How To Do A Fast Mimicking Diet - Our Clean Food Fast

Fast mimicking essentially “tricks” our bodies by reducing calories enough to feel as if they’re fasting so they can reap these benefits.

Getting Started

Most research on fast mimicking shows the best results after about five days and/or when your ketosis sets but doing it anywhere between 3-7 days is beneficial. It’s also intended to be repeated at least twice per year, or as often as once a month, to get enough benefits from it depending on your health.


You might also want to measure certain biomarkers if you’re interested in tracking your fasting outcomes. This could be doing lab tests before and after the fast as well as measuring blood glucose and ketones each day and weight changes.

Also, you might want to set up your environment for the fast:

  • Tell friends and family you see during this time what you’re doing and why it’s important you have support. We use a closed Facebook page that everyone gets an invitation and can post encouragement and questions
  • Clean out the pantry and fridge Get rid of any snack foods at home or work that might tempt you.
  • Plan to give yourself more time for sleep, since you’ll likely be more tired than usual.
  • Plan for some physical activity each day, but only light stuff. Avoid intense exercise during this time.


Fast Mimicking Basics

Some people find easing into the fast helps by eating slightly higher calories the first day, around 50% of total intake. This is then reduced to around 35-40% of total caloric intake for the rest of the days. You also want the things you do consume to be easily digestible and in very small amounts.

One popular pre-packaged fast mimicking diet, called ProLon, contains all five days’ worth of food for the fast in sachet form. We elected to have whole food  prepared by a Commercial Kitchen. The food is all plant-based , in soups and bars. So basically a day looks like tea and a nut bar for breakfast, a small amount of vegetable soup and a few seaweed crackers for lunch, a few olives in the afternoon, and another small portion of soup for dinner.

You don’t need a pre-packaged box to do a fast mimicking diet, though—especially if you want to keep the diet and to the calorie percentages and considered how you’ll space them out each day. You need to plan out all the food for the entire fast so there’s nothing else to worry about. So this is where the prepacked Clean food fasting started.


Macros for traditional fast mimicking are 34% carbs, 10% protein, and 56% fat for the first day and 47% carbs, 9% protein, and 44% fat for the remaining days. This is obviously different if you’re following a ketogenic diet, which we’ll go into further below.

Black coffee and tea (a cup per day) are typically allowed, although not necessary—and make sure they don’t contain any added creams or sugars (coconut oil is okay if you factor it into macros).

Note that those with health issues should consult with their medical practitioner before doing a fast mimicking diet at home.

It’s also important to supplement the fast to ensure you receive important nutrients and electrolytes. See our ideas below.


Supportive Supplements

Taking supportive supplements helps ease into the fast, as well as provide enough nutrition throughout. Those might include:

  • Electrolytes like magnesium and salt to replenish any loss through water loss and supports regular bowel function
  • Compounded multivitamin to provide micronutrient support
  • Branch chain amino acids (BCAAs) to help prevent any loss of lean muscle
  • Algal oil or cod liver oil for omega 3s


Fast Mimicking and Ketosis adaptation

Fast mimicking is a great preface to a ketogenic diet. That’s because it can help you get into ketosis faster. Plus, eating keto foods helps you stay in ketosis the whole time.

With ketogenic fast mimicking, you’ll want to keep your macros within the proper range of 5-10% carbs, 20-25% protein, and 70-80% fat. This is harder and compliance would be more challenging.