The Messenger of Allah (blessings and peace of Allah be upon him) said to us: “O young men, whoever among you can afford it, let him get married, for it is more effective in lowering the gaze and guarding one’s chastity. And whoever cannot afford it should fast, for it will be a shield for him.” Sheikh according to this hadees can single man fast whole days or 15 days
Sep 27th, 2020
You can fast as long as this prevents you from falling into sin and the best it to fast alternate days. If this doesn’t stop, you can fast everyday.