What Time Does Fasting Begin and End? A Guide to Religious and Health Fasting

October 27, 2025 •

4 min read

According to a study cited by Johns Hopkins Medicine, after hours without food, the body exhausts its sugar stores and begins burning fat, a process known as metabolic switching. Understanding what time does fasting begin and end is the foundational principle for anyone embarking on this practice, whether for spiritual discipline or health and wellness.

Quick Summary

This article explores the starting and ending times for various types of fasting, including religious observances like Ramadan and popular health methods such as intermittent fasting. It covers how factors like location and method influence the schedule, and offers practical tips for managing your fast safely and effectively.

Key Points

Religious Timing: In Islam, fasting begins before the pre-dawn Fajr prayer and ends at sunset with the Maghrib prayer, with exact times varying by location and time of year.
Intermittent Fasting Windows: Common health-based intermittent fasting schedules include the 16:8 method (16 hours fasting, 8 hours eating) and the 14:10 method.
Location's Impact: A person's geographical location significantly affects the duration of religious fasting, with longer days in the summer for those farther from the equator.
Start Smart: For both health and religious fasting, a pre-fast meal rich in complex carbs, protein, and healthy fats is recommended for sustained energy.
Break Gently: To avoid discomfort, break your fast with small, easily digestible foods before consuming a larger meal.
Safety First: Consult a healthcare professional before starting any fasting regimen, especially if you have underlying medical conditions.
Stay Hydrated: Always prioritize hydration, especially during fasting periods where water intake is permitted.

Religious Fasting: Times Determined by the Sun

For followers of Islam, fasting during the holy month of Ramadan is a practice of abstaining from food, drink, and other physical needs from dawn until dusk. The exact times are determined by local sunrise and sunset, which is why fasting durations vary significantly depending on geographical location and the time of year. The beginning of the fast each day, known as suhoor, must be completed before the pre-dawn call to prayer (Fajr). The fast is broken at dusk with a meal called iftar, which follows the sunset call to prayer (Maghrib). This schedule ensures that fasting hours are consistent within a given region on a particular day, but not across the globe. For example, a Muslim in Norway will fast for much longer in the summer than one near the equator.

How to Determine Religious Fasting Times

Calculating the precise start and end times for religious fasting relies on astronomical observations and local prayer timetables. Tools like online Ramadan calendars and mobile apps provide accurate, localized timings for Fajr and Maghrib prayers, which dictate the fast.

Fasting begins: Before the Fajr (pre-dawn) prayer, when the first light of dawn becomes distinct from the darkness of night.
Fasting ends: At the time of the Maghrib (sunset) prayer, when the sun's disk disappears below the horizon.
Travelers' rules: A traveler moving across time zones should observe the fast according to the local times of their current location.

Health-Based Fasting: Setting Your Own Schedule

For those who practice intermittent fasting (IF) for health benefits, the start and end times are not tied to celestial events but are self-selected based on a preferred schedule. The most common approach, time-restricted eating, involves setting a daily eating window and a fasting window. This offers flexibility to adapt the fasting period to an individual's lifestyle and circadian rhythm.

Common Intermittent Fasting Schedules

16:8 Method: Fast for 16 hours, eat during an 8-hour window. For example, eating between 12 p.m. and 8 p.m..
14:10 Method: A more gentle introduction to IF, with a 14-hour fast and a 10-hour eating window.
20:4 Method (Warrior Diet): Fast for 20 hours and eat all daily calories within a 4-hour window, typically in the evening.
Alternate-Day Fasting: Involves alternating between days of normal eating and days of significant calorie restriction (or full fasting).

Comparison of Fasting Methods


Feature	Religious Fasting (e.g., Ramadan)	Intermittent Fasting (IF)	Extended Fasting
Driving Factor	Spiritual devotion, obedience to religious scripture	Health benefits like weight loss, metabolic health	Therapeutic or spiritual purposes under medical supervision
Start & End Times	Predetermined by astronomical events (dawn to dusk); varies daily with season and location	Self-selected daily or weekly windows; consistent and based on personal schedule	Duration is predefined (e.g., 24-72+ hours); not a daily cycle
What is restricted?	Food, drink, and other physical needs	Calories (food and caloric beverages); water is usually allowed	All calories; water is usually allowed
Flexibility	Less flexible; fixed times according to religious tenets	Highly flexible; can be adjusted to fit lifestyle	Requires careful planning and medical oversight due to longer duration
Safety Precautions	Exemptions for the sick, elderly, pregnant, or traveling; pre-dawn and post-dusk meals are important for hydration and nutrition	Not for everyone (e.g., pregnant/breastfeeding women, those with eating disorders or type 1 diabetes); consult a doctor before starting	Can be dangerous; must be done under strict medical supervision

Preparing for and Maintaining a Fasting Schedule

Regardless of the type of fast, preparation is key to a safe and successful experience. For intermittent or extended fasts, planning your nutrient intake is critical to avoid deficiencies. For religious fasts, which may involve longer hours and no water, staying hydrated during non-fasting hours is paramount. A pre-fast meal rich in complex carbohydrates, lean protein, and healthy fats can provide sustained energy and make the fasting period more manageable.

Stay hydrated: Drink plenty of water and calorie-free fluids during your eating window or non-fasting hours.
Fuel wisely: The pre-fast meal should be nutrient-dense to help maintain stable blood sugar levels and energy.
Listen to your body: Pay attention to hunger signals, energy levels, and any adverse symptoms. Adjust your schedule or seek medical advice as needed.
Consider gradual adaptation: If starting a new fasting routine, ease into it gradually to allow your body to adapt.
Be mindful when breaking a fast: End your fast with smaller, easily digestible foods rather than a large, high-carb meal to avoid discomfort.

Conclusion

While the answer to "what time does fasting begin and end?" varies significantly based on purpose and method, the underlying principles of careful timing and thoughtful preparation are universal. For religious observance, the schedule is fixed and aligned with solar events, demanding consistency and spiritual focus. For health-driven intermittent fasting, the timing is a tool to be customized for metabolic health and weight management. By understanding the specific requirements of your chosen fasting method and taking the necessary health precautions, you can ensure a safe and successful fasting experience that aligns with your personal goals. For more on the health science behind fasting, Johns Hopkins Medicine offers extensive resources on the benefits and considerations.

Frequently Asked Questions

No, intermittent fasting (IF) follows a schedule chosen for health purposes, such as a 16-hour fast and 8-hour eating window, whereas religious fasting, like in Ramadan, follows strict, dawn-to-dusk timings set by scripture and local celestial events.

For intermittent fasting, any caloric intake technically breaks a fast. While some debate exists on small amounts, it is generally advised to stick to zero-calorie beverages like water, black coffee, or plain tea during the fasting window.

The fasting times for Ramadan are based on local sunrise and sunset. You can find accurate, up-to-date schedules for your specific location using online resources, mobile apps, or consulting local mosques.

Fasting is not suitable for everyone. Individuals who are pregnant, breastfeeding, under 18, have a history of eating disorders, or certain health conditions like Type 1 diabetes should avoid fasting unless under the supervision of a doctor.

Before a fast, a meal high in fiber, healthy fats, and protein helps provide sustained energy. When breaking a fast, start with easily digestible foods to ease your digestive system back into eating, and rehydrate properly.

Geographical location has a significant impact on religious fasting times, as they are determined by daylight hours. Muslims in northern latitudes experience much longer fasts during summer compared to those closer to the equator.

Metabolic switching is the process where the body, after using its glucose stores, begins to burn fat for energy. This is a key benefit often associated with intermittent fasting.

Yes, it is often recommended to listen to your body and potentially reduce the intensity of workouts while fasting. Ensuring proper hydration and timing exercise with your eating window is also important.