Darkoshi

It isn't enforced, actually - but a good Muslim does do it. The reason Muhammad (pbuh) established Ramadan was to make sure Muslim society had experience with deprivation, so they would be more merciful to the poor. The pagan society Muhammad (pbuh) revolted against was wealthy, sophisticated and urban. They despised and abused the poor, especially widows and orphans. Muhammad (pbuh) always had special concern for widows and orphans. The reason Muslim men can have up to four wives was to get widows off of the streets and cared for. Travelers, the sick and the aged are not encouraged to fast.