Based on a Naaleh.com shiur by Rabbi Ari Jacobson
The Gemara teaches us, based on the verse in Vayikra, “Lo tochlu al hadam,” that one may not eat or drink before Shacharit. The Kitzur Shulchan Aruch writes that one who does eat is referred to in the verse, “You have cast me behind your back.” In Hebrew, the word gabecha (back) can be interchangeably read as geyecha (arrogance). Tending to one’s own physical needs prior to acknowledging the source of one’s sustenance is haughtiness in one of its highest forms.
The accepted ruling in the Shulchan Aruch is that one may drink water before praying. Similarly, someone who is very weak and will be unable to have minimal concentration may eat before davening. However, at the very least, one should recite birkot hashachar beforehand. The majority of halachic opinions permit drinking coffee or tea if a person needs it to concentrate in prayer. The Mishna Berura prohibits adding milk or sugar as one may only drink what is minimally necessary. However, Rav Shlomo Zalman Auerbach writes that in our times when most people can afford milk and sugar and are generally accustomed to it daily, it is permitted. Going beyond this and having a cappuccino or a double vanilla shake is prohibited. The Kitzur writes further that someone who is old or weak and cannot wait till the end of davening on Shabbat and Yom Tov, when the prayers are lengthy, should daven Shacharit at home, make kiddush and eat something, and then go to shul for Mussaf.
How do these halachot apply to women? The Mishna writes that women are obligated to pray because they need Hashem’s mercy too. The Rambam holds that the Torah obligation of tefilah is to pray once a day in any language as long as it includes praise, supplication, and thanks. The specific text and times are d’rabanan. The Ramban disagrees and states that tefilah on a daily basis is completely d’rabanan. Only in times of distress does prayer becomes a Torah obligation.
The Magen Avraham notes that women in ancient times who would pray a tefillah in their own language were relying on the Rambam. Some modern day poskim continue to argue that women can fulfill their obligation with a short prayer that includes praise, supplication, and thanks. Others say that they must recite the Shemonei Esrei of Shachrit and Mincha daily. The consensus among all poskim is that women are exempt from Maariv because this was originally voluntary for men.
Rav Shlomo Zalman rules that the halachot of eating before davening apply equally to women. Therefore, a woman must pray before eating unless she is weak or infirm, in which case a man would be exempt too. On Shabbat, a woman should daven whatever prayers she is accustomed to praying and then make Kiddush.
Many times, women who are busy with their family may make it to shul late on Shabbat. If a woman arrives when the tzibbur is already davening Mussaf, she should daven Shacharit first. Rav Akiva Eiger writes that women may be exempt from Mussaf. This is because even though Shacharit and Mincha have an element of sacrificial services, they are mainly an expression of compassion. However, Mussaf strictly corresponds to sacrifices. Since women did not contribute to the half shekel and did not participate in the sacrifices, there is a machloket whether they are obligated to pray Mussaf at all. Therefore, for women, Shachrit takes precedence over Mussaf.