How to Fast in Hour, Day, and Week-Long Intervals

Medically reviewed by Jenny Sweigard, MD

Before starting a fast, it's important to understand how to fast. With so many approaches—from intermittent to religious to water fasting—navigating your fasting journey can be overwhelming. Regardless of your reason for fasting, here are some things to consider before starting:

• Plan ahead

• Prepare your body

• Start gradually

• Stay active and occupied

• Choose filling food

• Listen to your body

This article elaborates on those considerations and discusses the basics of fasting, including how to fast for the first time, faith-based fasting, fasting for weight loss, and how long to fast. 

How to Fast for the First Time

Fasting, the deliberate abstinence from food and sometimes drink has been a cultural and religious practice for millennia. Regardless of your reason for fasting, it's essential to understand how to fast safely and effectively.

Embarking on your first fast can be a positive experience for your physical and mental well-being. Before beginning, talk to a healthcare provider to ensure your plan is a healthy and safe choice. Once you have the green light from a healthcare provider, consider these beginner-friendly fasting tips.

Plan Ahead

Start by making a plan that fits your lifestyle and goals before your fasting journey to ensure your fast is successful and effective. Popular fasting methods include:

• Time-restricted eating: This fasting plan involves consuming all your meals within a six--, eight-, or 10-hour window (e.g., 16:8 intermittent fasting), usually during your most active part of the day. For example, you may eat between 8:00 am and 6:00 pm and abstain from eating for the rest of the day and night.

• Circadian rhythm fasting: This involves adjusting your eating schedule with your body's natural circadian rhythm, opting for meals earlier in the day to align with your body's natural hormone fluctuations and sleep schedule.

• 5:2 method: The 5:2 method involves restricting your caloric intake to 500 to 600 calories on two non-consecutive days and eating normally for the remaining five days each week.

• Eat, stop, eat (24-hour): Similar to the 5:2 method, the eat, stop, eat fasting plan involves fasting for an entire 24-hour period once or twice per week, allowing for water and black coffee/tea on fasting days, then resuming normal eating after the fast.

• Alternate-day fasting: Fasting every other day (consuming only 25% of your body's daily caloric needs) and eating normally on non-fasting days.

Prepare Your Body

Preparing your body for fasting is one of the best ways to ensure your fast goes smoothly and you maintain energy levels during fasting hours and days. In the days leading up to your fast, focus on:

• Hydration: Drink at least eight glasses of water daily to prevent dehydration and keep your body's circulatory and lymphatic systems functioning.

• Nutritious foods: Eat nutrient-dense foods in the days leading up to your fast. Aim to eat breakfast, lunch, dinner, and two snacks with plenty of vegetables, fruits, lean proteins, and whole grains.

• Limiting processed foods: While you may feel tempted to eat your favorite treats or high-calorie foods before beginning your fast, it's best to avoid high-calorie meals or processed foods in the days leading up to your fast.

• Limiting calorie-dense beverages: Limit your alcohol intake to one glass of wine daily and avoid sodas (soft drinks) and other beverages with added sugars to avoid blood sugar spikes.

Start Gradually

If you're new to fasting, starting with a shorter-duration fast or a less restrictive method can help your body gradually adjust to your new eating schedule. As you become more accustomed to fasting, consider lengthening the time of the fast. 

It is helpful to schedule your fast around your natural rhythms. If you're an early riser, consider starting your eating window in the morning and beginning your fast in the evening. 

Stay Active and Occupied

Depending on your chosen fasting method, you may be asleep during many fasting hours. During your waking fasting hours, try to keep your mind occupied with activities you enjoy, like reading, going for a nature walk, or engaging in relaxation techniques such as yoga, meditation, or tai chi.

Meditation and mindfulness practices also help manage cravings and promote a sense of inner calm. Light exercise, such as walking, cycling, swimming, or hiking, may enhance your metabolism and boost your mood.

Choose Filling Foods

Opt for foods rich in protein, fiber, and healthy fats during your eating windows to help increase feelings of satiety (fullness) and help reduce feelings of hunger during your fasting hours. Nutrient-rich foods that enhance satiety include:

• Whole grains, such as oats, barley, and millet.

• Nuts and seeds, such as almonds, walnuts, and chia seeds.

• Legumes, such as beans and peas.

• Lean proteins, including low-fat dairy, seafood, and chicken breasts.

Listen to Your Body

Pay attention to your hunger and energy levels when fasting, and don't push yourself too hard. If you experience dizziness, fatigue, or intense hunger, consider breaking your fast and adjusting your approach. It's better to stay safe and healthy than to remain committed to a plan that is not working for you.

How to Practice Faith-Based Fasting

Many religions and spiritual traditions integrate fasting into their rituals, using it as a tool for introspection, spiritual growth, and connection with the community and the divine. Many faiths have unique fasting practices and purposes, including:

• Buddhism: Periodic fasting or abstaining from certain foods or fasting after midday each day is a common Buddhist practice to help cultivate mindfulness.

• Christianity: Lent, 40 days of reflection leading to Easter, often involves fasting on Ash Wednesday and Good Friday to connect with Jesus' suffering, repent, and discipline the body and mind.

• Hinduism: Fasting is a common Hindu practice to honor deities and encourage inner strength. For example, Ekadashi, observed twice a month, involves fasting to promote psychological well-being.

• Islam: The Islamic rule calls for a month-long fast from sun up to sun down during Ramadan, a month of prayer and reflection.

• Judaism: Yom Kippur, the Day of Atonement, calls for a 25-hour fast, emphasizing repentance and self-reflection.

No matter which faith you follow, these tips may help make your faith-based fast a success:

• Seek guidance: Consult your religious leader or spiritual advisor for specific guidelines and traditions within your faith, and discuss your fasting plan with your healthcare provider before starting.

• Stay hydrated: If your faith fasting practices allow it, drink plenty of water to prevent dehydration.

• Know your limits: Be mindful of your limitations and avoid pushing yourself to the point of harming your health. Listen to your body and break your fast or adjust your fasting plan as needed.

• Integrate with spiritual practices: Weave your fasting experience into your regular spiritual practices, such as prayer, meditation, or studying scripture.

How to Fast With Weight Loss Goals

Intermittent fasting has become popular in recent years as a potential tool for weight loss. Research shows fasting promotes weight loss in several ways:

• Fat burning: After eating, the body uses glucose (sugar) from food as an energy source. When glucose stores are depleted during fasting, the body begins to burn fat stores for energy.

• Caloric deficit: By limiting your eating window or skipping meals, you consume fewer calories than your body needs, leading to a caloric deficit and subsequent weight loss.

• Hormonal changes: Fasting may influence hormones related to hunger (ghrelin) and satiety (leptin), potentially leading to reduced hunger and increased feelings of fullness.

Choosing a method that fits your lifestyle, goals, and preferences is important for long-term weight management. Some of the most effective fasting methods for weight loss include:

• Alternate-day fasting (ADF): Research suggests that alternating between days of regular eating and days of significant calorie restriction (25% of the body's daily caloric needs) may reduce body weight between 3% and 7% within two to three months. ADF also improves cholesterol, blood pressure, and insulin sensitivity.

• Time-restricted eating (TRE): Studies show that adults who follow a TRE fasting plan—limiting the daily eating window into a specific timeframe (e.g., 8 hours) and fasting for the remaining hours—lose 1% to 4% of their body weight within several weeks.

• 5:2 fasting: Consuming a regular diet five days/week and limiting calorie intake two days a week (~500 calories/day) may lead to significant weight loss. A study exploring the effects of the 5:2 fast on body weight found that most participants lost more than 5% of their body weight, and nearly half lost more than 10% within 12 weeks.

Tips for fasting for weight loss include:

• Exercise: Fasting may help you lose weight, but it's not a magic bullet. Regular exercise in your daily routine promotes weight loss, builds strength, and supports your overall health.

• Focus on nutrition: Prioritize eating a nutritious, balanced diet to ensure your body gets the nutrients it needs (e.g., vitamins, minerals, fats, fibers).

• Stay hydrated: Drinking plenty of water is essential while fasting. You can also enjoy unsweetened black coffee or herbal teas.

• Talk to a healthcare provider: Ask whether fasting is right for you; a healthcare provider can guide and support your weight loss journey.

Fasting Side Effects & Special Considerations

While fasting has potential health benefits, some people experience side effects, such as:

• Dizziness

• Nausea

• Insomnia

• Headaches

• Weakness

• Hypoglycemia (low blood sugar)

• Mood swings
  

Fasting is not safe for everyone and is generally not recommended for:

• Children and teens

• Pregnant or lactating people

• Older adults

• People with certain underlying conditions (e.g., kidney disease, heart disease, diabetes)
  

How Long to Fast

There is no "one size fits all" approach to fasting, and how long you fast will depend on your goals, fasting experience level, and overall health.

Generally, beginners should start slowly and with time-restricted eating (e.g., 12-hour fasts) before considering longer durations. Experienced fasters can try longer-duration fasts, such as intermittent fasting 16:8 or alternate-day fasting. No matter your experience level, it's important not to fast for too many consecutive days, which can harm your health or cause your body to enter "starvation" mode and store fat.

Determining which fasting method is best for you may take some time. Consider trying different fasting cycles or alternating periods of fasting with regular eating windows to find what works best for your body and lifestyle.

Summary

Fasting is a common religious and cultural practice that may offer some health benefits when done correctly. If you want to try fasting, choose a method that suits your needs and listen to your body's signals throughout the process. Consult a healthcare provider before fasting, assess your progress and goals, and adjust your fasting plan as needed.

Read the original article on Verywell Health.