For members of the Latin Catholic Church, the norms on fasting are obligatory from age 18 to 59. When fasting, a person is permitted to eat one full meal. Two smaller meals may also be taken, but not to equal a full meal.
The norms concerning abstinence from meat are binding upon members of the Latin Catholic Church from age 14 onwards.
More information on Fast and Abstinence may be found here.
Lent rersources from the USCCB