The Church does not officially promote the concept of 'cheat days' during Lent. However, Lent is traditionally considered 40 days long, even though the time between Ash Wednesday and Easter is actually 47 days. This is because Sundays are not considered part of Lent.
Are you allowed to have what you give up for Lent on Sundays?
This is because the Sundays of Lent aren't “prescribed days of fast and abstinence” by the church. Basically, it means that it's up to the individual to continue abstaining from the item or act of their choosing on Sundays.
What are the rules during Lent?
A summary of current practice:
- On Ash Wednesday, Good Friday, and all Fridays of Lent: Everyone of age 14 and up must abstain from consuming meat.
- On Ash Wednesday and Good Friday: Everyone of age 18 to 59 must fast, unless exempt due to usually a medical reason.