As well, for one to be obligated to fast, he must be of sound mind. Fasting is not obligatory on the insane person.
Fasting is not obligatory on a person whose body cannot tolerate fasting, either due to old age or because of a severe illness. Moreover, if a person would be harmed by fasting, that is, because of his fasting his sickness would get worse, or he would die, then fasting is prohibited for him. The one who does not fast because of old age or an illness he is not hopeful to be cured of does not have to make up the missed days of fasting. Instead he pays an expiation to a poor Muslim for every day he missed of fasting. The expiation is two average-sized, cupped hands of the most common staple food of the country, which in this country, is wheat.