Choosing a fasting method can be a challenge due to:
A) confusion over different types of fasting, and
B) little specific information on how each fast supports fat loss.
We’ve built a framework to give you clarity and help you identify the best fasting method for your situation. It's based on a combination of our review of research studies and our experience working with clients.
What Are the Different Types of Fasting Methods?
There are six different types of fasting methods to choose from but they all have one thing in common. Each method will put you into a calorie deficit that helps you to lose fat over time. Fasts are grouped into either short fasts (also known as intermittent), or long fasts.
Short fasts
Time Restricted Feeding (TRF): This type of fast is up to 16 or 18 hours. People who have no experience with fasting generally start here.
Modified Fasting: A one-day off and one-day on fasting method that allows you to intake up to 350 kcal on the days you fast. For example, a Hass avocado has about 350 kcal and would be safe to consume on your fast days. This method of fasting is also useful for those who take medications that require food.
Alternate-Day Fasting: This type of fast is just as it sounds. One day you fast then the next day you eat normally. This is repeated throughout the week and is usually for more experienced fasters.
Short-Term Fasting: A 72-hour fast that is for more experienced fasters. This type of fast is often used to help break fat loss plateaus.
Long Fasts
Fasting Mimicking Diet (5 Days): Much like the modified fasting method except prolonged for five days. Every day you can have up to 700 kcal of food and drinks.
Prolonged Fasting: This type of fast is longer than 72 hours or more.
The Differences Between Fasting Methods
The main difference between fasting methods is whether you attain ketosis which depends on the length of time of your fast. The production of ketones is what helps you to feel less hungry over longer periods of time and eat less when you break your fast.
Short fasts (with the exception of alternate-day fasting) do not get you into ketosis.
Long fasts will get you into ketosis and are also useful when your fat loss progress has stalled.
Prolonged fasting will get you into ketosis but is not recommended for fat loss in isolation. It has been demonstrated within the research that people tend to regain much of the weight they had lost when used as the sole method of fasting.
Here is a simple diagram to help you remember:
Type Of Fast | In Ketosis | Length Of Fast | Specific Use | Experience Level |
Time Restricted Feeding | No | 16-18h | To Start | Beginner |
Modified Fasting | No | 24h | For Medications* That Need Food | Intermediate |
Alternate-Day Fasting | Possibly* | 24h | Fat Loss Plateaus | Experienced |
Short Term Fasting | Yes | 72h | Fat Loss Plateaus | Experienced |
Fasting Mimicking Diet (5 Days) | Yes | 5 days | Fat Loss Plateaus | Experienced |
Prolonged Fasting | Yes | More than 72h | Not Suggested For Fat Loss Goals* | Experienced |
* Will possibly get you into ketosis based on your personal metabolism and keto-adaptation
*Modified fasting makes it easy to fast even when your medication requires food
*Prolonged fasts are not suggested for fat loss goals due to quick regain after completion
Choosing Your Optimum Fasting Method for Fat Loss
From working with clients we have found that the best choice is the fasting method that combines two factors:
First, and most important, it’s sustainable for you. Meaning you can maintain the practice without too much effort.
Second, it maximizes your calorie deficit.
To simplify the choice for you, we’ve developed a fasting method optimisation tool that creates your fasting method program for you. This tool leverages the framework we’ve outlined in this article, asking you a few specific questions to identify a program adapted to your situation.
When using this tool consider some of the following factors:
Lifestyle Fit: To make any lifestyle change sustainable we need to engineer it to work as effortlessly as possible with your existing lifestyle constraints. Examples are whether you need to take medication with food or whether you have limited windows where you can make meals. Selecting fasting methods that work with vs. against these constraints always works better.
Foundation vs. Sprint: Over time we’ve found that clients optimise results through a combination of fasting methods in their program. They have a foundation fasting method that is relatively effortless for them to maintain and they follow every week. Then, from time to time, when they have some additional space or willpower, they will take on a fasting sprint. A fasting sprint is where you take on a higher calorie deficit fasting method for a limited time (e.g. a day, two days or a week). While you can’t sustain the method you use with a fasting sprint, when used strategically from time to time, it is both realistic and improves your fat loss results.
Metabolic Experience: If you are already on a keto diet you will likely find that fasting is easier due to your metabolic adaptations and specifically your pre-existing ketone levels. The appetite-reducing ketones that you create lower your sensation of hunger allowing you to fast for longer. C8 MCT oil can be used in the same way, even if you are not on a keto diet, and keep you fasting for longer.
Actionable Takeaways
To sum up, there are many different methods but to make things easy for you to choose just remember these points:
The best fasting method is the method that works best for you and your lifestyle
Sixteen-hour fasts are a good place to start if you have no experience with fasting
If you have done the keto diet before longer fasts may be easier to complete
C8 MCT oil can help you prolong your fast and stay satiated
Need More Help?
If you have any questions please contact us for further assistance. Leave your name and email, and one of our nutritional analysts will get back to you to help you on your fat-loss journey.