This research study is testing a medicine called CagriSema to help people with obesity lose weight and keep it off. Obesity means having too much body fat. The study has two parts:

1. **Main Study**: Participants randomly receive either CagriSema or a placebo (a fake pill with no medicine). You're twice as likely to receive CagriSema.

2. **Extension Study**: If you got CagriSema first, you'll continue with it at a random dose. If you got the placebo, you'll switch to CagriSema. The study lasts about 3 years and 3 months, with weekly injections.

To join, you must be 18 or older, have a Body Mass Index (BMI) of 30 or more, and want to lose 25% of your weight in 80 weeks. You can't join if you have diabetes or high blood sugar levels.

• The study takes about 3 years and 3 months to complete.
• Participants will have weekly injections.
• Participants may receive CagriSema or a placebo, with a higher chance of receiving CagriSema.