Intermittent Fasting Timer
Track your fasting window and see what metabolic stage you're in. Perfect for 16:8, 18:6, 20:4, OMAD, and custom fasting schedules.
How to Use the Fasting Timer
- Choose Protocol: Select your fasting schedule (16:8, 18:6, 20:4, OMAD, or custom)
- Set Start Time: When did you start fasting? (Use "Start Now" or enter specific time)
- Track Progress: Watch your fasting timer and see which metabolic stage you're in
- Complete Fast: Timer shows when you've reached your goal and can break your fast
Understanding Fasting Stages
Stage 1: Fed State (0-4 hours)
What's Happening: Your body is digesting food and absorbing nutrients. Insulin levels are elevated, and glucose is the primary fuel source.
Benefits: None yet—this is your normal post-meal state.
Stage 2: Early Fasting (4-12 hours)
What's Happening: Blood sugar and insulin levels drop. Your body starts depleting glycogen stores (stored carbohydrates) in the liver and muscles.
Benefits: Insulin sensitivity begins improving. This is the beginning of metabolic switching.
Stage 3: Fat Burning (12-16 hours)
What's Happening: Glycogen stores are significantly depleted. Your body ramps up fat burning and begins producing ketones as an alternative fuel source.
Benefits: Increased fat oxidation, ketone production starts, improved mental clarity for many people.
Stage 4: Ketosis (16-24 hours)
What's Happening: Deep ketosis sets in. Your brain is now running primarily on ketones. Fat burning is maximized. Growth hormone levels increase.
Benefits: Maximum fat burning, mental clarity, reduced inflammation, improved energy for many.
Stage 5: Autophagy (24+ hours)
What's Happening: Autophagy (cellular "self-eating") significantly increases. Your body breaks down old, damaged proteins and cellular components for recycling and energy.
Benefits: Cellular repair, longevity benefits, immune system reset, enhanced autophagy.
Popular Fasting Protocols
16:8 Method
Fast: 16 hours | Eat: 8 hours
Most popular and sustainable. Skip breakfast, eat from noon-8pm (or your preferred 8-hour window).
Best for: Beginners, lifestyle integration
18:6 Method
Fast: 18 hours | Eat: 6 hours
Slightly more aggressive. Eating window: 1pm-7pm or 2pm-8pm.
Best for: Intermediate fasters, weight loss
20:4 (Warrior Diet)
Fast: 20 hours | Eat: 4 hours
One large meal plus light snacking. Very restrictive eating window.
Best for: Advanced fasters, aggressive fat loss
OMAD (23:1)
Fast: 23 hours | Eat: 1 hour
One meal a day. Maximum autophagy and fat burning benefits.
Best for: Experienced fasters, maximum benefits
5:2 Diet
Eat normally 5 days, restrict to 500-600 calories on 2 non-consecutive days.
Best for: Those who prefer weekly structure
Alternate Day Fasting
Fast every other day (or eat very lightly). Eat normally on non-fast days.
Best for: Aggressive results, experienced fasters
Frequently Asked Questions
Does coffee break my fast?
Black coffee: No, does not break fast. With cream/sugar: Yes, breaks fast (stimulates insulin). With MCT oil/butter (bulletproof): Technically breaks fast but may maintain some benefits. For strict fasting, stick to black coffee, tea, or water only.
Can I exercise while fasting?
Yes! Fasted cardio and strength training are fine for most people. Your body can perform well on ketones and stored fat. Start light if new to fasted exercise. Intense workouts near the end of long fasts may be challenging—listen to your body.
Will I lose muscle while fasting?
No, if done correctly. Studies show intermittent fasting (especially 16:8 to 20:4) preserves muscle mass well. Keys: (1) Eat adequate protein during eating window (0.8-1g per lb bodyweight), (2) Continue strength training, (3) Don't fast excessively long without proper nutrition.
I feel tired/dizzy during fasting. Is this normal?
Common when starting. Often due to: (1) Low electrolytes (add salt, magnesium, potassium), (2) Dehydration (drink more water), (3) Adaptation period (takes 1-2 weeks). If symptoms persist, consult a doctor or reduce fasting duration.
How long should I fast for autophagy?
Autophagy begins around 16-18 hours and ramps up significantly at 24+ hours. For regular autophagy benefits, 18-24 hour fasts 1-2x per week are effective. Extended fasts (48-72 hours) provide maximum autophagy but should be done carefully with medical supervision.
What can I have during fasting that won't break my fast?
Safe: Water, black coffee, unsweetened tea, sparkling water, salt/electrolytes. Breaks fast: Anything with calories (cream, sugar, protein, fats), artificial sweeteners (debatable—may spike insulin in some people), bone broth (has calories but minimal insulin response).
Should I fast every day?
16:8 daily is safe and sustainable for most people. More aggressive protocols (20:4, OMAD) can be done daily but listen to your body. It's also fine to fast 5-6 days per week and eat normally on weekends. Consistency matters more than perfection.
🌟 Fasting Tips for Success
- Start Slow: Begin with 12:12, then progress to 14:10, then 16:8. Don't jump straight to OMAD.
- Stay Hydrated: Drink 2-3 liters of water daily. Add electrolytes if fasting 18+ hours.
- Keep Busy: Distraction helps. Many report fasting is easier on busy workdays.
- Break Fast Gently: Don't binge after fasting. Start with something light (protein, vegetables).
- Track Progress: Take measurements, not just weight. You're building metabolic flexibility.
- Sleep Counts: 8 hours of sleep = 8 hours of effortless fasting. Go to bed slightly hungry.
Who Should NOT Do Intermittent Fasting
Avoid IF if you: Are pregnant or breastfeeding, have a history of eating disorders, are underweight (BMI < 18.5), have type 1 diabetes, are under 18 years old, or have certain medical conditions.
Consult a doctor first if you: Have type 2 diabetes or take medications, have low blood pressure, have a history of amenorrhea, are taking prescription medications, or have any chronic health conditions.
Remember: Fasting is a tool, not a religion. If it doesn't feel right for your body or lifestyle, that's perfectly fine. There are many paths to health.
Intermittent fasting is not suitable for everyone. Consult with a healthcare provider before starting any fasting regimen, especially if you have diabetes, low blood pressure, take medications, are pregnant/breastfeeding, have a history of eating disorders, or have any medical conditions. This tool is for informational and tracking purposes only and should not replace professional medical advice.