It is to be noted that suhoor is a “mustahab” practice, it is neither “wajib” nor “farz”, therefore, even if someone skips suhoor, their fast will be deemed valid. However, for a qaza fast, one should make the intention to fast the night prior or at least before subah sadiq (the break of dawn) occurs. In essence, if someone does not make the intention to fast (in the case of a qaza fast) before subah sadiq occurs, their fast will be deemed invalid.