Islam: Fasting is not compulsory on unbelievers.
2- Maturity: Fasting is not compulsory on children, but they may be ordered or encouraged to fast if they have the ability, so that they may become acquainted with it.
3- Sanity: Fasting is not compulsory on the insane.
4- Ability: Fasting is not compulsory on whosoever is too incapacitated to fast.