American Jews tend to prefer eating Shabbat lunch at noon or later. But especially once the clocks “fall back,” this schedule is problematic from both a halachic and practical standpoint.
Chazal seem to assume that the three required Shabbat meals (shalosh seudot) have defined times. The Mishnah states that if a fire breaks out on Shabbat, the amount of food that may be saved from the conflagration depends on the time of day: “If a fire started on Friday night, one may rescue food for three meals. On [Shabbat] morning, for two meals. On [Shabbat] afternoon, for one meal” (Shabbat 16:2).
Apparently, one Shabbat meal must be eaten on Friday night, the second in the morning (before halachic midday), and the third (seudah shlishit) in the afternoon (after minchah gedolah, half an hour past midday). Many Jews nowadays, however, miss the deadline for eating the second meal, particularly in the winter when chatzot can be as early as 11:40 a.m. in New York.
How do we explain this behavior?
Some Rishonim rule that the Mishnah doesn’t mean to imply that a Jew must eat the second meal in the morning. Rather, it’s simply describing the normal times of day that people eat their three Shabbat meals (see Ran, Shabbat 43b in the Rif). These Rishonim thereby justify what seems to have been a common practice in their days – to divide the morning meal into two rather than eat a separate third meal in the afternoon.
Tosafot, however, understands the Mishnah to require eating the third meal in the afternoon (Shabbat 118a s.v. “be’mincha”). The Shulchan Aruch rules accordingly (Orach Chayim 291:2). Apparently, Tosafot – whose opinion normative halacha reflects – maintains that each Shabbat meal must be eaten during the time period listed in the Mishnah.
However, Tosafot elsewhere seems to offer a contradictory opinion. In Mesechet Pesachim (101a s.v. “u’vkiddusha”), Tosafot indicates that one can fulfill the precept of shalosh seudot by eating all three meals on Shabbat day. If each meal, however, has a set time, why doesn’t Tosafot insist that one eat the first meal on Friday night?
Rabbi Moshe Mordechai Karp suggests a clever solution to this problem (Mishmeret Shabbat 16): Tosafot holds that of the three Shabbat meals, only the third one has a fixed time. In the Talmudic period, people normally ate two meals a day, one in the evening and one in the morning. Halacha mandates eating a third meal on Shabbat in honor of the day, so to emphasize this meal’s special nature, halacha requires that it be eaten at a time when people do not normally eat a meal – i.e., in the afternoon. The timing of all other meals is less strict.
Rabbi Karp buttresses his point by noting that the Talmud Yerushalmi prohibits fasting until midday on Shabbat (Taaniyot 3:11; codified in Shulchan Aruch, Orach Chayim 288:1). But if the second meal had to be eaten on Shabbat morning, as per the times given in the Mishnah, it wouldn’t be necessary to state that fasting is prohibited until midday.
The Rambam and others, however, do understand the Mishnah to be mandating specific times for all three meals of Shabbat. The Rambam writes: “One is required to eat three meals on Shabbat, one in the evening, one in the morning, and one in the afternoon” (Hilchot Shabbat 30:9; see also Teshuvot HaRashba 7:501 quoting Targum Yerushalmi).
The simplest explanation for why many early poskim do not mention a requirement to begin the second meal of Shabbat before midday is because it never occurred to them that anyone would act otherwise. People in earlier centuries ate a full meal before chatzot every day. So although the Rishonim mention the possibility of splitting the morning meal in two, no posek until recent times discusses eating two meals in the afternoon.
When it became common to eat a light breakfast and delay the day’s first major meal past midday, many people started to eat both the second and third meals of Shabbat in the afternoon. In the 19th century, we find the Aruch HaShulchan strongly encouraging people to begin the second Shabbat meal before chatzot (Orach Chayim 288:2), which would not have been necessary in earlier times.
Although it is certainly more correct to eat the second Shabbat meal before chatzot, those who are not careful to do so could claim they are relying on Rabbi Karp’s analysis of Tosafot and the Shulchan Aruch. However, one could also argue that nowadays, when people generally eat only a light breakfast on weekday mornings, one accords honor and distinction to Shabbat specifically by eating a full meal before midday!
An additional rationale for those who delay eating until the afternoon is as follows: Some poskim consider the possibility that one can fulfill the obligation to eat a Shabbat meal by consuming cake or cookies instead of bread (even if one does not eat a quantity of cake that requires saying hamotzi and birkat hamazon; if one eats such an amount, that undoubtedly constitutes a seudah).
As such, a “Kiddush” on Shabbat morning could conceivably count as the second Shabbat meal (see Hilchot Shabbat beShabbat 74:44, discussing the possibility that a subsequent full meal may actually be considered seudah shlishit). Indeed, attendance at a “Kiddush” in wintertime often means that one will not even get home, let alone begin the meal, before chatzot.
Of course, relying on eating cake is questionable; lechatchila, one should make sure to eat bread before chatzot. Furthermore, during the current pandemic, most regular “Kiddushim” have been canceled. Since people will likely not even have access to cake in a timely fashion, shuls must take extra care to conclude services early enough for people to walk home and begin the meal before midday. They must especially take care to do so next month on Shabbat Chanukah, when the tefillah is lengthy.
Eating the second meal early also allows for more time between lunch and seudah shlishit, assuring that the latter will be given its due attention and eaten with an appetite rather than forced down at the last moment before sunset purely out of halachic duty. If one is not ready for a large meal before chatzot, one can recite Kiddush, wash, and eat light foods immediately after davening (if one cannot stomach the thought of bread at all, one should at least eat cake, as discussed above). After minchah gedolah, one can wash again for seudah shlishit and eat such fare as cholent, kugel, and vegetables (preferably, one should daven Minchah first, but that is not strictly required).
Summary: It’s possible to justify the common practice to begin Shabbat lunch after midday. Conscientious individuals, however, should certainly take care to begin the second Shabbat meal before chatzot. If they do so, they both satisfy all halachic opinions and help ensure that seudah shlishit is eaten with an appetite.
 Rishonim disagree whether benching and then immediately making hamotzi again on Shabbat morning (or, indeed, any time) violates the prohibition of making an unnecessary berachah (berachah she’einah tzrichah). Some claim that the obligation to eat three meals means that the second hamotzi and benching by definition are not unnecessary berachot (Teshuvot HaGeonim Shaarei Teshuvah 148; see also Tur Orach Chayim 291, describing the Rosh’s custom). This issue is very relevant when Erev Pesach falls on Shabbat, as is scheduled to occur this year (5781).
 One avoids this prohibition of fasting by consuming anything before chatzot – even drinking water before Shacharit (cf. Aruch HaShulchan, Orach Chayim 288:1).
 Rabbi Karp entertains the possibility that the deadline for eating the second meal is minchah gedolah, not chatzot, which would explain why the Yerushalmi would have to tell us that fasting until chatzot is prohibited (Hilchot Shabbat beShabbat, ch. 74 n. 21). This suggestion is difficult to accept, but regardless, the Yerushalmi’s statement is not definitive proof that one need not eat the second meal before chatzot. Even if lunch must commence before midday, it is still reasonable to state that fasting before midday is prohibited for those people who won’t be eating a proper seudat Shabbat – for example, due to illness or a lack of access to bread.
 The Rambam apparently understands that the point of eating three meals at three different times is to experience enjoyment (oneg Shabbat) during each period of the day (Mishmeret Shabbat 16). Thus, according to the Rambam, it would seem that if one did not eat the Friday night meal, there would be no benefit to eating three meals on Shabbat day. Similarly, if one failed to eat the morning meal before chatzot, nothing would be gained by eating two meals in the afternoon.
 As the Aruch HaShulchan writes, it is technically sufficient to have just part of the meal (at least some bread) before chatzot. Similarly, one can begin seudah shlishit before midday as long as one continues and eats some bread after minchah gedolah (Mishnah Berurah 291:7). It would seem, though, that ideally the bulk of the seudah should be eaten during its proper time slot.
 Cf. Shabbat 119a, codified in Rambam, Hilchot Shabbat 30:8.