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Home arrow Nutrition arrow Intermittent Fasting arrow Fasting Mimicking Diet: Everything You Need to Know

Fasting Mimicking Diet: Everything You Need to Know

Written by Edibel Quintero, RD
Fact checked by Rosmy Barrios, MD
Last update: October 17, 2023
8 min read 1392 Views 0 Comments
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Fasting mimicking diets offer a new way of fasting intermittently. While the overall concept is the same, some unique elements make the fasting mimicking diet an alternative option. How does it work, and what are its potential benefits and side effects?

fasting mimicking diet

Do hunger pangs leave you unable to carry on with an intermittent fast?

If yes, you’re not the only one. Lots of people find intermittent fasting, especially prolonged fasting, too uncomfortable to keep up with. Restricting your food intake for long hours can leave you feeling exhausted and hungry. Many people quit before acquiring the full benefits.

So, what if there was a way to reap the health benefits of intermittent fasting without completely eliminating calories?

Well, the fasting mimicking diet (FMD) is a newer form of intermittent fasting. While it still centers around calorie restriction, participants don’t have to forego food entirely. This can help mitigate some of the biggest hurdles that occur when you begin fasting intermittently.

Keep reading to learn all about the fasting mimicking diet.

Fasting Mimicking Diet: What Is It?

The fasting mimicking diet, also known as the ProLon Fasting Mimicking Diet, is a modified form of intermittent fasting created by Italian-American biologist Dr. Valter Longo. The fasting mimicking concept mimics the health benefits of intermittent fasting without the harsh restrictions that cause many people to quit a fast.

Fasting mimicking essentially tricks the human body into thinking it is in the fasted state without completely cutting out calories. It still focuses on controlled calorie restriction but allows participants to get essential nutrients from specific whole, plant-based foods.

This helps mitigate certain intermittent fasting side effects, such as hunger pangs, fatigue, and headaches.

This is a weight loss program with a five-day eating plan. It comes with a meal kit featuring pre-packaged foods for the participant to consume. These meals are high in healthy fats and low in carbohydrates and proteins.

Does Fasting Mimicking Work?

It is not completely clear whether the fasting mimicking diet works. More research is necessary to conclude whether this modified form of time-restricted eating delivers the same health outcomes as the more popular IF eating pattern or other forms of restrictive eating.

So far, the research suggests that the fasting mimicking diet can reduce body weight, total body fat, systolic blood pressure, and insulin-like growth factor. These results were present in clinical trials over three FMD cycles. It may also reduce risk factors for age-related diseases.

Is the Fasting Mimicking Diet Healthy?

Intermittent fasting is a healthy and safe weight loss method for most people. It can improve health in multiple ways, boasting benefits for healthy aging, enhanced cognitive performance, and improved metabolic health. The fasting mimicking diet proposes similar health benefits.

As you can still consume important nutrients, the fasting mimicking diet could potentially be more healthful than original time-restricted diets. It allows you to consume a portion of your normal caloric intake, decreasing the amount of stress that fasting puts your body under.

Fasting Mimicking Diet vs. Intermittent Fasting

The fasting mimicking diet is a form of intermittent fasting, but the two differ in several ways. The best strategy for you depends on your personal goals and preferences. It’s essential to recognize the features of each dietary pattern before getting started.

The table below shows the key differences between intermittent fasting and the fasting mimicking diet. 

Fasting mimicking dietIntermittent fasting 
Diet’s key featuresPromotes the benefits of intermittent fasting without complete food abstinence.

Participants can eat small amounts of specific low-calorie, low-carb, and low-protein foods.

A five-day-long meal plan that delivers vital nutrients while keeping the body in a fasted state.
Meal timing schedules that cycle between fasting and eating over a specific amount of time.

Focuses on when you eat rather than what you eat.
ProsAllows you to get essential nutrients.

Allows you to eat a low-calorie diet
Meal kit includes lots of healthy, plant-based ingredients.

Side effects may be less severe than intermittent fasting.

May reduce hunger pangs and sugar cravings.
Lots of human research to support intermittent fasting health claims.

Scientifically proven to promote fat loss.

A versatile diet plan as there are multiple fasting diets to choose from to suit your lifestyle.
ConsNot as much human research.

The ProLon meal kit is expensive.

You must follow the plan for five consecutive days.

Participants may struggle to adapt to significant calorie restrictions.
Difficult to sustain, especially for prolonged periods.

Several side effects, including hunger, headaches, fatigue, digestive issues, and nausea.

May cause nutritional deficiencies.

What Do You Eat on a Fasting Mimicking Diet?

The ProLon Fasting Mimicking Diet is a five-day meal kit of all-vegetarian, plant-based ingredients. You eat one box daily and follow the instructions with the kit, so you know what to eat and when. Each box includes foods for breakfast, lunch, dinner, and snacks.

The five-day fasting box includes various packaged items, including herbal teas, kale crackers, nut bars, olives, soup blends, and vegetarian supplements. All foods are non-GMO, gluten-free, and lactose-free. The calorie percentages are tailored to each day, allowing you to reduce calories gradually.

The boxes are purposefully designed to be taken accordingly. It is essential to follow the directions to ensure you eat the right foods in the correct order. Doing so enables you to trick your body into fat-burning mode and begin your weight loss journey without eliminating food.

How Long Do You Have to Follow the Fasting Mimicking Plan?

The fasting mimicking diet is five days long. You can choose any five days of the week, but they must be consecutive. It is intended that you follow this diet plan once a month for three straight months.

According to ProLon, from day one, the body begins transitioning into fat-burning mode. Over the course of the five days, fat burning increases, and the body initiates autophagy – the natural process of cleaning up old and damaged cells.

After the first three FMD cycles, ProLon suggests partaking in the program occasionally throughout a one-year period when you want the health benefits of fasting. For example, you could try the periodic diet again after six months to boost your weight loss progress.

What Are the Benefits of the Fasting Mimicking Diet?

A fasting mimicking diet has many purported health benefits. Most research focuses on intermittent fasting benefits rather than fasting mimicking. However, this diet tends to replicate the effects of fasting and, therefore, delivers similar results.

Let’s take a look at some possible health outcomes:

#1 Promotes weight loss

The fasting mimicking diet promotes weight loss by significantly reducing daily caloric intake. Those following the FMD regime tend to consume around 34–54% of their usual calories. Calorie restriction helps people lose weight by achieving a calorie deficit.

Moreover, FMD reduces carbohydrate intake, eliminating the body’s primary fuel source. When you deprive the human body of carbohydrates, it must find energy elsewhere. It begins to metabolize body fat to fuel your system and triggers ketone production.

Ketones are an alternative energy source produced when the liver breaks down fats. The ketogenic diet is a proven weight loss method because it pushes the body into ketosis. Following the fasting mimicking diet can speed up ketosis and help you burn fat faster.

Furthermore, animal studies show monthly FMD cycles can reduce obesity by decreasing visceral and subcutaneous fat without reducing lean body mass. Visceral fat, which wraps around the organs, is particularly dangerous and is associated with cardiometabolic risk.

#2 May improve blood glucose control

A fasting mimicking diet with certain meal replacement foods can reduce body weight and improve metabolic syndrome in people with type 2 diabetes. It may improve blood glucose and lipids while promoting lasting blood sugar control.

FMD may also be effective for reducing insulin resistance in people with obesity. The results appear promising, but more clinical research is required to review the role of fasting-mimicking and fasting diets in treating and managing type 2 diabetes.

#3 May reduce the risk of cardiovascular disease

The fasting mimicking diet may have beneficial effects on risk factors for cardiovascular disease and other cardiometabolic diseases. The dietary strategy can help reduce plasma levels of TMAO (trimethylamine N‐oxide) – a biomarker for cardiovascular and metabolic disease induced by diet.

Additionally, intermittent fasting diets can promote heart health. For instance, they can help reduce hypertension – a predominant risk factor for cardiovascular disease.

#4 May aid the prevention of autoimmune diseases

Fasting mimicking diets, and other dietary interventions can be beneficial for preventing autoimmune diseases. Long-term fasting and FMD cycles appear to have anti-aging and anti-inflammatory effects that may help reverse certain autoimmune disorders.

The results may occur from the body replacing old, damaged cells with healthier, functional cells. Furthermore, reducing inflammation can contribute to the prevention and treatment of autoimmune disorders. For example, FMD reduced multiple sclerosis symptoms in mice by reducing inflammatory markers.

The dietary pattern might benefit people with inflammatory arthritis, including rheumatoid arthritis. Again, more human trials are needed before the FMD can be recommended as an effective treatment option.

#5 Supports gut health

An unhappy gut can cause various problems. The composition of the gut bacteria plays a crucial role in human health and disease. An imbalance can cause the development of several chronic diseases, including irritable bowel disease (IBD), obesity, and diabetes.

This diet can boost gut health by reducing intestinal inflammation, increasing stem cells, and stimulating healthy gut microbiota. Due to these anti-inflammatory effects, FMD is likely to impact inflammatory bowel diseases positively.

This eating pattern may help reduce symptoms and promote the regeneration and recovery of damaged cells in the gastrointestinal tract.

Side Effects of the Fasting Mimicking Diet

There can be side effects of caloric restriction and fasting diets. Although the fasting mimicking diet claims to mitigate the common symptoms that result from fasting, it’s still possible for people to experience adverse effects from slashing their regular caloric intake.

Side effects can be temporary as your body adapts and may include:

  • Feeling hungry
  • Sugar cravings
  • Headache
  • Fatigue
  • Dizziness
  • Weakness

The fasting mimicking diet is suitable for most healthy adults, but those with health conditions should discuss the diet with a doctor or health coach to assess the benefits and risks.

Calorie-restrictive diets are not recommended for people with eating disorders or those who have had an eating disorder in the past. The ProLon diet is not recommended for people with certain health problems, those who are underweight, or pregnant and lactating women.

A Word From MD

Fasting is the ancient practice of voluntary or obligatory food abstinence.

Restricting your food intake for a specific period has many wellness benefits. People voluntarily fast for numerous health reasons. Primarily, people practice fasting for weight loss, mental clarity, improved cognitive performance, disease prevention, and a healthy lifespan.

The mimicking diets are designed to imitate metabolic processes that occur during fasting while managing hunger and cravings. With the fasting mimicking diet plan, the idea is that you can enjoy delicious food while promoting weight loss and preserving muscle mass.

In theory, fasting mimicking works by simulating the metabolic shift that occurs when the body is deprived of food. In this fasted state, the body moves from burning glucose as its main fuel source to burning body fat. It is this transition that makes fasting great for weight loss.

Many people couple intermittent fasting with the keto diet to speed up ketosis. However, the fasting mimicking diet is not entirely keto-friendly. Fortunately, with a few tweaks, you can create a DIY fasting-mimicking diet that matches the keto diet’s requirements.


The fasting mimicking diet is a restrictive, low-calorie eating program created to help people benefit from fasting intermittently without suffering the challenges that food abstinence brings. It claims to deliver the same potential benefits as traditional intermittent fasting.

FMD may help individuals lose weight, burn body fat, boost brain function, and regulate blood pressure and blood glucose levels. However, more human studies are necessary. Like any diet, getting professional medical advice first is vital, especially if you have any health conditions.

Written by Edibel Quintero, RD
Edibel Quintero is a medical doctor who graduated in 2013 from the University of Zulia and has been working in her profession since then. She specializes in obesity and nutrition, physical rehabilitation, sports massage and post-operative rehabilitation. Edibel’s goal is to help people live healthier lives by educating them about food, exercise, mental wellness and other lifestyle choices that can improve their quality of life.
The article was fact checked by Rosmy Barrios, MD
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