Nowadays, before a fast day, it is very common for people to take a supplement known as Kalei-Tzom. Here in Eretz Yisroel, they are sold in shuls, shops and everywhere in between and they make you feel like they are something everyone must take. Normally the way it works is, that one takes them the day before a fast and it officially makes the fast much easier. When erev Tisha B’Av falls on Shabbos however, the question arises if they may be taken on Shabbos. The question is really two-fold: 1) Does it fall into the gezeirah [enactment] against taking medicine on Shabbos, where we normally say that there is an enactment against taking medicine on Shabbos as we are concerned one might come to grind spices (שחיקת סממנים )? 2) Is it a problem of preparing on Shabbos for the weekday (הכנה)?
The Gezeirah Against Taking Medicine on Shabbos
Regarding the issue of taking medicine on Shabbos, it’s difficult to say that there is a heter of machol beriyim as in the end of the day during a normal day one doesn’t consume such supplements, and the only time one takes them is before a fast. There is a dispute as to how the Kalei-Tzom supplement actually works, some say it slows down the digestion of the food one has eaten, and it causes it to get digested over a longer period of time, and as a result it makes one feel full and satisfied for longer, and some say the way it works is merely psychological, and really the supplement doesn’t do anything. According to the first approach, it would be forbidden to take on Shabbos due to the gezeirah against taking medicine on Shabbos, however, according to the second approach there would be more room for leniency.
Preparing on Shabbos for After Shabbos
In regard to the issue of preparing on Shabbos for after Shabbos there is what to discuss. Although one is allowed to go to sleep on Shabbos even if his intention is to be awake on motzei Shabbos (such as when Shavuos falls on motzei Shabbos) provided he doesn’t speak out explicitly why he is going to sleep (see Mishnah Berurah 290:4), therefore, in our case as well, just like one is allowed to eat lots of food on Shabbos so that he has strength for the fast, one should also be allowed to swallow Kalei-Tzom pills before the fast to make the fast easier. However, there is a big difference between the cases, as when one eats regular food or goes to sleep, it’s not clear from the act one is doing that he is preparing for after Shabbos, however, when swallowing a Kalei-Tzom pill, it’s clear from the act what he is doing. Afterall, the name “Kalei-Tzom”, literally means, a pill to make the fast easier, therefore, it may well be worse. Based on this, R’ Elyashiv (and R’ Sroya Davlitsky in his sefer, Dinei Tisha B’Av Shechal B’Yom Rishon, sif 76) ruled that it is forbidden to take such supplements on the Shabbos before Tisha B’av due to the issur of hachonah [preparing on Shabbos for weekday].
The Opinion of the Ba’al Machzeh Eliyohu (R’ Pesach Eliyohu Falk zt”l)
However, the Machzeh Eliyohu (cited in Kol Torah, Kovetz 61, pg. 63, ois 10) writes that there are many proofs that the prohibition to prepare on Shabbos for weekday is only when doing a positive act of hachonah (הכנה חיובית), however, there is no problem of hachonah if one is doing an act merely to save something or to stop something from getting wasted/ruined completely or even partially (see Shu”t Machzeh Eliyohu Vol. 1, siman 54 for proofs).
The explanation for this is: Preparing on Shabbos for weekday is a disgrace to Shabbos, as on Shabbos one shouldn’t be busying himself with doing things for the week. However, when it comes to doing an act to save something, since there is no other choice but to do it now, it’s not considered a disgrace to Shabbos, as after all, when else can it be done. According to this, taking a supplement on Shabbos to make the fast on motzei Shabbos easier wouldn’t be a problem of hachonah, as there is no other time to do it. If one doesn’t take the supplement now on Shabbos, he will be thirsty the next day, and the only time to do it is now, therefore, there is no problem of hachonah. However, the Machzeh Eliyohu concludes: Although one may take such supplements and there is no problem of hachonah, taking such things to make the fast easier, when one is easily able to fast without them and he is simply taking it to make the fast even easier, is not acting correctly.
