Note: This is appropriate for Tisha B'Av or Yom Kippur, but
not for the other fast days.
Starting two days before the fast, in the morning (e.g. if
the fast is on Shabbos this means Thursday morning) through
the day before the fast in the afternoon (e.g. Friday
afternoon) one should drink large quantities of water. For
example, someone who normally drinks 10 glasses of water per
day should drink an extra five on Thursday, and on Friday he
should drink 10 cups before noon and finish the rest of the
additional water at least 20 minutes before starting
Seudah Mafsekes.
The same applies regarding protein consumption. Starting
Thursday morning, one should increase one's normal intake by
50 percent over the normal amount, which is 1 gram per day
for every kilogram of body weight.
For example, a person who weighs 70 kg should eat 70 grams of
protein on a normal day, and on Thursday he should eat 105
grams of protein and another 105 grams of protein on Friday,
including Seudah Mafsekes.
The protein content (chelbon in Hebrew) appears on the
label of most food products. A normal egg has eight grams of
protein and a serving of fish, poultry or beef has 20-35
grams of protein, depending on the serving size.
On Friday (as every day) one should also avoid drinking 20
minutes before meals and two hours after meals (including
Seudah Mafsekes) as I wrote in my booklet, Chaim
Bri'im Kehalochoh. Thus one should use foresight and
planning in his eating and drinking during these two
days— hechochom einov berosho.
During Seudah Mafsekes one should be careful to chew
well and not overeat, of course. The strength to fast will
come from thorough chewing and protein, not from the amount
eaten.
All year long, one should use salt sparingly, especially
before a fast.
