Sehri is not a condition for fasting; it is Sunnat. The Prophet (peace and blessings be upon him) partook of sehri and encouraged others to do it. He (pbuh) said: "Take sehri, for verily there is a blessing in sehri."
Hence always take Saheree food, even if very little or just a sip of water. Because it distinguishes us from other religions.
Sehri is a sunnah and to delay it is also a sunnah. This is what will strengthen the fasting Muslim, and would lessen the hardship of fasting. It would also lessen the time period of thirst and hunger.
Since Islam is based on easiness and has come with rules that make the acts of worship easy for people, a Muslim is advised to delay the sehri and hasten the Iftar (breaking the Fast) . So it is a sunnah for the fasting Muslim to get up for sehri and have something to eat, even if he or she would take a small edible thing like a date or a sip of water. If he or she does this, he or she would have done fulfilled the sunnah of the Prophet (peace and blessings be upon him).