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Intermittent Fasting Window Planner

Your eating window, fasting times, and optimal wake-up schedule.

📅 Updated April 2026 ✅ Formula verified 📖 4 min read 🆓 Free · No sign-up

Benefits of intermittent fasting

Research supports IF for weight loss, insulin sensitivity improvement, and potential longevity benefits via autophagy (cellular cleanup) that activates after ~14–16 hours of fasting.

Choosing your protocol

  • 16:8: Most sustainable, great starting point
  • 18:6: Better weight loss, harder to maintain socially
  • OMAD: Most aggressive, requires careful nutrition planning
  • 5:2: Two 500-calorie days/week — good for social eaters
⚡ CalcWolf Insight

A 2019 New England Journal of Medicine review found intermittent fasting improved oxidative stress markers independent of weight loss.

Frequently asked questions
When does fat burning start during fasting?▾
Glycogen depletion begins around 12–14 hours. Ketone production (fat burning) increases significantly after 16+ hours. Maximum autophagy: 18–24+ hours.
Is intermittent fasting safe for everyone?▾
IF is not recommended for pregnant or breastfeeding women, people with a history of eating disorders, type 1 diabetics, children and teenagers, or people taking medications that require food. Consult a doctor before starting if you have any chronic health condition.
✓ Math logic verified against primary sources → See our verification process
Kevin Glover
Founder, CalcWolf · GLVTS · Blickr
All formulas sourced from primary references — IRS publications, peer-reviewed research, and official standards. Results are tested against independent reference calculators before publishing. Rates and brackets updated when official sources change. Editorial policy →

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