Prophet Muhammad (pbuh) said:

Praise be to Allaah

The beloved Messenger of Allaah and Our beloved Prophet Muhammad(صلى الله عليه و سلم) said:
“The difference between our fasting and that of the people of the book is taking the meal of suhoor.” (Saheeh Muslim)

Even taking a cup of water instead of a meal for suhoor has blessing in it, too.

Al-Bukhaari (1921) narrated from Anas that Zayd ibn Thaabit said: “We ate suhoor with the Prophet (sallAllahu 'alyhi wasallam), then he stood up to pray.”I [Anas] said: “How long was there between the adhaan and suhoor?” He said: “As long as it takes to recite FIFTY verses.”
So to fast in Ramadhaan, it is obligatory to make the intention during the night sometime before the arrival of Fajr of the day being intended to fast. A Muslim's rising up from sleep in the last part of the night and eating the sahoor is an indication of the presence of the intention. It is not required that a person utter the intention by the tongue by saying: "I intend to fast". This is an innovation (bid`ah) and is not permissible. The intention in Ramadhaan is to be done every day (for the next days fast) because each day is a separate act of worship requiring its intention. So the intention for the fast is to be made in the heart for everyday during the night. If someonemakes the intention during the night, then sleeps and does not wake up until after the time of Fajr has entered, then his fast is valid due to the presence of the intention from the night.
Shaykh Ibn Fowzaan
Fataawa Ramadhaan - Volume 1, Page 162, Fatwa No. 95;