How can I resolve the "Cannot connect to the iTunes Store" error?

This is a bug from Apple's App Store, not the Weight Loss app itself, but you may see the alert message for this bug during the process of purchasing or restoring this app.

In order to resolve this issue, please see the official answer from Apple by taking a look at steps #1 - #4 at the link below:

https://support.apple.com/en-us/HT201400