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Intermittent Fasting Calculator — Fasting Window Planner
Plan and structure your intermittent fasting schedule (16:8, 14:10, 18:6, or 20:4) based on your daily timeline and lifestyle.
What is Intermittent Fasting?
Intermittent fasting (IF) is an eating pattern that cycles between periods of fasting and eating. Rather than restricting *what* you eat, it focuses on structuring *when* you eat.
Popular Fasting Protocols
- 16:8 (Leangains): A popular schedule featuring a 16-hour fasting window and an 8-hour eating window (e.g., eating between 12 PM and 8 PM).
- 14:10: A gentler schedule suitable for beginners, with a 14-hour fast and 10-hour eating window.
- 18:6: A more advanced protocol featuring an 18-hour fast and a 6-hour eating window.
- 20:4 (Warrior Diet): An advanced fast featuring a 20-hour window and a single 4-hour evening meal.
The Biology of Fasting
Fasting triggers metabolic shifts. After about 12 hours of fasting, glycogen stores in the liver begin to deplete, prompting the body to transition toward burning fatty acids for energy—a metabolic state sometimes called the 'keto switch.'
Frequently Asked Questions
Aim for zero-calorie fluids: water, black coffee, and unsweetened tea. Avoid sugar, milk, and cream, as they break the fast by raising insulin levels.
When combined with adequate protein intake and resistance training, intermittent fasting can help preserve muscle mass while promoting fat loss.
Intermittent fasting is not recommended for pregnant or breastfeeding women, individuals with a history of eating disorders, or those under 18 years old.