Depending on the Jewish community to which they belong, some Jewish couples fast on the day of their wedding. Similar to the significant holiday Yom Kippur, this is done to atone for any sins. The couple may eat again after the jewish wedding ceremony.
Brides and grooms that I meet who want to speak with me before their wedding, want to learn about all of the traditions and elements of a Jewish wedding.
I had a couple recently meet me who had heard that they need to fast the day of their wedding. I wanted to present the facts and information to them to let them decide if this is something that they wanted to do and take on. I explained that according to Chabbad, that although it is not recorded in the Talmud, an ancient tradition advises bride and groom to fast on the day of their wedding. (This applies both to those who are marrying for the first time and to those who are remarrying.) They fast from daybreak until after the chuppah, eating their first meal during their yichud seclusion at the end of the ceremony.
Two reasons are advanced for fasting. First, tradition records that the sins of the bride and groom are forgiven on their wedding day. Because it is a day of forgiveness, it is considered a day of spiritual inventory and of repentance, akin to Yom Kippur—as represented by the fasting, the wearing of white, and the recitation of the confession at prayers (vidui and al chet).
The second reason is more practical, and halakhically more functional. The Sages sought to avoid the drinking of liquor before the wedding, as guests and relatives toast the future—it is a long way from stag nights, customary the world over, to the fast day of the traditional Jew. Unlike a Yom Kippur-type fast, which would require observance until nightfall, the wedding fast lasts only until after the chuppah, even if it takes place in the afternoon. It is not necessary to "make-up" the fast (hashlamah) on another day, in the event of a midday chuppah. Even though it is a personal fast, there need be no formal acceptance or vow to fast. If the chuppah is delayed beyond nightfall, and fasting becomes difficult, bride and groom may eat, but not drink intoxicating beverages. If even during the day the fast becomes too burdensome, they should discontinue it rather than arrive ill at the chuppah.
At the end of the day, the bride and groom that I met as their cantor to officiate their wedding, decided not to fast on their wedding day. The bride suffers from low blood pressure and was concerned about fainting or passing out. We all know that health in Judaism comes before fasting.
As a cantor who officiates Jewish wedding ceremonies I love teaching brides and grooms about the traditions surrounding Jewish wedding ceremonies - and the couples really appreciate learning.