Those between the ages of 18 and 59 are obliged to FAST (only one full meal).
The days of FAST (only one full meal) and ABSTINENCE (no meat) are Ash Wednesday and Good Friday. No dispensations are granted on these solemn days except for reason of sickness or those provided in canon law below.
The pastor of a parish has the faculty to give a dispensation to individual parishioners in his parish and the Diocesan Bishop alone has the authority to dispense groups of Catholics but only for a serious reason.