Skip to main content

How to Do Intermittent Fasting

Written by Andrew Le, MD

UpdatedFebruary 22, 2024

Intermittent fasting has garnered widespread attention for its promising impact on weight management and overall well-being.

The concept revolves around alternating between eating and fasting periods, offering a means to regulate calorie intake, enhance metabolic health, and potentially foster weight loss.

Studies reveal that adhering to this approach led to a notable reduction of 4-7% in waist circumference over 24 weeks. This signifies a tangible loss of harmful belly fat, which tends to accumulate around vital organs.

In this comprehensive guide, you will learn how to do intermittent fasting and its potential advantages. You will also know the possible side effects, safety considerations, and practical tips for seamlessly incorporating intermittent fasting into your lifestyle.

🔑 Key Takeaways:

  • Intermittent fasting focuses on when you eat rather than what you eat, mimicking historical periods of food scarcity. It involves cycling between fasting and eating windows, with various methods such as 16-hour daily fasts or 24-hour fasts twice a week.
  • Intermittent fasting may lead to weight loss, improve metabolic health, and potentially manage inflammation-related conditions. However, long-term effects are not fully understood, and individual responses vary.
  • Initial side effects like hunger and fatigue may occur but often diminish over time. It's crucial to be aware of potential side effects and consult a healthcare professional, especially during adjustment.
  • Intermittent fasting is generally safe but may not be suitable for individuals under 18, those with a history of disordered eating, pregnant or breastfeeding individuals, athletes, or those with certain medical conditions.
  • Choose from various methods like fasting for 12 hours a day, 16:8 method, 5:2 diet, alternate day fasting, weekly 24-hour fast, or the Warrior Diet. Gradual progression, balanced meals, and hydration are key aspects.
Illustration of a healthcare provider asking questions on a smart phone.
Virtual weight loss solution
A personalized GLP-1 medication program (eg. Wegovy, Ozempic), delivered to you via our partner Korb Health
Illustration of a healthcare provider asking questions on a smart phone.
  • Free consultation; program starts at $269/mo
  • Checkmark Inside Circle.Customized online program and wellness coaching
  • Prescription medications and supplies shipped to your door

Understanding Intermittent Fasting

Intermittent fasting shifts the focus from what you eat to when you eat. The concept involves cycling between periods of fasting and eating. Unlike traditional diets that prescribe specific foods, intermittent fasting defines clear eating windows.

Historically, humans evolved as hunter-gatherers, adapting to periods of scarcity where finding food wasn't guaranteed. In modern times, however, our constant access to food and sedentary lifestyles have contributed to health challenges like obesity and diabetes.

Intermittent fasting aims to harness the body's ability to function without constant fuel intake. Common methods include daily 16-hour fasts or fasting for 24 hours twice a week. Fasting, rooted in centuries-old practices, isn't merely a modern trend. It has deep historical significance, influenced by factors like food scarcity and religious beliefs.

💡 Did You Know?

Between keto and intermittent fasting, keto trims carbs and boosts fats for rapid weight loss, but be mindful of nutrient issues and side effects. On the other hand, intermittent fasting, cycling between eating and fasting, offers flexibility and lasting health benefits, yet it might only be a fit for some.

Benefits of Intermittent Fasting

Intermittent fasting offers several potential benefits, particularly in the short term. Some of these benefits include:

  • Weight Loss: Intermittent fasting can lead to weight loss by promoting ketosis, where the body burns stored fat for energy due to reduced glucose availability. Research suggests it can be as effective as traditional counting-calorie diets.
  • Metabolic Improvements: Fasting can positively impact metabolic processes, potentially reducing inflammation, improving blood sugar regulation, and enhancing the body's response to physical stress.
  • Health Conditions: Some studies suggest intermittent fasting may help manage inflammation-related conditions, such as arthritis, asthma, and multiple sclerosis.

However, it's important to note that the long-term health benefits and risks of intermittent fasting still need to be fully understood due to limited research in this area.

Side Effects of Intermittent Fasting

Intermittent fasting may have some side effects, especially during the adjustment period. These side effects can include:

Fortunately, most of these side effects diminish after the first month of intermittent fasting. Whether or not these side effects occur can vary from person to person.

Is Intermittent Fasting Right for You?

Intermittent fasting is generally safe for many individuals, but it may not suit everyone. It is not recommended for:

  • Individuals Under 18: Adolescents and children are still growing and developing, making fasting unsuitable for their nutritional needs.
  • History of Disordered Eating: People with a history of eating disorders should avoid intermittent fasting, as it can potentially trigger unhealthy eating behaviors.
  • Pregnant or Breastfeeding Individuals: Pregnant and breastfeeding women require consistent nutrition for their health and their babies.
  • Athletes: Athletes may need help to meet their energy needs and maintain their performance while fasting.
  • Medical Conditions: For those with diabetes or specific medical conditions, consulting a healthcare provider before beginning intermittent fasting is advisable.

It's crucial to emphasize that successful weight loss with intermittent fasting still depends on overall calorie intake. Overeating during eating windows can negate any potential benefits.

How to Do Intermittent Fasting

Source: Harvard

Now that you grasp intermittent fasting and its considerations, here are six popular ways to integrate it into your lifestyle:

1. Fast for 12 Hours a Day:

Embark on your intermittent fasting journey with a manageable 12-hour daily fast. Here's a step-by-step guide:

  • Choose a 12-hour fasting window that aligns with your daily routine, such as 7 p.m. to 7 a.m. For example, if you finish dinner by 7 p.m., the fasting period naturally includes your sleep time, making it more achievable.
  • Ensure your last meal concludes before the fasting window begins, with a well-balanced dinner at 6:30 p.m.
  • Stay hydrated during fasting with water or herbal teas to help curb hunger and support overall well-being.
  • Break your fast mindfully with a nutritious breakfast at the end of the 12-hour fasting period, for example, at 7 a.m. Consider a breakfast with proteins, healthy fats, and carbohydrates.

2. Fasting for 16 Hours (16:8 Method)

Opt for a 16-hour daily fasting period with an 8-hour eating window. Follow these steps:

  • Select a 16-hour fasting window, like 8 p.m. to 12 p.m., allowing for extended fasting.
  • Ensure your meals during the 8-hour eating window are balanced, including proteins, healthy fats, and carbohydrates. For instance, have your first meal at noon: lean protein, vegetables, and whole grains.
  • If new to fasting, start gradually with shorter fasting periods before progressing to 16 hours. Begin with a 12-hour fast and progressively extend it by an hour over several days or weeks.

3. Fasting for 2 Days a Week (5:2 Diet)

Adopt the 5:2 diet, incorporating regular and fasting days. Here's how:

  • Consume a regular diet for five days, meeting nutritional needs. For example, eat a balanced diet with fruits, vegetables, lean proteins, and whole grains.
  • Restrict calories to 500-600 on two non-consecutive fasting days. Strategically plan these on less active days.
  • Strategically plan an intermittent fasting schedule, separated by non-fasting days. Consider choosing Mondays and Thursdays for fasting, allowing at least one non-fasting day in between.

4. Alternate Day Fasting

Engage in alternate-day fasting, adjusting solid food intake. Follow these steps:

  • Define fasting days, deciding whether to avoid solid foods entirely or allow up to 500 calories. For instance, consume only water, herbal teas, or broths on fasting days.
  • On non-fasting days, eat as desired. Ensure to include nutrient-dense foods like vegetables, fruits, and lean proteins.
  • Monitor nutrient intake on feeding days to compensate for potential gaps. Focus on a well-rounded diet to ensure your body receives essential nutrients.

5. Weekly 24-Hour Fast (Eat-Stop-Eat Diet)

Incorporate a weekly 24-hour fast for calorie reduction. Here's a guide:

  • Start gradually with shorter fasts before attempting a complete 24-hour fast. For instance, begin with a 16-hour fast and then progress to a 24-hour fast once a week.
  • Consume only water, tea, or calorie-free drinks during the 24-hour fasting period. Stay well-hydrated to support your body during the extended fast.
  • Resume regular eating patterns on non-fasting days, ensuring meals are nutritionally dense. Plan well-balanced meals with a variety of nutrients.

6. The Warrior Diet

Explore the Warrior Diet, a more extreme form of intermittent fasting, with these steps:

  • Embrace a 20-hour fasting window, consuming small portions of raw fruits and vegetables. For example, eat small salads, fruits, or raw veggies during this period.
  • Dedicate a 4-hour eating phase for a larger, balanced meal, usually in the evening. This could include lean proteins, healthy fats, vegetables, and carbohydrates.
  • Adjust the eating phase based on personal preferences, maintaining nutritional balance. Experiment with different food combinations to find what suits your taste and lifestyle.
  • Be cautious with consuming a large evening meal close to bedtime, experimenting with meal timing to suit individual preferences and sleep patterns. Consider having a larger meal a few hours before bedtime to allow for digestion.

Intermittent Fasting Diet Plan

Having an intermittent fasting diet plan is a strategic approach to improve weight management, boost metabolic health, and foster overall well-being. Here are samples for intermittent fasting meal plan:

Basic Intermittent Fasting Meal Plan for Beginners

8 a.m. - Breakfast

Green Smoothie

  • 1 avocado
  • 1 cup coconut milk
  • Small handful blueberries
  • 1 cup spinach, kale, or chard
  • 1 tablespoon chia seeds

12 p.m. - Lunch

Nutrient-rich Beef Patties

  • ½ pound ground lean grass-fed beef
  • ½ pound ground grass-fed beef liver
  • ½ teaspoon garlic powder
  • ½ teaspoon cumin powder
  • Sea salt and pepper to taste

2:30 p.m. - Snack

Cinnamon Roll Fat Bombs

  • ½ cup coconut cream
  • 1 teaspoon cinnamon
  • 1 tablespoon coconut oil
  • 2 tablespoons almond butter

5:30 p.m. - Dinner

Lemon-Garlic Roasted Salmon

  • 1 pound salmon or preferred fish
  • 2 tablespoons fresh lemon juice
  • 4 cloves garlic, minced
  • 1 tablespoon olive oil
  • Salt and pepper to taste

Intermediate Intermittent Fasting Meal Plan

12 p.m. - First Meal

Grass-fed burger with Avocado

2:30 p.m. - Snack

Nuts and Seeds

5:30 p.m. - Second Meal

Salmon and Veggies

Advanced Modified 2-Day Meal Plan

Clean eating for five days, restricted calories (700 max) on two non-consecutive days:

  • On clean eating days: Focus on healthy fats, clean meats, vegetables, and fruits.
  • On restricted days: Smaller meals or snacks throughout the day or a moderate-size lunch and dinner with fasting in the morning and after dinner.

Tips for Successful Intermittent Fasting

Maintaining a routine for this approach can be challenging, but these tips can help you achieve a successful intermittent fasting result:

  • Stay Hydrated: Stay hydrated during fasting with water and calorie-free herbal tea.
  • Distract Yourself: Keep busy with distractions on fasting days to avoid focusing on food, such as engaging in work or leisure activities.
  • Rest and Relax: On fasting days, skip intense activities; opt for gentle exercises like yoga.
  • Choose Nutrient-Dense Foods: Opt for nutrient-dense foods during eating windows, including fruits, vegetables, whole grains, lean protein, and low-fat dairy.
  • Eat High-Volume Foods: Opt for filling, low-calorie foods like raw veggies and hydrating fruits to curb hunger.
  • Enhance Flavor Without Calories: Season your meals with herbs, spices, garlic, or vinegar to add flavor without adding calories.

🗒️ Related Articles:

Effective weight management is vital to a healthy lifestyle, balancing calories and well-being. Check out more of our articles:


Intermittent fasting is a versatile approach to weight management and potential health benefits. While it may only suit some, it can be an effective tool when used correctly.

By choosing the correct method, staying consistent, and focusing on balanced nutrition, you can harness the power of intermittent fasting to support your health and wellness goals.

Remember that long-term research is still evolving, and individual experiences may vary, so monitor your progress and adjust as needed to achieve the best results for your unique body and lifestyle.

FAQs on Intermittent Fasting

What is the best intermittent fasting window to lose belly fat?

The effectiveness of an intermittent fasting window may vary from person to person. However, the 16/8 or 18/6 intermittent fasting windows are often recommended for targeting belly fat. Choosing a window that aligns with your lifestyle and preferences is crucial.

What is 18/6 intermittent fasting?

18/6 intermittent fasting is a fasting protocol where you fast for 18 hours and have a 6-hour eating window. This approach is famous for its potential weight management and metabolic health benefits.

Can you provide a 16/8 intermittent fasting 7-day meal plan?

While individual nutritional needs vary, a sample 16/8 intermittent fasting meal plan may include balanced meals within the 8-hour eating window, emphasizing whole foods, lean proteins, fruits, and vegetables. Consulting with a nutritionist can help create a personalized plan.

How long does it take for 16/8 intermittent fasting to work?

The time it takes to see results with 16/8 intermittent fasting can vary. Some people may notice changes in a few weeks, while others may take longer. Consistency is key, and individual factors such as metabolism and activity levels play a role.

Is intermittent fasting suitable for women?

Yes, intermittent fasting can be suitable for women. However, it's essential to consider individual health conditions and needs. Women may benefit from modified fasting approaches; consulting with a healthcare professional is advised.

Why use an intermittent fasting app?

Intermittent fasting apps help track fasting and eating windows, provide reminders and offer insights into your progress. They can be valuable tools for maintaining consistency and staying accountable to your intermittent fasting goals.

How to do intermittent fasting?

To practice intermittent fasting, choose a fasting window, like the popular 16/8 or 18/6 methods, designating hours for eating and fasting. Plan balanced meals rich in whole foods during the eating window and stay hydrated with non-caloric beverages during fasting periods. Gradually adjust to fasting, listen to your body's cues, and prioritize consistency.

Illustration of a healthcare provider asking questions on a smart phone.
Virtual weight loss solution
A personalized GLP-1 medication program (eg. Wegovy, Ozempic), delivered to you via our partner Korb Health
Illustration of a healthcare provider asking questions on a smart phone.
  • Free consultation; program starts at $269/mo
  • Checkmark Inside Circle.Customized online program and wellness coaching
  • Prescription medications and supplies shipped to your door