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One or two full 24-hour fasts per week. Maximum periodic calorie reduction.
Last updated: February 21, 2026
24h, 1-2x/week
Fasting Window
Normal other days
Eating Window
2,200
Est. Weekly Deficit (cal)
~0.63 lbs
Est. Loss per Week
The 24-hour fast involves completely abstaining from food for a full 24 hours, typically once or twice per week. It is sometimes called "Eat Stop Eat," after Brad Pilon's popular book. The protocol produces the largest single-session calorie deficit of any non-extreme fasting approach. On fasting days, you eat dinner one night and do not eat again until dinner the next night, completing a full 24-hour fast while still eating every day.
On your fasting day, finish dinner at 7pm. Do not eat anything until 7pm the following day. Drink water, black coffee, and plain tea throughout the fast. Break the fast with a normal-sized dinner. Do not compensate for the missed day by overeating. Stick to your regular TDEE on eating days. Start with one 24-hour fast per week before considering two. Most people find the 18-22 hour mark the hardest part of the fast.
| Day | Eating | Fasting |
|---|---|---|
| Monday | Normal eating (TDEE) | None |
| Tuesday | Dinner only (7:00pm) | Monday 7pm to Tuesday 7pm |
| Wednesday | Normal eating (TDEE) | None |
| Thursday | Normal eating (TDEE) | None |
| Friday | Dinner only (7:00pm) | Thursday 7pm to Friday 7pm |
| Saturday | Normal eating (TDEE) | None |
| Sunday | Normal eating (TDEE) | None |
Experienced fasters who have plateaued on weekly protocols like 5:2
People who can tolerate very high levels of hunger and discomfort for one day per week
Those who want maximum flexibility on eating days and can endure one hard day
Anyone with a history of disordered eating, people in demanding physical jobs or sports who cannot afford a full day of impaired performance, and anyone new to fasting. Work up to 24-hour fasts gradually.
Intermittent fasting controls when you eat. What you eat during the eating window still determines whether you lose fat, maintain muscle, or stall entirely. The most effective approach is scanning your meals with FitCommit as you eat, so you know your daily protein, calorie, and macro totals without logging every ingredient manually. Point your camera at your plate, and the AI identifies the meal and calculates the nutrition in seconds.
Tracking your eating window nutrition takes less than two minutes per day and eliminates the guesswork that causes most IF practitioners to either undereat protein (causing muscle loss) or overeat calories (negating the fast). The combination of a proven fasting schedule and accurate nutrition tracking produces results that neither approach achieves alone.
Track Your Eating Window with FitCommit24-Hour Fast is not suitable for pregnant or breastfeeding women, people with a history of eating disorders, those with Type 1 diabetes or insulin-dependent Type 2 diabetes, or anyone under 18. People on blood pressure or blood sugar medications should consult their doctor before starting any fasting protocol, as medication timing may need to be adjusted. If you experience persistent dizziness, extreme fatigue, or heart palpitations, stop the protocol and speak with a healthcare professional.
Calculate your TDEE (Total Daily Energy Expenditure) using a reliable calculator or app. Then eat 10 to 20 percent fewer calories during your eating window to create a calorie deficit. Do not try to eat your entire TDEE in a compressed window. For 24-Hour Fast, eating 200 to 500 calories below your TDEE on normal days is typically sufficient. FitCommit can calculate your exact TDEE based on lean mass from an AI body scan.
Prioritize protein first: lean meats, fish, eggs, Greek yogurt, cottage cheese, or legumes. Aim for 0.7 to 1.0 grams of protein per pound of bodyweight per day. Fill the rest of your calories with whole foods: vegetables, fruits, whole grains, and healthy fats. Avoid using the eating window as license to eat anything. 24-Hour Fast creates a calorie reduction primarily through time restriction, but food quality and quantity still determine your results.
Only attempt this after successfully maintaining a less aggressive protocol for at least four to six weeks. Adaptation takes time. During the fasting period, stay hydrated with water, black coffee, or plain tea. Track your eating window with a fasting app or phone timer so you know exactly when to start and stop eating. Most people find it easiest to schedule their fast to overlap with sleep.
Scan any meal in seconds. FitCommit's AI identifies your food from a photo and calculates macros instantly. Stop guessing what you ate during your eating window. Free 7-day trial.
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