Back up your Health data on iPhone
If you use iCloud (see Sign in with your Apple ID), your health and fitness information in the Health app is stored automatically in iCloud. Your information gets encrypted as it goes between iCloud and your device and while it’s stored in iCloud. In addition to using iCloud, or if you aren’t using iCloud, you can back up your Health data by encrypting an iTunes backup. See Back up iPhone using iCloud.
Stop storing your Health data in iCloud
Go to Settings > [your name] > iCloud, then turn off Health.