The Fast Five Lifestyle


Scott Carney’s book, What Doesn’t Kill You… mentions something called “the fast five diet”.  It is an official fad diet, which is based around the idea of only eating within a small window each day, and fasting the rest of the time (water, tea, etc okay).  The official diet got its name by making that window five hours long, usually something like 5-10pm (the specific time window doesn’t matter as long as it’s about the same each day).  Scott Carney mentions it only because Wim Hof’s diet just happens to be similar to the Fast Five diet.  It’s not because Wim Hof is a fad dieter, it’s that his body doesn’t ask for food most of the day, so he only eats within a small window.  And if you know Wim Hof, he always advises you to “listen to your body.”

There’s a few research-supported health benefits that can be attributed to letting your digestive system rest most of the day.  However, there’s also two WHM-specific benefits:

  1. An empty stomach leaves extra space for your lungs and diaphragm to do their work
  2. Your body won’t be spending energy on digestion while you are doing the exercises.  Retentions should be longer, your body should be quieter.

I never gave much thought to it other than liking the concept when I first learned about it.  I’ve been a big fan of fasting for a long time, and this seemed to be kind of intermittent fasting that would probably have similar benefits.  But I never considered actually doing it.

WHM Advanced Module in LA

I was introduced to two things when I went to LA for the WHM course.  The first was “Bulletproof coffee”, which is a thing in LA (apparently).  It’s adding a few teaspoons or tablespoons of butter and MCT oil to a cup of coffee in the morning.  It’s advertised as brain food, because the MCT oil contains specific subsets of fats that are supposedly easily consumed by your brain for energy.  I’m not sure how much I believe that, but that wasn’t my motivation anyway.  It’s a new “tool” I can add to my toolbox for when I do fasting.  Fasting benefits greatly from pure fats which limit your appetite and encourage ketosis, which is the mode your body into when it switches from burning carbs for fuel to burning fat.

The second thing was a Hoffer from Toronto who is (kinda) a physical therapist who does the fast-five diet mostly for the same reason Wim Hof does it.  He just doesn’t feel like eating most of the day.  However, he only does it during the week, and “catches up” on the calories on the weekend when he spends time with his family.

These two things together inspired me.

Other Inspiration – FMD

Before I talk about my recent experiences, I want to reflect on my previous encounters with fasting.  First of all, I’m a firm believer in CRON:  “calorie restriction with optimal nutrition.”  Though, just because I believe in it doesn’t mean I’m willing to suffer through such a huge lifestyle shift, no matter how potent the potential benefits (look it up, it’s impressive).

Then, a couple years ago, my wife and I fell for the “fasting-mimicking diet” (FMD), which is described pretty thoroughly here:

I initially looked at this with a skeptical eye, since the main researcher (Dr. Longo) started a company around promoting this diet, so I recognize there are inherent conflicts of interest.  However, he has been studying fasting and longevity for decades, and only recently started the company because he claims the results of his research were so promising.  But who knows…

Regardless of his motives, it inspired me to do some research on fasting in general, which led me to believe that this was both safe and likely to have at least some of the benefits Dr. Longo claims in his research.  I also asked my primary doctor about the idea of consuming 725 calories/day for 5 days each month.  His response was:

I don’t know about this specific diet, but there’s very little damage you can do to yourself in five days unless you are consuming bad stuff in large quantities.  At various points through their lives, most people go through severe calorie reduction like this when they get really sick yet suffer no long-term effects besides losing a little weight.


My wife and I did it three times before she got pregnant with our first child, and it was fantastic.  The extremely high ratio of fat made the food enjoyable and suppressed our appetites to an astounding degree.  We couldn’t believe that our hunger levels were so low despite consuming 1/3 our normal calories.  We suffered a little bit here and there (especially the last night), but for the weight loss and supposed benefits, it seemed way too easy.

This also inspired me to do research on fats in general, and now firmly believe that they have been unfairly demonized.   My main takeaway from all of it is that replacing a few hundred calories from carbs per day with calories from fat is probably pretty good for you.  At worst, it’s not doing any harm.  At best, it’s improving nutrient absorption and limiting your appetites so you might eat fewer calories throughout the day.

The 5×5 Bulletproof Lifestyle

The downside of FMD is that requires planning out your meals, and best done with a buddy.  With a pregnant-then-breastfeeding wife, she wasn’t a candidate to do it with me in the near future.  I needed something else.

So I made my own diet/lifestyle (and my own name for it), inspired by everything I’ve written here.   Monday through Friday, I wake up in the morning and make myself coffee with about 1/2 tbsp of butter (yes, grass-fed, though I seriously doubt it matters that much), and 1/2 tbsp of MCT oil.  I also add a little bit of sugar or splenda, half&half.  It’s probably 150-200 calories of almost-pure fat in my coffee.

I nurse that throughout the morning, then I don’t eat anything until 4:30pm except sometimes tea in the mid-afternoon.  After 4:30pm I allow myself to eat extra calories to make up from some (or even all!) of the calories I would’ve eaten earlier in the day, but stay very mindful of my goals and try really hard not to overdo it.   Then I avoid consuming anything after 9:30pm, which is a good rule to have regardless of your dieting status.

The research on this kind of “intermittent daily fasting” seems to suggest benefits to doing this even if you ultimately eat the same number of calories in that eating window as you otherwise would.  And to be fair, it doesn’t take a lot of self-restraint to cut down overall calories when you do this.  There are benefits to letting your digestive system be at rest periodically, and since glucose levels tend to run low after 8-12 hours you will spend at least a few hours per day in ketosis.  I even bought ketone urine strips to confirm that I really go into ketosis.  Yes, I do! (but not high on the scale)

This has been super easy to follow, requires no planning, and is minimally stressful.  It also frees up a bunch of mental cycles I’d normally spend throughout the day controlling my snacking habit, deciding what to eat for breakfast and lunch.  Sometimes I find myself restless around 3pm which is certainly the worst part, but it’s easy to distract myself until I reach 4:30pm.  Now, even that 1-2 hours is minimally disruptive now that I’ve adapted.

After a couple weeks, my body was so well-adapted, I don’t feel any difference at all comparing fasting days than non-fasting days.  I started doing 20-30 minutes of light-medium exercise in the morning, which feels completely normal.  It seems that once your body gets used to switching back and forth from ketosis, it does so easier and with less hunger when you need energy, even after exercising (and yes, the ketone strips are darker at 4:30pm on days when I exercise).

There are short periods of feeling mildly hungry throughout the day, but it has become a non-issue because (1) it is infrequent and mild, and (2) I’ve given myself the mindset that the such feelings are actually good, and should be savored.  It’s a sign that my body is doing some spring cleaning and consuming some fat.  Just convince yourself that the more you feel that sensation, the more your body is benefiting from this whole thing, clearing out old fat cells, etc.

Finally, dinner decisions are less stressful since I don’t have to be so careful of my calories within the window.   And I’ve found myself desiring less meat and more vegetables.  In the past, I’ve had a mindset that dinner is a big, hearty meal, and I’ll be unsatisfied unless I fill up on dense calories.   Now, dinner feels almost like another “snack” within my window, and I don’t feel it necessary to have a large, meaty meal.  I’ve actually been more open to vegetable-heavy dinners knowing that if I’m not full, I still have another couple hours until my eating window closes.  And that’s okay.


This is a long post, but the results are short.  I’ve been doing this 4-5 days per week for about 6 weeks now.  I’ve lost 8 lbs so far.  My work days feel clearer without eating decisions, and my evenings feel freer with less eating restraints.  I feel less guilty for having indulgence meals for dinner on occasion (primarily, pizza), yet also crave vegetable-heavy meals to make sure I’m getting nutrients.  I also don’t impact my family life much, because I don’t eat with them during the week, and my eating schedule is “normal” on the weekends when we are together.

Finally, WHM:  yes!  I have always liked doing the breathing in the afternoon, and now I definitely feel “purer” doing it on my totally empty stomach.  I don’t really track my breaths or retention times anymore, but on fasting days I almost always have a good session.  Even stretching is easier with an empty stomach!

Lastly, I’ve saved a ton of time and money!  This may not apply to everyone, but I used to go out (or order in) food for lunch all the time.  I don’t know how much I spent per week on it, but it’s a luxury I’ve always convinced myself I deserve.  Now, I spend exactly $0/week on lunch and zero minutes thinking about it.  Instead, I use what would be my lunch break to do WHM stuff or exercise.

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