Assuming you’ve been keeping up with the series, you should be saying to yourself “Hey, maybe this fasting thing would be a cool thing to try out, and it might even make me healthier/live longer/lean out/lose weight/etc.,” which is a sufficiently extensive list of benefits, don’t you think? I could probably go on theorizing and speculating about all the reasons why you should consider intermittent fasting, but I’d rather move on to the implementation. Thinking about fasting, reading about fasting, and reciting the benefits of fasting are all pointless if you don’t know how to go about doing it.
First, let’s go over the different variations of fasting. I’ll give a quick rundown. Each involves not eating for a period of time, unsurprisingly.
A couple other rules that apply to all the given methods:
Sleeping hours (provided you don’t sleep-eat) count as fasting hours.
Eat well regardless. While some fasting plans tout their adherents’ ability to eat crappy food and still lose weight, I’m not interested in fasting solely as a weight loss method.
Okay, on to the variations.
Martin Berkhan’s incredibly popular fasting protocol is slightly more involved than others, but still pretty simple:
A daily 16 hour fast (Martin sometimes recommends 14 for women, who just seem to do better on shorter fasts) during which you eat nothing. Coffee, tea, and other non-caloric fluids are fine.
A daily 8 hour (or 10 for women) eating window.
Three days of weight training, ideally performed at the tail end of the fasting period. To improve performance and muscle protein synthesis, you have the option of consuming 10 grams of branched chain amino acids 10 minutes before the workout.
On rest days, eat more fat, fewer carbs, and slightly reduce calories.
Most people begin their fast after dinner (say, 9 PM), workout in the afternoon (at around 12 PM), and break their fast immediately post-workout (at around 1 PM), but you can use any schedule you prefer.
Your post-workout meal should have about 50% of your day’s caloric allotment (a real feast).
Who should try it?
Because it’s geared toward people interested in losing fat and putting on muscle and strength, Leangains presupposes that you will also be lifting heavy things several times a week, usually in the fasted state. Therefore, Leangains is best-suited for people who will be training on a regular basis. In fact, it’s probably the most meticulously-designed IF program.
People with steady schedules will have more success than people with erratic schedules. A huge part of Leangains is the hormonal entrainment induced by regular feeding times. Once you get locked into your routine, your hunger hormones will adapt to the schedule, and the fasting should get easier, or even effortless.
Start your fast in the morning, at lunch, or at dinner. It doesn’t matter as long as you don’t eat for 24 hours.
Break your fast with a “normal-sized meal.” Don’t try to make up for the lost calories by feasting.
Who should try it?
People interesting in fasting for the therapeutic benefits (cancer protection, autophagy, life extension, etc.) would probably get a lot out of this method, as opposed to people interested in the body composition benefits.
Going a full 24 hours without food is a much tougher slog than going for 16 hours. In my experience, going lower-carb and higher-fat makes longer fasts easier, so I’d have to say a low-carb Primal eater would do better than most.
The Warrior Diet
Ori Hofmekler’s plan is based on the feast-and-fast concept:
Eat one meal a day, at night, and make it a big one. A real feast. You have three or four hours to eat until full. So it’s basically 20/4 hours.
You can occasionally snack on low-calorie raw fruit and vegetables during the day, but try to limit protein as much as possible until the feast.
Exercise during the day, in a fasted state.
Who should try it?
People who have trouble sticking to a stricter fast will do better on the Warrior Diet, as it allows light eating during the time leading up to the feast, but I wonder if you’d be squandering some of the benefits by eating.
Alternate Day Fasting
Researchers often use this method in lab studies:
Eat normally one day (last meal at, say, 9 PM Monday).
Don’t eat the next day.
Resume eating the day after that (at, say, 9 AM Wednesday).
It works out to a 36-ish hour fast, although there’s plenty of wiggle room. You could eat at 10 PM Monday and break the fast at 6 AM Wednesday for a “mere” 32 hour fast.
Who should try it?
People who have no trouble going to bed hungry. With Leangains, Eat Stop Eat, and the Warrior Diet methods, you can always manage to get to bed with a full belly; with ADF, you will be going to bed on an empty stomach several times a week. That can be tough.
That said, the therapeutic benefits to serious conditions will most likely really be pronounced with this way of fasting. The casual 20-something Primal eater who lifts heavy things and enjoys going out with friends? Probably not ideal. The older Primal eater interested in generating some autophagy and maybe staving off neurodegeneration? It might just work out. And while I’m not able to tell a cancer patient undergoing chemotherapy what to do, I’d guess that the longer fasts will be more beneficial in that regard, too.
But my personal favorite way of implementing fasting?
Eat WHEN – When Hunger Ensues Naturally
I’m not going to put any bullet points here, because none are required. Instead, I’ll give a few scenarios:
I wake up bright and early on a Saturday morning. It’s about 65 degrees, the sun’s out, Buddha’s walking around with the leash in his mouth, and Red Rock Canyon is kinda calling my name. I’ve got my coffee already and I’m actually not all that hungry from dinner. You know what? I’ll go on that hike, skip breakfast, and really work up an appetite for lunch. Or not. If I’m hungry afterwards, I’ll eat. It’s a fast, but not really.
I hit the gym, put in a light workout, then swing by the beach for some sand sprints. I’m toast by the end and have to stagger back to my car, but I’m not hungry. Even when I get home and smell the grilled salmon, I have no desire for it. I might eat later that night, but only if my appetite returns. I’m fasting post-workout only because it doesn’t occur to me to eat, not because I’m following a plan.
I’m away on business, stuck on a layover that’s turned into a delay that’s turned into an overnighter. The only food available is a Kudos candy bar – I mean, healthy granola bar (they seriously still make these?) from the mini fridge, a greasy pizza joint on the corner across the street from the hotel, a Chinese takeout place next to the pizza joint, and a slew of fast food restaurants some ways down the road. It’s late, I’m tired, I had a Big Ass Salad before I left for LAX… you know what? I’m just going to skip the “meal.” I’ll figure out something at the airport in the morning (20 hour fast) or once I land (24 hour fast). And I’ll be okay either way.
That’s eating When Hunger Ensues Naturally.
This is the most natural, most effortless way of “fasting,” at least for me, because it allows a person to eat intuitively. Although most people will eventually acclimate to more regimented fasting schedules, and many may even need and thrive with that structure, I prefer a more fractal, loose, random pattern of “missing” (in quotations because I don’t feel like I’m missing anything, and that’s the whole point!) meals. I have no data on whether it’s as effective or more effective than the more popular methods, but I do know that I’ll often fast for 16 hours and eat for eight, or skip an entire day of eating, or sometimes (but very, very rarely) even approach a full 30 hours, and it seems likely that this random pattern of eating characterized the eating “schedules” of our ancestors.
In short, we’re all doing the same thing, chasing the same goals. We’re all skipping meals, reducing calories, staying active, and all the while we’re doing this without feeling miserable and restricted. It just so happens that because we’re efficient Primal fat-burning beasts, switching over to burning our own body fat reserves for energy during a fast is a natural, seamless transition. We often don’t even notice it. There’s no effort involved.
That’s the key: lack of stress. If any or all of these fasting methods stress you out, make you irritable, kill your performance, make you feel restricted, or reduce your ability to enjoy life, and these feelings persist beyond the first five fasts you attempt (when some adaptation difficulties are totally expected), you shouldn’t employ them. You should shelve fasting for a while and come back to it later, or never. It’s not a “requirement” or anything. It’s just a tool you can wield if your situation warrants it. In fact, this is the perfect opportunity to conduct an informal experiment of one. Try Leangains for a week or two, then throw in a full 24 hour fast once or twice a week for a bit, then try the WHEN method. Compare and contrast. How did you feel? How did you perform at work, at home, and in the gym? Take some waist measurements perhaps, or analyze your favorite barometer of body composition to see how the different fasting methods worked – or didn’t work – for you.
Now, I’d like to hear from you. What’s your favorite fasting method? Do you have one, or you just kinda go with the flow? Be sure to review the previous installments below and if you have any questions about any of the stuff I’ve covered in this series, leave them in the comment section and I’ll try to get them answered for you next week. Thanks for reading!
Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.