Second Night Effect
The most difficult phase of a fast, marked by poor sleep and strong cravings.
This phase often appears during longer fasts and can feel uncomfortable. Sleep may be lighter and hunger signals can feel stronger than usual. It is a temporary response as the body adjusts to a deeper fasting state. Understanding this helps you avoid breaking the fast too early out of frustration.
Related Topics
Related glossary terms
Action Loop
Repeating fasting, calorie control, and walking as the core routine.
Eating Window
A defined time period when food is consumed.
Fasting Arc
The predictable progression of physical and mental states during a fast.
Fasting Window
The period where no calories are consumed.
Fat-adapted State
A state where the body relies more on fat than carbohydrates for energy.
Fat-Burning Switch
The point where fat becomes the primary fuel source after glycogen depletion.
Metabolic Switch
The transition from burning carbs to burning fat.
Momentum Window
The period after a fast where fat burning remains elevated and hunger is reduced.