#89 - AMA #11: All things fasting
In this AMA sneak peek, host Peter Attia, joined by Bob Kaplan, defines various fasting protocols including TRF, ADF, FMD, and prolonged fasting. He also shares his personal approach to fasting, including his stance on coffee and tea during a fast.
Deep Dive Analysis
9 Topic Outline
Introduction to Fasting Definitions
Defining Overnight Fast
Understanding Time-Restricted Feeding (TRF/TRE)
Explanation of Alternate Day Fasting (ADF)
Clarifying Intermittent Fasting (IF) Terminology
Overview of the 5-2 Fast Protocol
What is a Fasting Mimicking Diet (FMD)?
Defining Prolonged or Multiple Day Fasting
Considerations for Coffee and Tea During a Fast
7 Key Concepts
Overnight Fast
This is the standard period of not eating that occurs between dinner and breakfast, typically lasting around 12 hours, for example, from 7 PM to 7 AM.
Time-Restricted Feeding (TRF/TRE)
TRF or TRE is a protocol that extends the overnight fast into a longer window, defining a specific period for eating (e.g., 16 hours fasting, 8 hours eating) where food intake is usually ad libitum within the designated eating window.
Alternate Day Fasting (ADF)
Alternate Day Fasting involves a person doing something other than their traditional ad libitum eating every other day. This can range from consuming literally nothing to a hypocaloric intake of around 1,000 calories on the 'fasting' days.
Intermittent Fasting (IF)
Peter Atiyah finds this term unhelpful as it's often used interchangeably with time-restricted feeding. He suggests a more accurate meaning would be periodic, prolonged fasts, such as those undertaken monthly or quarterly, rather than daily extended overnight fasts.
5-2 Fast
The 5-2 fast is a weekly protocol where individuals eat normally for five days and consume a significantly reduced calorie intake, typically 400 to 600 calories, on two non-successive days.
Fasting Mimicking Diet (FMD)
The term Fasting Mimicking Diet (FMD) is a trademark belonging to a company that sells a pre-packaged five-day reduced-calorie diet. It has a clear prescription around its macronutrients and total caloric balance, designed to approximate some of the metabolic benefits of fasting.
Prolonged Fasting (Water-Only)
This refers to absolute fasting, where only water, tea, and some minerals are consumed, with no caloric intake whatsoever. It is typically undertaken for periods of three to seven days at a time.
9 Questions Answered
An overnight fast is the standard period of not eating that occurs between dinner and breakfast, typically lasting around 12 hours (e.g., 7 PM to 7 AM).
TRF/TRE involves extending the overnight fast into a longer window, such as a 16-8 protocol (16 hours fasting, 8 hours eating), where food is consumed ad libitum within the eating window.
Alternate Day Fasting means a person abstains from traditional ad libitum eating every other day, which can range from consuming literally nothing to a hypocaloric intake of around 1,000 calories on the 'fasting' days.
Peter Atiyah finds the term 'intermittent fasting' unhelpful as it's often used to mean time-restricted feeding; he suggests it should refer to periodic, prolonged fasts (e.g., monthly or quarterly).
The 5-2 fast involves eating normally for five days of the week and consuming a hypocaloric diet (typically 400-600 calories) on two non-successive days.
A Fasting Mimicking Diet (FMD) is a trademarked, pre-packaged five-day reduced-calorie diet, based on specific macronutrient and caloric prescriptions, designed to approximate the metabolic benefits of fasting.
Prolonged fasting, in its strictest sense, is a water-only fast (including tea and some minerals) with no caloric intake, typically undertaken for three to seven days.
For patients who are highly caffeine-dependent, coffee may be allowed to avoid caffeine withdrawal, though Peter Atiyah personally avoids it for the first five days of long fasts, sometimes having black coffee as a treat later.
Tea is generally considered more forgiving than coffee during a fast, and many types contain caffeine, making it a suitable option for hydration and potentially caffeine intake.
11 Actionable Insights
1. Practice Prolonged Water Fasting
Engage in absolute fasting by consuming only water, tea, and some minerals for a period of three to seven days, ensuring no caloric intake.
2. Practice Time Restricted Eating
Extend your overnight fast to a longer window (e.g., 14-10, 16-8, 18-6), where the first number is the fasting period and the second is the eating window, consuming food ad libitum during the eating window.
3. Implement Alternate Day Fasting
Follow alternate day fasting by consuming a hypocaloric diet (e.g., ~1,000 calories) every other day, while eating ad libitum on non-fasting days.
4. Follow 5-2 Fast Protocol
Implement the 5-2 fast by choosing two non-successive days per week to consume a hypocaloric diet (typically 400-600 calories), eating normally on the other five days.
5. Explore Reduced Calorie Fasting
Consider doing a reduced calorie fast that approximates some of the metabolic benefits of fasting, even if not using a specific commercial product, by carefully managing caloric intake.
6. FMD Caloric Intake Guideline
If attempting a fasting mimicking diet, aim for approximately 900-1000 calories on day one, and 700-750 calories for days two through five, based on the commercial FMD product’s structure.
7. Manage Caffeine During Fast
If you are caffeine dependent, do not eliminate caffeine during a fast to avoid the added challenge of caffeine withdrawal, as fasting is already difficult.
8. Avoid Coffee for Gut Rest
If your fasting protocol specifically includes gut rest, definitely avoid coffee due to its phytochemicals, which can interfere with the intended gut rest.
9. Coffee Intake During Prolonged Fast
If not caffeine dependent, consider abstaining from coffee during the initial days of a prolonged fast (e.g., first five days) and potentially using black coffee as a treat on later days (days 5-7) to break up boredom.
10. Use Tea During Fasting
When fasting, tea can be a more forgiving option than coffee, especially if caffeine is desired, as it contains caffeine and appears to be less problematic for gut rest than coffee.
11. Use Bubbly Water During Fast
Incorporate bubbly water during a fast to break up the monotony and make the experience more varied.
3 Key Quotes
A black coffee has never tasted so good as it does on day five of a water only fast.
Peter Atiyah
I don't really think it benefits someone to also go through caffeine withdrawal during that period of fasting.
Peter Atiyah
There are an infinite number of tissues that you can blow your nose into. There's only one Kleenex.
Peter Atiyah