Here is an email that our Chaplain just sent out about this:
Ash Wednesday is a day of total abstinence from meat and a day of fasting.
FASTING: Catholics who are 18 year old and up, until their 59th
birthday (when you begin your 60th year), are bound to fast (1 full
meal and 2 “snacks” that don’t add up to a full meal) on Ash Wednesday
and Good Friday.
ABSTINENCE: Catholics who are 14 years old and older are abound to
abstain from meat on Ash Wednesday and on all Fridays of Lent. In
fact, ALL Fridays of the year require penance, and the classic penance
is abstinence from meat.
In general, when you have a medical condition of some kind, or you are
pregnant, nursing, etc., these requirements can be relaxed. God does
not ask the impossible of us, but this is a deep part of our faith.