There are six official fast days in the Jewish calendar. After a fast often people get sick when they eat. What type of food or drink is the best way to break the fast and avoid becoming ill?
The first thing I do is drink a large cup of water, and then wait. At least 5 minutes, 15 is better.
Usually after a fast you need water more than food, and by not eating you let the water absorb better. If you are feeling really weak, then also drink some (like 1/4 cup) grape or orange juice, to give some carbs with the water.
After waiting I have cake or any other carb, but not a protein. Along with juice or soymilk (again a carb - I would not do milk personally). But not too much!!! Not even enough for you to feel full. Grapes are good too - they are both water and carbs.
Let that digest for a while, half hour to an hour. Then you can eat a regular meal.
Note that the acidity of the orange juice may not agree with some people, you'll have to see how it works for you.
One should break a fast with easily digestible foods (which are usually not meat). One should rehydrate and eat easily digestible foods as well as foods that provide water and protein.
For starters, experts recommend that people break a fast (however long it be) slowly with foods that are easily digestible to help avoid gastrointestinal problems. Quickly consuming foods that are hard to digest and heavy in the stomach, such as bread, fried foods, full fat dairy products and of course meat, can make one feel ill.
Because of these biological changes, overeating immediately following a fast is much worse than overeating at any other time. Your system needs time to readjust back to normal digestion and assimilation. Not taking the proper measures can result in stomach cramping, nausea, and even vomiting.
The adjustment period necessary is based on the length of the fast. Four days is considered adequate for any of the longer fasts, 1-3 days for shorter fasts, and just a day or so for one-day fasts.
The most nutritious and easy-to-digest foods are used to break a fast initially, gradually adding more diversity and complexity over time.
The type of fast employed will determine the type of foods you use to break it. While juice or fruit are good for breaking a water fast, obviously, they aren't very helpful in breaking juice or fruit fasts.
To help you determine when to introduce the different food groups, use the following list. It begins with those that are easiest on the system and can be introduced early on, and progresses to those that should be added later.
Depending on the length of your fast, you may go through the list in one day or in 4 days. And you certainly don't need to eat everything on the list, it's just a general guideline.
fruit and vegetable juices
vegetable or bone broths
yogurt (or other living, cultured milk products), unsweetened
lettuces and spinach (can use plain yogurt as a dressing and top with fresh fruit)
cooked vegetables and vegetable soups
well cooked grains and beans
nuts and eggs
milk products (non-cultured)
meats and anything else
Any of the first three items are good for that initial "breaking" of a fast, that first thing you eat; raw fruit being the easiest and most popular.
According to this article by Dr. Michael M. Segal MD PhD:
Even people who have prepared well for fasting will be hungry after Neila. Be sure not to eat food too quickly at the post-fast meal. Begin the break-fast meal with several glasses of fluid: these counteract the dehydration and occupy space in the stomach, discouraging you from eating too rapidly. Also be careful about eating high salt foods such as lox, since you will still be a little dehydrated and will need to drink a lot of fluids to avoid waking up extremely thirsty in the early morning hours. Expect to drink as much fluid in the post-fast evening as you drink in a regular day.
I know a family that breaks its fast on coffee and dry cereal. Some of them also have light cake (like sponge cake, not a brownie or anything with cream) or orange juice. This kind of food is chosen specifically because of the considerations mentioned in the question: that heavier food would make them sick.
That said, I have no reason to think it's the best way to break a fast, which is what the question asks for.