Intermittent fasting (IF) is one of the most researched dietary strategies of the past decade. Unlike specific diets, IF is an eating pattern — when you eat, not what you eat. Use our intermittent fasting calculator to plan your eating window, and this guide to choose the right protocol.
The Main Intermittent Fasting Protocols
| Protocol | Eating Window | Fast Length | Best For |
|---|---|---|---|
| 14:10 | 10 hours | 14 hours | Beginners — easy to maintain |
| 16:8 | 8 hours | 16 hours | Most popular — proven results |
| 18:6 | 6 hours | 18 hours | Intermediate — stronger calorie restriction |
| 20:4 (Warrior) | 4 hours | 20 hours | Advanced — one main meal + snacks |
| OMAD | 1 hour | 23 hours | Advanced — one meal per day |
| 5:2 | Normal 5 days | 2 fast days/wk | Those who prefer weekly structure |
Choosing the Right Protocol for You
Consider Your Schedule
16:8 with a noon-8pm eating window is the most common — skip breakfast, eat lunch and dinner normally. If your work requires early morning focus, consider an earlier window (9am-5pm). For social eaters, align your window with dinner and social events.
Consider Your Goals
For weight loss: 16:8 is well-researched and sustainable. For metabolic health or longevity benefits: 18:6 or periodic extended fasts show additional benefits beyond calorie restriction alone. For simplicity: 5:2 separates the fasting days from normal life, which some find easier psychologically.
What Breaks a Fast
Technically: anything that triggers an insulin response. Practically: anything with calories. Safe during fasting: water, black coffee, plain tea, plain sparkling water. May break a fast: milk in coffee, flavored drinks, supplements with calories, gum.
Tracking Results
Weight on a scale alone is unreliable for IF tracking — water weight fluctuates by 1-3kg daily. Better metrics: weekly average weight (not daily), waist circumference measurements, how clothes fit, energy levels, blood glucose if diabetic, and mental clarity reports.
Intermittent Fasting Tracker and Health Planner
Daily IF schedule planner, weekly weight tracking, and 30-day progress journal. Pre-built to work with 16:8, 18:6, and 5:2 protocols.
Get the IF Tracker →Not recommended for: pregnant or breastfeeding women, people with a history of eating disorders, children and adolescents, those with type 1 diabetes or on insulin. Consult a doctor before starting if you have any medical condition, are underweight, or are on medication that requires food. For healthy adults, the research consistently shows IF is safe and often beneficial.
Most people see scale changes within 1-2 weeks (initial water weight loss from glycogen depletion, plus some actual fat). Meaningful fat loss: 4-8 weeks of consistent IF combined with reasonable overall calorie intake. Metabolic adaptations (improved insulin sensitivity, autophagy markers): 4+ weeks of consistent practice.