One of the options to create and also sign in to Lifesum is using the option to log in with your Apple ID in two different ways:

- showing your actual email address connected to your Apple ID under Settings/Account Settings in Lifesum

- using Apple’s private email relay service and hiding your email address under Settings/Account Settings in Lifesum (the field will show an email address created by Apple ending with * (emails will then be routed to the Apple ID’s verified email address)

The email address you are using for Lifesum can be found under Settings > Apple ID > Password & Security > Apps Using Your Apple ID > Lifesum

Please find more information here: