What Is Bulletproof Protein Fasting? Why You Should Protein Fast Weekly

By: Dave Asprey
July 5, 2019

What Is Bulletproof Protein Fasting? Why You Should Protein Fast Weekly

Bulletproof Protein Fasting is one of the most potent, but underutilized tools in the Bulletproof toolbox.

In a nutshell, protein fasting can help reduce inflammation and kick start fat loss. One day per week, you limit your protein to 15 grams or less per day. To keep you full and energized, consume a cup of protein-free Bulletproof Coffee in the morning and have near-zero protein, high fats and moderate carbs throughout the day. For optimal results, eat your carbohydrates in the late afternoon and evening.

Easy, right?

Instantly download the Bulletproof Diet Roadmap and take the guesswork out of what to eat, when to eat and when to fast. 

Why you should do a protein fast at least once a week


You may be wondering why protein fasting is a good idea. Here are some of the benefits and the science behind protein fasting.

By protein fasting once a week, you are essentially allowing your body a full day to use its digestive machinery to perform self-maintenance. This process is called autophagy—or, literally translated, self-digestion.

Autophagy is the way your body cleans up damaged cells in order to regenerate new, healthier cells. Cleaning out the clutter helps keep you young.

The main way to induce autophagy is through intermittent fasting. You can also induce it by dramatically lowering your protein intake once a week. If you’re already intermittent fasting, you’re turbocharging your cellular cleanup processes.

Protein fasting ramps up “cleanup mode” in your cells

Over time, cells accumulate dead organelles, damaged proteins and oxidized particles that interfere with cell function and accelerate aging. Autophagy is the body’s natural cleaning process. It recycles the junk in your cells and turns it into energy.

Essentially, autophagy is like a trash incinerator for your cells, and protein fasting turns up the heat. In order you look and feel your best, you want to support autophagy—and protein fasting helps you get there.

Does protein fasting interfere with muscle mass?

You may be concerned about muscle catabolism, which is when your body gets its protein requirements from your skeletal muscles. Understandable—you don’t want to negate all of your progress at the gym.

Not only does protein fasting not interfere with building muscle, but it can also benefit your muscles. Autophagy is required to maintain muscle mass.[1]

If you are interested in staying younger and building muscle by spending less time working out (and who isn’t?), it makes sense to trigger autophagy.

Let’s look at the two main signals for the body to turn on autophagy. The first is fasting.[2] This is one of the reasons you’ll see such amazing results with Bulletproof Intermittent Fasting as well.

It turns out there’s an even better way to turn on autophagy, and that’s by occasionally limiting protein consumption. When you do this, you force your cells to find every possible way to recycle proteins. In their search, they bind and excrete toxins that were lurking in your cell’s cytoplasm, the gel-like substance enclosed within the cell membrane.[3] It’s like taking your car to the car wash and having it deep cleaned.

Studies have shown a number of additional benefits to being protein deficient that are similar to the benefits of fasting. The first is that protein deficiency lowers insulin and mTOR.[4][5]

Remember, stomping down mTOR so its secretion can spring back up is key to building muscle.  When I spent almost a year as a raw vegan, which automatically limited protein, it turns out it caused many health problems. In fact, being chronically protein deficient is awful for your brain and your body.

The trick is to become temporarily protein deficient. The simplest way to do this is to do a traditional fast and eat nothing for 24 hours or longer; however, because eating nothing for 24-48 hours is inconvenient if you have a job or friends, there is an easy hack for this.  If you want to experience the benefits without all that fun in a cave, Bulletproof Protein Fasting does the trick.

When I first started experimenting with this a couple of years ago, I limited my protein to no more than 25 grams —but I soon found out you get better results with even less.  Then a good friend and fellow biohacker named Josh Whiton told me to aim for 15 grams or less instead of 25 and to be more rigorous in my counting. Indeed, when I switched to a strict 15 grams a day, I felt a huge difference and had a visible reduction in my abdominal inflammation and muffin top.

The magic number probably varies depending upon your activity level and personal variation, but you might as well try to go as low as you can get.

Why protein fasting isn’t super intuitive

It turns out you might think you are protein fasting if you aren’t. This is most likely for one of three reasons:

  1. You are eating foods you don’t realize contain protein because we don’t think of them as typical high protein sources. What, broccoli has a little protein in it?
  2. By law, the government allows companies to label anything with less than one gram of protein per serving as having zero grams.  Even if you are reading labels closely, you won’t know if you are getting a few grams of protein if you eat five times the normal serving.
  3. You aren’t sure what a protein-free day of eating might look like or how to count/measure in grams (read below for easy solutions to these problems).

Should Anyone NOT Protein Fast? What Adjustments Can I Make?

Like Bulletproof Intermittent Fasting, Bulletproof Protein Fasting is not an all-or-nothing deal. Play around with what works for you. This may not be for everyone—there’s no data about doing this while pregnant, but it doesn’t sound like a great idea.

You can adjust the total amount of protein you’re eating on the day of your Bulletproof Protein Fast. This is another great opportunity experiment in order to get optimal results. I tried eating only protein at dinner, but didn’t get much of the slimming effect, so I either do it right—for a full day at 15 grams of protein or less—or I just don’t do it.

Bulletproof Protein Fast: Sample Meal Plans and Protocol

Here’s a sample shopping list to stock up on in preparation for your big day of protein fasting:

The following sample meals will help your body detox even more efficiently while giving you an extra boost of energy.

1. Bulletproof Protein Fast Breakfast

Protocol: Choose one to have as soon as you get up or whenever you are accustomed to eating breakfast.

  • Bulletproof Coffee (without any added protein)
  • Green tea blended with butter and Brain Octane (not as powerful as Bulletproof Coffee, however!)

2. Bulletproof Protein Fast Lunch

Protocol: Choose one to be eaten 15 to 18 hours after last night’s dinner.

  • Guacamole with cucumber and/or celery sticks
  • Sweet potato-ginger soup
  • Iceberg salad with baked carrot fries

3. Bulletproof Protein Fast Dinner

Protocol: Choose one to be eaten 5 to 6 hours after lunch.

  • Iceberg salad with buttered white rice
  • Carrot-Fennel soup with white rice
  • Baked Sweet Potatoes with guacamole

4. Bulletproof Protein Fast Dessert (optional)

Protocol: To be eaten soon after dinner.

  • Bulletproof Berry Bowl: Combine blueberries, raspberries, and strawberries with a squeeze of lemon juice and sprinkling of fresh chopped basil—enjoy!

How To Support Your Protein Fast

Remember, your goal is to stay below 15 grams of protein total during your one protein fasting day each week. Some people find it hard to count to 15, or tell me they are too lazy to do so, so here are my favorite tips:

1. Google It

If you want to eat something and you aren’t sure if it has protein in it, I highly recommend the ancient tip I like to call Google. You can simply type in “how much protein is in broccoli” or “protein in avocado” (or whatever you are trying to find out) to get an approximate measurement.

2. Buy a digital kitchen scale

By purchasing a small kitchen scale, you’ll be able to measure out your portions quickly and easily, which is useful for all Bulletproof recipes whether it’s protein fasting day or not.

3. Re-feed on Bulletproof carbs

Keep in mind this is not a cheat day. Do not give yourself permission to hit up all of your local fast-food joints and then eat an entire cake! Bulletproof Protein Fasting is simply a great way to get an even better reduction in inflammation and superior results. Call it a cheat day if you want—but only in that not eating enough carbs will cheat your body out of what it needs to burn fat and rejuvenate its detox systems!

Like I always say: If you’re hungry two hours later after a meal, you aren’t eating right. This guideline applies on all days of the week, even protein fasting day.

The meal ideas above are just a quick sampling of the types of foods you can eat while protein fasting. Find more recipes ideas on the Bulletproof Recipes page.

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