If a person was eating a meal with bread, which requires reciting Birkat Ha’mazon, and after initially deciding he had eaten enough he then changes his mind and wishes to eat more food, must he recite a Beracha over that food? One might argue that his decision to end his meal constitutes a "Hefsek" (interruption), such that his new decision to resume eating would require a new Beracha. According to this rationale, even though he has yet to recite Birkat Ha’mazon, the new food he wishes to eat is not covered by the Beracha he recited at the beginning of his meal, and he must therefore recite a new Beracha.
This issue is subject to a debate among the Rishonim (Medieval Halachic authorities). It appears from Tosafot, the Rosh and the Tur that an unspoken decision to end one’s meal does not signify the end of the meal according to Halacha. Simply deciding in one’s mind not to eat more food does not, according to this view, mark the formal end of his meal such that he would recite a new Beracha if he chooses to resume eating. It is only if a person verbally expressed his decision to end the meal – such as by saying, "Let us recite Birkat Ha’mazon" – or if he washed Mayim Aharonim, that his meal has ended and he would be required to recite a new Beracha if he chooses to resume eating. But if he simply thought in his mind that he does not wish to eat anymore, then if he changes his mind he may eat without reciting a new Beracha.
This appears to be the view accepted by the Shulhan Aruch, who writes that a person who wishes to eat after having verbally expressed his desire to recite "Birkat Ha’mazon," or after washing Mayim Aharonim, must recite a new Beracha. This obviously implies that otherwise, if a person merely thought in his mind that he wants to end the meal and recite Birkat Ha’mazon, he does not have to recite a new Beracha if he then changes his mind.
The Rambam (Rabbi Moshe Maimonides, Spain-Egypt, 1135-1204), however, disagrees with this position. In his view, even an unspoken decision to end the meal constitutes a "Hefsek," and a person who decided he would not eat more and then changes his mind would, in fact, be required to recite a new Beracha before resuming eating.
In light of this debate, and notwithstanding the Shulhan Aruch’s ruling, the Kaf Ha’haim (Rav Yaakob Haim Sofer, Baghdad-Israel, 1870-1939) writes that a person in this situation should first recite Birkat Ha’mazon. If one silently decided that he would not eat anymore, and then changed his mind, he should recite Birkat Ha’mazon so that all opinions would require him to recite a new Beracha when he resumes eating. If he eats before reciting Birkat Ha’mazon, then the Shulhan Aruch would not require him to recite a Beracha, whereas the Rambam would. It is best to avoid this question and recite Birkat Ha’mazon, after which he would be required to recite a Beracha before eating according to all Halachic authorities.
It must be emphasized that if a person verbally stated that he has finished his meal, or if he washed Mayim Aharonim, and then he decides to resume eating, then he must recite a new Beracha according to all views. (In truth, however, one should in any event recite Birkat Ha’mazon immediately after washing Mayim Aharonim, and not eat anything in between.)
Summary: If a person was eating a meal and decided he had eaten enough, and he then changes his mind and wishes to continue eating, he should first recite Birkat Ha’mazon, and then eat with a Beracha. Since there are differing views as to whether he would have to recite a Beracha if he eats before Birkat Ha’mazon, it is best to simply recite Birkat Ha’mazon, and then eat with a Beracha.
