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Find your ideal intermittent fasting window based on your schedule, goals, and preferred protocol. Our IF calculator generates your exact eating and fasting times, calorie targets, and tips for starting and sticking to your fasting plan.

Cara menggunakan kalkulator ini

  1. Masukkan Fasting Protocol
  2. Masukkan Wake-Up Time
  3. Masukkan Preferred First Meal Time
  4. Klik butang Kira
  5. Baca keputusan yang dipaparkan di bawah kalkulator

What Is Intermittent Fasting?

Intermittent fasting (IF) is an eating pattern that cycles between periods of fasting and eating. It doesn't specify which foods to eat — only when to eat them. IF is not a diet in the traditional sense; it's an eating schedule that can be applied to any dietary approach.

During fasting periods, insulin levels drop, enabling fat burning. After 12–16 hours of fasting, glycogen stores are partially depleted and the body increasingly mobilizes stored fat for energy. Longer fasts (18–24+ hours) trigger autophagy — the cellular cleanup process associated with longevity and disease prevention.

The key insight: many people naturally eat in a compressed window when they skip breakfast or eat an early dinner — IF simply makes this intentional and consistent.

Popular IF Protocols Compared

ProtocolFast DurationEating WindowDifficultyBest For
16:816 hours8 hoursEasyBeginners, weight loss, maintenance
18:618 hours6 hoursModerateEnhanced fat loss, metabolic health
20:4 (Warrior)20 hours4 hoursHardAggressive fat loss, experienced fasters
OMAD23 hours1 hourVery HardMaximum calorie control
5:22 days at 500 cal5 normal daysModerateThose who prefer daily eating
Alternate DayEvery other dayEvery other dayHardSignificant weight loss

Benefits of Intermittent Fasting

Research supports multiple benefits of IF beyond simple caloric restriction:

What Can You Consume During the Fasting Window?

A true fast means zero calories. However, these are generally accepted as "fasting-safe":

For metabolic benefits (autophagy, fat burning), keep calories to zero. For pure weight loss through calorie restriction, small amounts of low-calorie items likely have minimal impact on results.

Intermittent Fasting and Exercise

Fasted exercise (training during the fasting window) is a controversial but common practice:

Fasted cardio advantages: Some research shows enhanced fat oxidation during fasted aerobic exercise. Subjectively, many people feel alert and energized training before breaking the fast.

Fasted cardio disadvantages: Performance (especially high-intensity work) may be reduced without carbohydrates. Risk of muscle breakdown is higher in very long fasted states. Post-exercise protein becomes more critical.

Practical recommendation: Endurance runners can train fasted for easy-to-moderate efforts (Zone 1–2). For intervals, tempo runs, or strength training, consider training within your eating window or having a small protein source beforehand.

If you must train in a fasted state for hard sessions, 20–40g of essential amino acids or BCAAs (which minimally impact fasting) can reduce muscle catabolism without significantly breaking the fast.

Who Should Be Cautious With IF

Intermittent fasting is safe for most healthy adults but requires caution or medical supervision for:

Common side effects when starting IF: hunger, headaches, irritability, and difficulty concentrating — typically resolve within 1–2 weeks as the body adapts to the new eating pattern.

Breaking the Fast: What to Eat

The first meal (breaking the fast) is often the most important. Recommendations:

Good first-meal options: Greek yogurt with berries, eggs and vegetables, protein smoothie, chicken salad — high protein, moderate carbs, plenty of fiber.

Kemas kini terakhir: March 2026

Frequently Asked Questions

What is the best intermittent fasting schedule for beginners?

16:8 is ideal for beginners. Start by simply delaying breakfast by 2–4 hours and stopping eating 2–3 hours before bed. For example: eat from 12pm–8pm, fast from 8pm–12pm. This is easy to maintain and allows a social dinner window.

Can I drink coffee while intermittent fasting?

Yes, black coffee is generally accepted during fasting periods. It contains minimal calories, may suppress appetite, and some research suggests coffee enhances autophagy. Adding milk, cream, or sugar breaks the fast.

How long does it take to see results with IF?

Many people notice reduced hunger and better energy within 1–2 weeks as the body adapts. Weight loss typically becomes visible after 2–4 weeks. Metabolic health improvements (insulin sensitivity, blood sugar) may take 4–8 weeks.

Will intermittent fasting slow my metabolism?

Short-term IF (less than 72 hours) does not slow metabolism. Some studies show 24-hour fasts actually increase metabolic rate by 3.6–14% due to elevated norepinephrine. Prolonged severe caloric restriction (not IF) does suppress metabolism over time.

Can I do IF while building muscle?

Yes, but it requires adequate protein and calories within your eating window. Studies show similar muscle gain with IF vs. regular eating when protein and calories are matched. Ensure you hit your daily protein target (1.6–2.2g/kg) within your eating window.

Is OMAD (one meal a day) healthy?

OMAD can work for weight loss but is challenging to meet nutritional needs (protein, fiber, micronutrients) in one sitting. Most people struggle to eat enough calories and may lose muscle mass. 16:8 or 18:6 are more sustainable and nutritionally complete for most people.

Does IF break down muscle?

Short fasting periods (16–18 hours) do not significantly break down muscle, especially with adequate daily protein. Very long fasts (48+ hours) begin to mobilize muscle protein. For muscle preservation, stay within 16–20 hours and prioritize protein at your first meal.

What is autophagy and when does it start?

Autophagy is the cellular self-cleaning process where cells recycle damaged components. It typically begins around 12–16 hours into a fast and increases significantly after 24 hours. Regular 16:8 fasting provides modest autophagy benefits.

Can I exercise during my fasting window?

Yes. Many people perform fasted exercise without issues, especially for low-to-moderate intensity work. High-intensity training (intervals, heavy lifting) may suffer without carbohydrates. Experiment with both approaches to see what works for your performance and recovery.

How do I stop feeling hungry during fasting?

Hunger during IF is mainly habitual. Tips: Stay hydrated (water and black coffee/tea suppress appetite), consume adequate protein and fiber during eating windows, start with a shorter fast (12–14 hours) and gradually extend, keep busy during fasting periods, and use salt/electrolytes if dizzy or headachy.