Muslims fast thirty days during the month of Ramadan. This is in accordance with this teaching in the Quran.
002.183 – 184
PICKTHAL: O ye who believe! Fasting is prescribed for you, even as it was prescribed for those before you, that ye may ward off (evil); (Fast) a certain number of days; and (for) him who is sick among you, or on a journey, (the same) number of other days; and for those who can afford it there is a ransom: the feeding of a man in need – but whoso doeth good of his own accord, it is better for him: and that ye fast is better for you if ye did but know –
Dialog: Christians can also share with their Muslim friends that fasting is also taught by Jesus and practiced by Christians.
(Mat 6:17-18 NIV) But when you fast, put oil on your head and wash your face, {18} so that it will not be obvious to men that you are fasting, but only to your Father, who is unseen; and your Father, who sees what is done in secret, will reward you.
The difference is that Christians do not have a specific time of the year to fast.
In Islam there is a provision that those who can afford it need not fast, if only they would feed a poor person.