Deciding what diet strategy to follow is a complex and highly individual decision. Weight loss and nutrition are some of the most difficult and confusing topics in modern wellness. Use this guide to select a protocol, track your progress, and adjust the process to work for you. We encourage you to think of your eating habits in the context of a lifestyle as opposed to a short-term "diet." Cut through the thicket of dietary supplements and complicated regimens and try intermittent fasting.
Step 1: The Protocol
The main variables in any fasting protocol are the length of the feeding windowvs the fasting window. Two of the most popular protocols are a daily 16:8 (LeanGains) or a weekly 5:2 (Monk) fast.
The 16:8 (LeanGains) fast is based on a daily "feeding window."
- Fast for 16 hours (ex: stop eating at 8pm and resume eating at noon the next day). During the fast, water, coffee, and tea are acceptable beverages (because they contain no calories).
- Eat as normal, without calorie restriction, for the remaining 8 hours.
The 5:2 fast (Monk Fast) is ideal for people who want to take fasting to the next level without completely overhauling their lifestyle. This involves 2 36-hour fasts per week.
The fast days can be selected for convenience. An example protocol is:
- Stop eating at 8pm on Sunday night.
- Fast throughout the day on Monday. Water, tea, coffee, and bone broth are encouraged to stay hydrated.
- Eat breakfast as usual at 8am on Tuesday. Eat normally on Wednesday and Thursday.
- Stop eating at 8pm on Thursday night. Follow the fasting protocol all day Friday, and break your fast at 8am on Saturday.
- It's important to stay hydrated! Drink plenty of water while fasting. If you do not hydrate properly, you are far more likely to feel weak or ill.
- Sparkling water can be extremely helpful in keeping your mouth and palate occupied. If you choose a brand with flavoring, be careful to read the labels and make sure there are no added sugars or calories.
- If you start your fast directly after dinner (say, 8pm), a big chunk of the fast will be completed before you wake up the next morning.
- Do not schedule your fasts for subsequent days (ie: if your fast goes from Sunday night to Tuesday morning, do not start fasting again on Tuesday night). As you adapt to fasting, this may no longer apply to you.
- The WeFast Facebook group is a great community that offers support and advice for beginners and fasting pros alike.
- Fasting and the feeling of being hungry is often an unusual or uncomfortable sensation at first. There is a difference between this discomfort and truly feeling unwell. Challenge yourself but do not push past what's safe. The feeling of hunger (your body asking for resources) will recede as you adapt away from a carbohydrate dependent state and go into a fat burning state.
- If at first you have difficulty fasting for the full time period, don't be discouraged! Fasting, like anything else, takes practice.
If you are successful at doing weekly fasts, you can build up to longer fasts. These should not be done frequently, but can be a great way to jumpstart ketosis and autophagy or "reset" the body and your eating habits.
A 3, 5, or 7 day water fast is challenging but can amplify the benefits you experience from a short weekly fast.
- Consume only water, black coffee, and tea. Especially if exercising, a pinch of salt may help replenish electrolytes. When doing a long fast, drinking enough water is absolutely essential! Dry fasting, or abstaining from water, can be extremely dangerous and we do not recommend it.
- After 24-36 hours you will be in ketosis - your body adapts to burn fat. The weight loss that people notice during longer fasts is partially water and partially fat burning!
- Many people have no problem doing their usual exercise routine while fasting for longer periods of time. However, be sure to start slowly and not overdo it - fast week is not the time to go all out until you have adapted.
- Break the fast slowly - soup and avocados are popular choices.
The Fast-Mimicking Diet is another way to extend the benefits of IF without having to water fast. The inventor of the diet, Dr. Valter Longo, sells the products needed for the fast, but it is possible to create your own version without the proprietary ingredients.
The diet runs on a 5 days on/25 days off cycle.
- Day 1: Eat 1090 calories. The macros should be 34% carbs, 10% protein, and 56% fat. Days 2-5: Eat 725 calories. The macros should be 47% carbs, 9% protein, and 44% fat.
- Days 6-30: Eat normally.
To maximize the effects, you can repeat this 30 day cycle 3 or 4 times. Check back for more information on how to put together your own version of the diet.
Step 2: Measurements to Track
A primary goal for many people who try IF is weight loss or improving body composition. However, it has been shown to improve other measures of health such as cognition, metabolism, longevity, and immunity.
Measurements to track on the macro level include:
- Weight - this is an obvious choice for most people. Level up by using a smart scale that can graph your progress over time. It's important to not be discouraged by the number on the scale as weight can fluctuate due to water retention and other factors. Instead, consider it a rough estimate of progress.
- Body measurements - this is a more accurate and rewarding way to track progress for most people. Good measurements to track weight loss include the waist, hips, thighs, and neck.
- Photographs - a weekly picture in front of the mirror is an easy way to see trends and progress over time!
- Body fat percentage - this can be tracked roughly at home by purchasing body fat calipers. A full body DEXA scan is a more accurate option, but may be impractical due to the expense.
- Tracking macronutrients is an effective way to hack your diet. This is particularly helpful if you are trying to "bulk" or build mass.
Measurements to track molecular markers of health include:
- Blood glucose - can be measured with the traditional finger stick method. If you don't want to prick your finger, a continuous glucose monitor can be used to visualize your glucose control (and indirectly, your insulin response) over time.
- HbA1c - this is a long term picture of your blood sugar levels. It essentially reflects what percentage of your red blood cells have glucose attached to them. This test must be performed by a healthcare professional.
- Cholesterol - significant changes are usually only seen over a period of 6 months. This test must be performed by a healthcare professional.
Step 3: Optimization
- If you find a 36 hour fast difficult: you can consume up to 500 calories without losing all the benefits of the fast. This can be an effective crutch until you are used to fasting and can make it through the day without them. Choose good fats to help yourself feel fuller - examples are a tablespoon of coconut oil or olive oil. If you eat protein, you will lose the benefits of autophagy (destruction of damaged or dysfunctional cells), which is one of several benefits to IF.
- Working out: many people have had success with all types of workouts while fasted. This includes heavy lifting. When starting out, schedule lighter workouts like gentle cardio or yoga on your fasting days. You can also do your normal routine at 50-75% intensity and then ramp it up as you adjust.
- If you want to take it up a notch: The 5:2 fast can be converted to a 4:3 program for those who want to take a more aggressive approach. This program may be particularly suitable for diabetics.
- To get some of the health benefits without the weight loss component: try a 6:1 fast.
Studies have shown that intermittent fasting is just as effective as daily caloric restriction for weight loss results1. Fasting may be more sustainable than traditional dieting since it takes less effort and willpower. We recommend intermittent fasting as a superior method over daily caloric restriction for weight loss.
Intermittent fasting can be a positive experience for diabetic patients, but must be coordinated with a doctor knowledgeable about IF and adjusting insulin and other medication doses. Fasting is also not a suitable protocol for pregnant women or children who are still growing and need calories and nutrients. Although there is anecdotal evidence of eating disorder recoverers succeeding at incorporating IF into a healthy lifestyle, these individuals should take extra care when deciding if this is right for them. Healthy women may also need to modify the protocol for optimal results. If you have any doubts, you should consult a doctor to see if IF is right for you.
More information on the science of intermittent fasting and its effects on can be found here.
Intermittent fasting can also be used in conjunction with other special diets such as vegetarian/vegan or ketogenic. The ketogenic diet (or eating low carb high fat) is a method for further optimizing your fasting regimen. However, the most important thing is finding a diet that works for your lifestyle, since the emphasis in fasting is on WHEN you eat, not WHAT.