What Is a Fasting Mimicking Diet? FMD Diet Plan, Benefits & Downsides

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Fasting mimicking diet - Dr. Axe

By Rachael Link, MS, RD

There’s a good chance that you’ve probably heard about the many health benefits of fasting, from lowering triglyceride levels to helping the pounds slide right off. But if the thought of going for long periods of time without eating doesn’t sound fun or appealing to you, you’re in luck. With a fasting mimicking diet, you can get many of the same benefits as fasting without skipping meals.

Research has begun to unearth many impressive benefits of the fasting mimicking diet, suggesting that it could help with everything from improved cognition to diabetes management. Best of all, the makers of this diet claim that it can all be done by simply limiting your intake five days a week, just one time per month.

Has your interest been piqued? Keep reading to learn more about the fasting mimicking diet and whether or not it may be right for you.

What Is a Fasting Mimicking Diet?

The fasting mimicking diet is a diet that involves severe caloric restriction for five days out of the month. It follows the same principle as fasting by temporarily depriving the body of food to take advantage of health benefits like increased fat burning and reduced inflammation.

But what is fasting? It can be hard to group all types of fasting into a single fasting definition. For example, some types of fasting restrict food consumption for entire days at a time while some limit it to just a few hours each day. Others, such as the Daniel fast or the bone broth fast, only allow the consumption of certain types of food or food groups.

The fasting mimicking diet follows the same principle but allows you to eat a small amount of food while still reaping the rewards of fasting.

How Does It Work?

Each cycle of the diet lasts for five days, and it can be repeated several times every month or every other month to help promote long-term health.

The diet relies on severe calorie restriction to imitate the effects of fasting. During the first day of the diet, calories are limited to 1,100 calories. Then for the remaining days of the diet, calories are cut even further, down to about 800 calories per day.

What you eat on the diet is just as important as the amount of calories. The diet is high in fat, with about 80 percent of calories coming from fat and 10 percent coming from fat and protein, respectively.

By essentially tricking your body into thinking it’s fasting, you are able to take advantage of the many health benefits of intermittent fasting.

Although studies on the effects of this diet are fairly limited, research has found that it could reduce the risk of disease, kick up fat burning and boost brain health.


What is a fasting mimicking diet? - Dr. Axe


Potential Fasting Mimicking Diet Benefits

1. Promotes Fat Loss

While the fasting mimicking diet comes with all kinds of benefits to heart health, many people begin this diet looking to slim down and shed some pounds.

In theory, it makes sense that this diet would spur weight loss, as it is low in calories and encourages the consumption of mostly nutrient-dense foods. Research has also confirmed that this diet could help decrease both body weight and body fat.

In a recent study published in the journal Science Translational Medicine, 100 participants followed either a fasting mimicking diet five days a week for three months or their usual diets. At the end of the study, the diet was found to decrease both total body fat and body mass index. (1)

2. Lowers Cholesterol

The fasting mimicking diet may help reduce several risk factors of heart disease, including cholesterol levels.

The 2017 study from the journal Science Translational Medicine mentioned above, for instance, showed that following the fasting mimicking diet for three months decreased levels of both total and bad LDL cholesterol in participants.

Additionally, this diet is high in fat and includes plenty of nuts and olives. These foods contain heart-healthy fats that can keep cholesterol levels in check and help prevent coronary heart disease.

Having too much cholesterol in your blood can cause plaque to build up in your arteries, which leads to the hardening and narrowing of the arteries. This forces your heart to work harder to pump blood and can increase the risk of heart disease. (2)

By pairing this diet with an overall healthy lifestyle, you can lower cholesterol levels naturally and keep your heart healthy.

3. Relieves Inflammation

Inflammation is a normal reaction by your immune system to protect your body from foreign invaders. When you get a bug bite or a pimple, for example, you might notice some redness and inflammation.

Chronic inflammation, however, can contribute to the development of several chronic diseases, including heart disease, diabetes, cancer and multiple sclerosis. (3)

The fasting-mimicking diet could aid in controlling inflammation and may help reduce the risk of chronic disease.

In one 2016 animal study, researchers demonstrated that a fasting mimicking diet could effectively prevent damage to the myelin sheath, which provides protection to the nerve fibers in the spinal cord and brain. It also reduced symptom severity by 20 percent, decreased several inflammatory markers and promoted the regeneration of the myelin sheath. (4)

Although more research is needed, the fasting mimicking diet could be beneficial in the treatment of multiple sclerosis, a condition in which the immune system attacks and causes damage to the myelin sheath.

4. May Help Reverse Diabetes

Research has produced some promising results on the potential effect of the fasting mimicking diet on diabetes. A recent animal study in Cell showed that the diet helped maintain normal blood sugar levels in mice and promoted the generation of insulin-producing beta cells. (5)

Insulin is a hormone responsible for transporting glucose (sugar) from the blood to the cells where it can be used as energy. Increasing insulin production can help keep blood sugar levels from rising too rapidly. Similarly, the previously mentioned Science Translational Medicine study found that following a fasting mimicking diet levels led to decreased blood sugar levels in participants.

In addition to following a fasting mimicking diet, regular exercise and a healthy lifestyle can also help reverse diabetes naturally.

5. Decreases Blood Pressure

Besides lowering blood cholesterol, following a fasting mimicking diet can also help support health by keeping your blood pressure in check. High blood pressure puts a strain on your heart and forces it to work harder, weakening the heart muscle and increasing the risk of developing heart disease.

Studies show that intermittent fasting benefits your blood pressure levels along with several other risk factors for heart disease. (6) Similarly, some studies have also found that a fasting mimicking diet can reduce blood pressure to help improve the health of your heart. For instance, it was found that following the diet for three months led to a significant reduction in blood pressure levels of participants.

To lower blood pressure even more, limit your intake of ultra-processed foods and foods that are high in sodium, get in plenty of physical activity, cut back on alcohol and smoking, and lose any extra pounds you might be hanging on to.

6. Improves Cognitive Health

Recent research has also uncovered some impressive benefits of the fasting mimicking diet on brain health and function.

In a 2015 animal study, mice were fed two cycles of a fasting mimicking diet each month. Not only did this improve cognitive performance, but it also promoted the regeneration of neurons in the brain and decreased markers of aging. (7)

Plus, this diet encourages the consumption of several brain-boosting foods and ingredients. Olive oil, for instance, has been shown to improve cognitive function, learning and memory in several human and animal studies. (8, 9, 10)


Fasting mimicking diet benefits - Dr. Axe


Potential FMD Diet Downsides

Despite the impressive benefits offered by the fasting mimicking diet, there are some important downsides that need to be considered.

First of all, this diet can be difficult to follow. Not only are you cutting your calorie intake in half (or more), but you’re also limited in the foods that you can eat as well as the amounts. It can be a real challenge to stick to, especially for five days at a time.

Additionally, exercise is prohibited on this diet. While this may be welcome news for those who avoid the gym at all costs, regular exercise is an important part of a healthy lifestyle. Repeating the cycles of this diet plan long term could lead to physical inactivity, which may come with adverse effects that nullify some of the benefits of the diet.

Lowering your caloric intake to 800–1,100 calories per day can also come with some pretty unpleasant side effects, such as fatigue, headaches and weakness.

Following this diet long term could also increase the likelihood of nutrient deficiencies as well, as the diet is high in fat but low in protein and carbohydrates and cuts out many nutrient-rich foods.

Plus, although the diet has been shown to be beneficial for diabetes, it could cause blood sugar levels to drop dangerously low and cause hypoglycemia, which could be harmful for those who have diabetes if not done under medical supervision.

How to Follow a Fasting Mimicking Diet

The fasting mimicking diet is made up of five days per cycle, which can be repeated once per month to see long-term results. For the first day, calories are slashed to 1,100 per day, and just 800 calories are allowed daily on subsequent days.

The diet is rich in nuts and olives to provide healthy fats. Other diet components include foods like vegetable soup or broth, puffed rice bars, nut bars, and tea.

Plant-based whole foods are emphasized on the diet along with minimal amounts of animal products. Carbohydrates should be from complex plant sources, and fats should be from healthy oils and nuts.

Alcohol is prohibited on the diet, and coffee intake should be limited to no more than one cup per day. Additionally, you should not exercise at all while doing this diet plan.

A typical fasting mimicking diet meal plan may include a handful of nuts with tea for breakfast, vegetable soup for lunch, olives as a snack and more soup for dinner.

It’s recommended to do one cycle of this diet per month for at least three months or even longer to help improve long-term health. Doing more than one cycle per month could lead to nutrient deficiencies and negative effects on health.


Fasting mimicking diet - Dr. Axe


FMD Recipes

Although pre-made and pre-portioned products are available for convenience and ease, it can be pretty pricey. For a five-day fast, for example, the Prolon diet cost hovers around $300.

However, you can try making some FMD-friendly, cost-effective recipes of your own. Here are a few of the fasting mimicking diet (FMD) recipes that you can try at home:

Fasting Mimicking Diet History

The fasting mimicking diet was created by Dr. Valter Longo, the director of the Longevity Institute at the University of Southern California. For the past 20 years, Dr. Longo has been researching ways to slow and reverse aging to prevent chronic disease.

He became interested in how fasting had an anti-aging, rejuvenating effect on the body as well as the effects of regimens like alternate day fasting.

However, because fasting can be associated with negative side effects and risks, he created a new diet plan of his own: the fasting mimicking diet.

Since the inception of the diet, a multitude of studies have been released demonstrating the potential benefits of short-term caloric restriction, and more interest has generated on the possible health effects of the fasting mimicking diet.


Doing multiple cycles of this diet per month could potentially lead to nutrient deficiencies long-term. Stick to just one cycle per month, and consult with a doctor or dietitian if you have concerns about meeting your nutritional needs.

Those with diabetes should consult with their doctors before beginning this diet as it may lead to low blood sugar. Additionally, blood sugar medications may need to be adjusted prior to starting to avoid adverse side effects.

If you have a history with eating disorders, this diet may encourage unhealthy behaviors and trigger symptoms. It is also not recommended for children or teens who may still be growing or those with a nut allergy, as nuts make up a substantial portion of the diet.

Although side effects like fatigue and weakness are to be expected due to the nature of this diet, always listen to your body and consider discontinuing or consulting your doctor if symptoms persist.

Final Thoughts

  • The fasting mimicking diet is a very-low calorie diet plan that restricts calories five days per week, one time per month.
  • It emphasizes plant-based, whole foods with limited animal products and lots of heart-healthy oils and nuts.
  • Although more research is needed, preliminary studies have found that the fasting mimicking diet plan could help decrease cholesterol, reverse diabetes, lower blood pressure, improve cognitive health, alleviate inflammation and amp up fat burning.
  • This diet may not be for everyone, though. It should be limited to once per month to avoid nutrient deficiencies and is not recommended for children and teens or those with a nut allergy. It may also cause negative side effects for diabetics and those with a history of eating disorders.
  • However, for many people, the fasting mimicking diet can be a good alternative to other fasting regimens and may help benefit health.

Read Next: Daniel Fast: Benefits for Your Spiritual, Emotional & Physical Health

Source: Dr Axe