Intermittent Fasting Planner
Plan your eating and fasting windows based on your wake-up time
Intermittent Fasting: What It Does, What It Doesn't
Intermittent fasting (IF) is an eating pattern — not a diet. It restricts when you eat, not necessarily what. The research is clearer than the internet makes it sound: IF works for fat loss primarily because it reduces overall calorie intake, not because of any unique metabolic magic.
The most common protocols are 16:8 (fast 16 hours, eat in an 8-hour window), 18:6, 20:4, and OMAD (one meal a day). Extended fasts of 24-72 hours exist but aren't daily practice for most people. A 2020 randomized trial (Lowe et al.) found 16:8 produced similar fat loss to continuous calorie restriction — not better, not worse. The meta-analysis by Welton et al. (2020) reached the same conclusion: IF is as effective as traditional dieting for weight loss, with some adherence advantages for people who prefer structure.
What IF does well: reduces calorie intake by compressing eating windows, improves insulin sensitivity in some populations, simplifies meal planning (fewer meals = fewer decisions), and may improve cognitive focus during fasted hours. What IF doesn't do: trigger special metabolic pathways unavailable via other means, melt fat faster than equivalent calorie deficits, or compensate for overeating during the eating window. A 3,000-calorie binge at 2pm is still 3,000 calories even if you didn't eat before noon.
Electrolytes matter during fasts longer than 16 hours. Sodium (1000-2000mg), potassium (200-300mg), and magnesium (100mg) help prevent the headaches, lightheadedness, and fatigue that make many people think fasting 'doesn't work for them.' Women should be cautious with extended fasts — research suggests longer protocols (20:4, OMAD) may disrupt menstrual cycles and stress hormones more readily in women than men. Start with 14:10 or 16:8 before pushing longer.
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Intermittent Fasting FAQ
Intermittent fasting (IF) is an eating pattern that cycles between periods of eating and fasting. It does not specify which foods to eat, but rather when you eat them. Popular methods include 16:8 (16 hours fasting, 8-hour eating window), 20:4, and 5:2 (two low-calorie days per week).
IF can help with fat loss primarily by making it easier to maintain a calorie deficit — eating in a shorter window often means eating fewer total calories. Research shows IF is equally effective as traditional calorie restriction when total calories are matched. The best approach is whichever you can sustain long-term.
Yes. Light to moderate exercise during a fast is generally safe. For intense resistance training, eating before or shortly after your workout is recommended to fuel performance and recovery. Many people train at the end of their fasting window and break their fast with a post-workout meal.
Water, black coffee, and plain tea are generally considered acceptable during fasting periods as they contain negligible calories. Anything with significant calories — including milk, sugar, juice, or supplements with calories — will break a fast.