Hi felicitas272,
Welcome to Apple Support Communities. We understand that the Health app is consuming a large percentage of the battery life on your iPhone.
Having a peace of mind that your iPhone is delivering optimal battery performance is vital. We'll be happy to help.
Our recommendation is to adjust the settings on your iPhone to help maximize the battery performance. Here's a helpful article with the proper steps:Â Maximizing Battery Life and Lifespan. If you make any changes to your device, please charge the phone to 100% and then test for 48 hours to see if you notice an improvement.
In addition, you'll want to ensure that your iPhone is on iOS 14.0.1. Updating to the latest software version can help:Â Update your iPhone, iPad, or iPod touch. Please charge the phone to 100% after updating and then test for 48 hours to see how the battery performs.
Kind regards.