According to Canon Law, Roman Catholics are required to abstain from meat (defined as all animal flesh and organs, excluding water animals) on Ash Wednesday and all Fridays of Lent including Good Friday. Ash Wednesday and Good Friday are also fast days for Catholics ages 18 to 60, in which one main meal and two half-meals are eaten, with no snacking. Canon Law also obliges Catholics to abstain from meat on the Fridays of the year outside of Lent (excluding certain holy days) unless, with the permission of the local conference of bishops, another penitential act is substituted. Exceptions are allowed for health and necessity like manual labor and not causing offense when being a guest. The restrictions on eating meat on these days is solely as an act of penance and not because of a religious objection to eating meat. In 1966, the United States Conference of Catholic Bishops the conference of bishops has made substitution of a different penitential or charitable act an option for ordinary Fridays in their territory. After previous abolition, the Catholic Bishops' Conference of England and Wales restored the meatless ordinary Friday requirement for their territory effective September, 2011. A popular misconception is that Pope Gregory I (who ruled from 590 to 604, and who is also a canonized saint) declared that rabbits were not meat. This is apparently a corruption of a manuscript in which Saint Gregory of Tours described one person (who was also ill and might not have been Catholic) eating a rabbit fetus during Lent. The rules are widely ignored; a 2016 survey found that only 62% of U.S. Catholics said they avoid meat on Fridays during Lent.