Our editorial team is made up of subject matter experts with extensive, real-world clinical experience who are highly trained in evaluating clinical research. Read more about our editorial policy here.
The Complete Guide to Intermittent Fasting
1. WHAT IS INTERMITTENT FASTING?
Fasting has been practiced across the globe in various religions and cultures for thousands of years. Recently the ancient practice of fasting has taken on new twists making it a very popular health and fitness trend.
It is known in the health and fitness world as intermittent fasting.
Intermittent fasting (IF) is a cyclic eating pattern that alternates between periods of fasting and eating. It is important to note that IF does not specify what types of food you should eat, rather focuses on when you should eat them. Intermittent fasting resembles more of an eating pattern than a diet because there are no calorie restrictions.
The various methods of intermittent fasting schedules include;
- 16:8 Method
- 5:2 Diet
- Eat-Stop-Eat Method
- Alternate - Day Fasting
- Warrior Diet
Amongst the various types of IF methods, the most popular style of fasting is the 16:8 method, which consists of a 16 hour fast.. Many intermittent fasters state that the 16:8 method is easy, convenient, and sustainable, increasing its appeal.
2. 16:8 INTERMITTENT FASTING?
16:8 intermittent fasting is a pattern of eating that allows you to have an 8 hour window of eating, and a 16 hour fast. A 16:8 IF can be repeated as often as you like, anywhere from daily to once or twice per week, depending on your personal preference.
Out of all of the different intermittent fasting methods, this method is considered the least restrictive and most flexible.
While there are many health benefits from 16:8 fasting, studies have shown that it can be particularly beneficial for athletes. Our article “Everything you need to know about intermittent fasting 16:8” discusses these benefits in detail. 16:8 IF has also been shown to have additional health benefits including weight loss, improved blood sugar, and increased brain function.
3. HOW TO INTERMITTENT FAST...
The first thing you should know about how long to intermittent fast and the 16:8 method, is that it is safe (assuming you do not have any underlying health conditions), simple, and sustainable. To get started, the first thing you need to do is pick an 8-hour window where you will consume your entire food intake for the day. Remember that your food intake should be limited only to your 8 hour window.
Many people schedule their 8 hour window of eating between noon and 8 PM. By doing so, you only fast overnight and skip breakfast. The time frame in the noon to 8 PM fast allows you to enjoy two balanced meals and a few snacks throughout the day.
Another popular time frame is an eating window of 9 AM to 5 PM. This option allows for a healthy breakfast around 9 AM, a normal lunch around noon, and a light early dinner or snack around 4 PM before your fast begins from 4 PM to 9 AM (next day).
Both fasting options allow adequate time for you to consume nourishing and healthy meals.
It doesn’t matter which option you choose, however consistency is important.
In order to maintain blood sugar levels, and keep hunger under control, it is important that the meals and snacks you consume are spaced evenly throughout your 8 hour eating window.
In order to ensure that you are receiving the adequate amount of nutrients, it is also equally vital that the type of food and beverages consumed during the 8 hour period are nutritious and whole.
Every meal and snack should include a variety of whole foods such as:
- Protein: Meat, poultry, eggs, fish, legumes, nuts, seeds, seafood.
- Healthy fats: Olive oil, coconut oil, avocados.
- Whole grains: Quinoa, brown rice, buckwheat, barley.
- Vegetables: Cauliflower, kale, spinach, broccoli, cucumbers
- Fruit: Bananas, apples, berries, oranges, pears.
It is important to note that during the fasting period, drinking non-caloric beverages is allowed. In fact, maintaining good hydration may also help curb hunger during the fasting period. Calorie free beverages such as water, unsweetened tea and coffee are good sources of hydration. Though 16:8 intermittent fasting does not have any food restrictions, binging on junk food can negate any positive effects that 16:8 intermittent fasting may have.
Therefore, make sure that you plan ahead to ensure that your 8 hour window of eating is filled with whole and nutritious foods, rather than fast food.
4. HEALTH BENEFITS OF FASTING
The simplicity, and convenience of 16:8 intermittent fasting makes it a very popular “diet.” Individuals following this eating pattern have found that the amount of time and money committed to food and preparation each week reduced once incorporating IF into their daily routines.
Simplicity and convenience aren’t the only benefits of 16:8 intermittent fasting. There are numerous health benefits associated with this eating pattern as well, such as:
- Increased Weight Loss: According to several studies published by the International Journal of Obesity, research has found that intermittent fasting for weight loss, even for a few hours per day, helps to decrease caloric intake as well as enhance the metabolism and increase weight loss.
- Improved Blood Sugar: A 2014 study found that intermittent fasting lowers blood sugar levels and reduces fasting insulin, which may help decrease the risk of diabetes.
- Enhanced Longevity: Preliminary research found that short-term, repeated fasting was an effective tool in prolonging the life span in mice.
- Increased Brain Function: A review article found that intermittent fasting may prolong the health-span of the nervous system, which may lead to new approaches for preventing neurodegenerative diseases.
5. INTERMITTENT FASTING MEAL PLAN
Before you start any intermittent fasting plan, it is important to talk to a health professional before you get started to ensure that it is right for you. There are mixed opinions on whether or not certain intermittent fasting protocols can cause female hormonal imbalances. Therefore, women should be especially cautious before starting an intermittent fasting eating regimen. If fasting for 16 hours is too difficult, consider shortening your fast to 14 hours.
To help get you started, here is a detailed 7-day meal plan for a 16:8 intermittent fast. This meal plan is designed for the following time frame: 12 PM – 8 PM eating window; 8 PM – 12 PM fast
During fasting period (8 PM – 12 PM):
- Drink non-caloric beverages (water, unsweetened tea & coffee)
Day 1
12:00 PM |
3:00 PM |
6:00 PM |
7:30 PM |
3 oz Grilled Chicken |
ATH Build Paleo |
3 oz. Grilled Salmon |
Banana |
2 cups Salad |
Double Chocolate |
½ cup Brown Rice |
Peanut Butter |
½ cup Quinoa ¼ Avocado |
Chip Cookie Bites |
2 cups Grilled Vegetables |
Raisins for topping |
Dressing: Olive oil & Balsamic vinegar |
|
Salmon Seasoning: olive oil, lemon, pepper, paprika, salt |
|
Day 2
12:00 PM |
3:00 PM |
6:00 PM |
7:30 PM |
Egg, Spinach, and Feta Omelet |
½ cup Whole Grain Pretzels |
Chicken and Vegetable Stir-Fry |
ATH Peanut Butter Build Shake |
¼ Avocado |
½ cup Hummus |
3 oz. Grilled Chicken |
|
1 slice Whole Wheat Toasted |
Celery Sticks |
Brown Rice Noodles |
|
|
|
2 cups Mixed Stir-Fry Vegetables |
|
|
|
Sauce: 2 tbsp. soy sauce, 2 tbs. oyster sauce, 2 tsp. sesame oil, garlic powder, salt, and cayenne to taste. |
|
Day 3
12:00 PM |
3:00 PM |
6:00 PM |
7:30 PM |
Taco Salad |
¼ cup Rolled Oats |
Kale and Sausage Rigatoni |
Dark Chocolate Almonds |
3.5 oz. Shredded Chicken |
Assorted Berries |
Pinch of Yum |
|
2-3 cups Lettuce |
Maple Syrup |
|
|
¼ Avocado |
|
|
|
¼ cup Pico de Gallo |
|
|
|
1 Whole-Wheat Tortilla |
|
|
|
Day 4
12:00 PM |
3:00 PM |
6:00 PM |
7:30 PM |
Whole Wheat Wrap |
Red Bell Pepper |
Baked Potato w/Sour Cream |
Apple Slices |
Lettuce |
Guacamole |
Steamed Vegetables |
Peanut Butter |
Tomatoes |
|
3 oz. Grass Fed Grilled Steak |
|
3 oz. Grilled Chicken |
|
|
|
Hummus |
|
|
|
Day 5
12:00 PM |
3:00 PM |
6:00 PM |
7:30 PM |
Avo and Egg Toast |
Cherry Tomatoes |
Sesame Noodle Bowls |
ATH Protein Waffles |
1-2 Slices Whole Wheat Bread |
Mozzarella |
From: Pinch of Yum |
Cottage Cheese |
1-2 Boiled Eggs |
|
|
Berries |
Avocado |
|
|
Honey |
Dash of cayenne, salt, and pepper |
|
|
|
Day 6
12:00 PM |
3:00 PM |
6:00 PM |
7:30 PM |
1 Whole Wheat Wrap |
Sliced Fruit |
Red Lentil Soup |
2 cups Popcorn |
½ cup Tuna |
Cheese |
From: NYT Cooking |
|
1 Boiled Egg |
|
Optional: ¼- ½ Avocado and Whole Wheat Roll |
|
Grated Cheddar Cheese |
|
|
|
1 Tomato (Sliced) |
|
|
|
1 handful Lettuce |
|
|
|
Day 7
12:00 PM |
3:00 PM |
6:00 PM |
7:30 PM |
Greek Lentil Power Bowls |
1 Hard Boiled Egg |
3 oz. Grass-Fed Beef |
ATH Probiotic Frozen Yogurt |
From: Nutrition to Fit |
Sliced Carrots and Cucumbers |
Whole-Wheat Buns |
|
|
|
Lettuce and Tomato |
|
|
|
1 slice Cheddar Cheese |
|
|
|
Olive Oil Roasted Sweet Potato |
|
6. FOOD GROUPS AND SERVING SIZES
It is important to remember that intermittent fasting is not a restrictive diet and does not follow a specific caloric value.
The following chart is a suggestion of serving sizes and types of food that you should eat. If you find that you are fully satiated with less food or require more food for optimal function, listen to your body.
Food Group | Minimum Daily Servings | 1 Serving Equivalents |
Carbohydrates (whole-wheat or whole-grain) | 6-8 Servings |
|
Protein | 2-3 Servings |
|
Healthy Fats | 2-3 Servings |
|
Vegetables & Fruit | 3-5 Servings |
Non-starchy vegetables:
Starchy vegetables:
Fruit:
|
Dairy | 2.5 Servings |
|
IMPORTANT THINGS TO REMEMBER
There are many different ways you can choose to fast. Experiment and pick a time frame that works for you and your schedule. Before you start any type of intermittent fasting regimen, talk to your doctor or healthcare professional, especially if you have any underlying health conditions.
16:8 intermittent fasting is an easy, and simple eating pattern that can help aid in weight loss and provide other health benefits. It is important to always listen to your body, and to fuel your body during your eating window with whole and nutritious foods. Hydration is also very important. Maintaining hydration with non-caloric beverages throughout the day is vital.