A fast-mimicking, or fasting-mimicking, diet copies fasting’s effects while allowing small portions of food. Fasting is going without food or beverages for a certain period. Fasting is believed to offer many health benefits, such as weight loss, decreased inflammation, and improved blood sugar management.
However, a fasting-mimicking diet is not ideal for everyone and shouldn’t be done by those with certain medical conditions or who are pregnant or lactating.
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How the 5-Day Fast Works
A fasting-mimicking diet can last four to seven days and may be repeated once every few weeks or months. Unlike traditional fasting or intermittent fasting (periods of fasting that alternate with periods of eating), eating some food is allowed on a fasting-mimicking diet.
The fasting-mimicking diet is a plant-based diet that is low in protein and carbohydrates but high in fat. Sticking to the amount of calories and macronutrient (carbohydrates, protein, and fat) ratios is important to help reach the fasting state and reap the benefits of fasting.
The exact number of calories and subsequent macronutrient goals will vary from person to person, depending on your normal intake.
On the first day of the fast, you will consume more calories than the remaining four days. A five-day fasting-mimicking diet typically goes as follows:
- Day 1: You consume about 55% of your normal calorie intake. A common recommendation for macronutrient percentage breakdown is to roughly have 34% calories from carbohydrates, 10% from protein, and 56% from fat.
- Days 2 through 5: You consume about 35% of your normal calorie intake. Commonly recommended macronutrient percentages are around 47% carbohydrates, 9% protein, and 44% fat.
What to Eat
Because the fasting-mimicking diet is plant-based, allowed foods include:
- Fruitssuch as berries, apples, peaches, plums, cherries, and oranges
- Healthy fatssuch as olive oil, avocados, nuts, and seeds
- Plant-based proteinsuch as beans, lentils, and other legumes
- Vegetablessuch as broccoli, carrots, asparagus, zucchini, leafy greens, tomatoes, peppers, and onions
- Whole grainssuch as whole wheat bread, quinoa, brown rice, and barley
It’s also important to stay hydrated by drinking plenty of water daily. Non-caffeinated herbal teas are also allowed. Some fasting-mimicking diets allow for one cup of black coffee per day.
What to Avoid
Stick to a plant-based and anti-inflammatory diet while on the fasting-mimicking diet. This includes avoiding:
- Alcohol
- Animal fatssuch as butter, lard, and ghee
- Animal proteinsuch as beef, pork, poultry, and fish
- Dairy productssuch as milk, yogurt, and cottage cheese
- High-starch foodssuch as potatoes, white rice, and pasta
- Sugar-sweetened beveragessuch as soda, juices, punch, lemonades, energy drinks, sports drinks, and flavored or sweetened coffee drinks
- Sugary foodssuch as cookies, cakes, ice cream, pastries, donuts, and other desserts and treats
Potential Benefits
The fasting-mimicking diet has many potential health benefits, similar to other fasting diets. These include:
More studies are needed to fully understand and confirm the long-term benefits of a fasting-mimicking diet.
Potential Side Effects
While there are potential benefits of a fasting mimicking diet, there are also some potential side effects. These include:
Is the FMD Diet Right for You?
While generally considered safe, a fasting-mimicking diet is not appropriate for:
- People who are pregnant or lactating
- People who are underweight or have nutritional deficiencies
- People with a history of eating disorders
- Children under 18 years old or adults over 70 years old
- People currently engaging in strenuous physical activities
If you have underlying medical conditions, such as diabetes, or are taking medications, talk with a healthcare provider to see if a fasting-mimicking diet is appropriate for you.
Other Types of Fasting to Consider
There are various types of fasting, all of which have similar health benefits.
One of the most popular types of fasting is intermittent fasting. There are several different types of intermittent fasting, such as overnight, alternate-day, and time-restricted fasting. This makes intermittent fasting a more flexible option, allowing more people to try a fasting diet.
These fasts are ideal for busy individuals seeking a more flexible fasting schedule who want to lose weight and improve their health.
Water fasting is a fast in which you do not consume anything besides water. This type of fast typically does not last longer than 24 to 72 hours and is not appropriate for many people with underlying medical conditions or who take medications.
Juice fasting consists of consuming only fruit or vegetable juices for a few days to weeks.
Summary
A fast-mimicking, or fasting-mimicking, diet is a modified version of fasting that allows for some calories during the fasting period. It follows a plant-based eating pattern that is high in fat while being low in protein, carbohydrates, and daily caloric intake. Allowed foods include vegetables, fruits, and plant-based foods with healthy fats. Foods to be avoided include animal-based products, sugary foods, and high-starch foods like pasta.
There are both potential health benefits of a fasting-mimicking diet, as well as side effects. While generally considered safe, a fasting-mimicking diet is not appropriate for certain people. Consult a healthcare provider before trying it.
