilograms at the start, about 236 pounds. A blinded random draw placed each of them in the weekly combination injection group (2,108 people), semaglutide alone (302), cagrilintide alone (302), or placebo (705). Every group also got diet and physical-activity counseling. Doses climbed over 16 weeks and then held steady for a year while the trial tracked body weight, waist size and blood pressure.¹

A Fifth of Body Weight, and More Than Its Parts

At 68 weeks, weight was down an average of 20.4% on the combination against 3.0% with placebo. The pairing also beat its own ingredients, by 5.5 percentage points over semaglutide alone and 8.9 over cagrilintide alone, which is what the researchers had posited. More than half the combination group (53.6%) lost at least 20% of body weight, roughly one in three (34.7%) lost a quarter or more, and about one in five (19.3%) lost 30% or more. On placebo, fewer than 2% reached even the 20% mark. Among those who stayed on treatment, average loss came to 21.6 kilograms, close to 48 pounds. Waistlines shrank by 13.4 centimeters more than with placebo and systolic blood pressure fell 6.7 millimeters of mercury more. The cost was mostly digestive. Nausea, vomiting, diarrhea and constipation affected 79.6% of people on the combination versus 39.9% on placebo, though the trial describes them as mainly mild to moderate and passing, clustered around dose increases. Serious adverse events reached 9.8% of the combination group versus 6.1% on placebo, and 5.9% quit the medicine over side effects.¹

Where It Lands Among the Newest Options

That average sits at the top of the range set by existing randomized trials of weight-loss medicines. In a head-to-head trial of 751 adults with obesity, tirzepatide produced an average 20.2% loss over 72 weeks against 13.7% for semaglutide alone.² The combination remains investigational. It is under regulatory review and not yet available, so its results describe what the medicine did under study conditions rather than something now sitting on pharmacy shelves.

Key Takeaways

• A weekly combination injection cut body weight by an average of 20.4% over 68 weeks against 3.0% with placebo, and 53.6% of those taking it lost at least a fifth of their body weight.
• The pairing outperformed each of its two component medicines given alone, matching the researchers’ expectation that the two hormone signals would add up.
• Digestive side effects were common, 79.6% versus 39.9% on placebo, though mostly mild to moderate and temporary; 5.9% stopped treatment because of them.
• The medicine is not approved yet, and its average result sits alongside the 20.2% seen with tirzepatide, the most effective approved medicine in a comparable randomized trial.

References

1. Garvey WT, Blüher M, Osorto Contreras CK, et al. Coadministered Cagrilintide and Semaglutide in Adults with Overweight or Obesity. New England Journal of Medicine. 2025;393(7):635–647. link
2. Aronne LJ, Horn DB, le Roux CW, et al. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity. New England Journal of Medicine. 2025;393(1):26–36. link