24-Hour Fasts A twenty-four-hour fast involves fasting from dinner to dinner, or breakfast to breakfast, whatever you prefer. For example, if you finish dinner at 7 p.m. on day 1, you would then fast until having dinner at 7 p.m. on day 2. Despite the name, you do not actually go a full day without eating, since you are still taking one meal on the fasting day. In essence, you are eating a single meal for that day.
