Q&A: Eating and Drinking on the Ninth
Eating and Drinking on the Ninth
Question
Hello Rabbi, may you be sealed for a good year.
I occasionally practice what is called a "water fast" for two or three days. I won’t go into the details of its beneficial effects, but in principle it puts the body into ketosis and can also affect how easy an actual fast feels. My question is: what about someone who wants to do a water fast in the days before Yom Kippur, in terms of the requirement to eat on the ninth?
One reason I’ve seen given for eating is to make the fast easier—and then eating on the ninth could seemingly make it harder. Another reason I’ve seen given for eating is דווקא to make the fast harder—and then specifically the water fast would make it easier, which according to that reason is not desirable.
Another related question: what about a person who is on a diet and does not want to eat bread and the like at the Sabbath meals?
Answer
We do not derive the law from the reason given for the verse. Eating on the ninth is a Torah-level obligation according to most opinions, so it should not be interpreted based on its reasons.
On the Sabbath one should eat bread. Eat an egg-sized amount at two meals, and that’s it. It won’t ruin your diet.