Intermittent Fasting: The Framework
Not a diet. A schedule. Compress when you eat, naturally consume fewer calories, and let your body access stored fat.
Intermittent fasting (IF) isn't a diet. It's a schedule. You're not changing what you eat — you're changing when you eat. And by compressing your eating into a shorter window, you naturally consume fewer calories without having to obsessively count every one.
Popular IF Protocols
Fasting vs. Eating Windows
16:8 — Fast 16 hours, eat within 8 hours
The most common and easiest to start with. Skip breakfast, eat your first meal at noon, finish eating by 8 PM. You're already fasting 8 hours while sleeping — this just extends it.
Best for: Beginners, people with normal work schedules, those who aren't hungry in the morning anyway.
Expected calorie reduction: 200-400 cal/day naturally, without counting.
18:6 — Fast 18 hours, eat within 6 hours
A tighter eating window. Eat your first meal at 1 PM, finish by 7 PM. This naturally limits you to 2 meals with minimal snacking opportunity.
Best for: People comfortable with 16:8 looking for more structure. The sweet spot for many.
Expected calorie reduction: 400-600 cal/day naturally.
20:4 — Fast 20 hours, eat within 4 hours
Known as the "Warrior Diet" approach. One main meal and a small meal or snack within a 4-hour window. Significant calorie reduction happens naturally.
Best for: Experienced fasters, people who prefer larger meals, those who find counting calories tedious.
Expected calorie reduction: 500-800 cal/day naturally.
5:2 — Eat normally 5 days, restrict 2 days
Eat your normal maintenance calories 5 days per week. On 2 non-consecutive days, eat only 500–600 calories. This creates a significant weekly deficit without daily restriction.
Best for: People who hate daily restriction, social eaters, those who prefer "hard days and easy days."
Expected weekly deficit: 2,800-3,000 cal/week (from restricted days alone).
What Happens During a Fast
Your body goes through distinct metabolic phases during a fast:
The Fasting Timeline
Fed State
Body digests and absorbs food. Insulin high. Fat burning off.
Early Fasting
Insulin drops. Body starts using glycogen stores.
Glycogen Depletion
Glycogen running low. Body transitions to fat burning.
Fat Burning Zone
Primary fuel source: stored body fat. Growth hormone rises. Autophagy begins.
Deep Fasting
Significant fat oxidation. Cellular cleanup (autophagy) accelerates.
How to Start Without Failing
🎯 Start Small
Don't jump to 20:4 on day one. Start with 14:10 (skip breakfast, eat from 10 AM to 8 PM) and gradually tighten your window over 2–4 weeks. Your body adapts — hunger in the morning will fade within days.
- Week 1: 14:10. Skip breakfast. First meal at 10 AM, last meal by 8 PM. This is barely noticeable for most people.
- Week 2: 16:8. Push first meal to noon. Last meal by 8 PM. The classic IF window.
- Week 3-4: 18:6. First meal at 1 PM, last by 7 PM. Two meals, no snacks.
- Beyond (optional): 20:4 or OMAD. Only if you want more. 18:6 is perfectly effective for most people long-term.
What You Can Have During a Fast
- ✅ Water (unlimited — aim for 80+ oz/day)
- ✅ Black coffee (no sugar, no cream, no milk)
- ✅ Plain tea (green, black, herbal — nothing added)
- ✅ Sparkling/mineral water
- ✅ A pinch of salt if you feel lightheaded (electrolytes)
- ❌ Diet soda (artificial sweeteners may trigger insulin in some people)
- ❌ Bone broth (technically breaks a strict fast)
- ❌ Anything with calories — even "just 20 calories" resets the clock
Tools That Help
The Complete Guide to Fasting
Dr. Jason Fung's comprehensive IF manual. Covers the science, protocols, and practical tips from the world's leading fasting researcher.
Shop on Amazon →Electrolyte Supplement
Zero-calorie electrolytes prevent headaches and fatigue during longer fasts. Essential for 18+ hour fasts.
Shop on Amazon →Insulated Coffee Travel Mug
Your black coffee stays hot for hours. A good travel mug makes the morning fast enjoyable instead of endurable.
Shop on Amazon →Kitchen Timer
Set it when your eating window opens and again when it closes. Simple analog reinforcement of your boundaries.
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