What is the 7 day fasting mimicking diet?

Research shows that cycles of a fasting-mimicking diet (FMD) can reduce risk factors for chronic diseases and promote cellular rejuvenation. A 7 day fasting mimicking diet is a structured, periodic plan that restricts calories and specific nutrients to trigger the body's fasting-like physiological responses.

Quick Summary

The 7 day fasting mimicking diet is a low-calorie, plant-based regimen that induces ketosis and cellular repair while still allowing for some food intake each day.

Key Points

• Mimics Fasting: The 7 day fasting mimicking diet (FMD) uses a low-calorie, plant-based meal plan to trick the body into a fasting state without full food abstinence.

• Promotes Cellular Repair: A primary benefit of the FMD is the induction of autophagy, the body's process for cleaning out damaged cells and regenerating new ones.

• Triggers Metabolic Switch: Restricting carbohydrates and calories pushes the body into ketosis, where it burns fat for energy instead of glucose.

• Leads to Health Markers Improvement: Cycles of the FMD have been shown to improve metabolic health markers like blood pressure, cholesterol, and insulin sensitivity.

• Requires Medical Guidance: Due to the restrictive nature and potential risks, it is critical to consult a doctor before starting the FMD, especially for a 7-day cycle.

What is the Fasting Mimicking Diet?

Developed by researchers at the University of Southern California (USC) Longevity Institute, the Fasting Mimicking Diet (FMD) is a short-term, low-calorie, plant-based eating plan. Unlike a traditional water-only fast, which involves consuming no food for an extended period, the FMD provides a specific, measured amount of nutrient-rich foods over several days. The goal is to deceive the body into thinking it is fasting, allowing it to reap the metabolic and cellular benefits of a prolonged fast without the extreme hunger or deprivation. The FMD typically lasts between four and seven days and is intended to be repeated in cycles, not followed long-term.

The physiological science behind the FMD

The core mechanism of the FMD involves shifting the body's primary energy source. When you consume significantly fewer calories and carbohydrates, your body depletes its glucose stores. Around day two of the diet, this prompts a metabolic switch, and your body begins breaking down stored fat for energy, producing ketone bodies. This state is known as ketogenesis. Beyond simply burning fat for fuel, the FMD also triggers a process called autophagy, which means "self-eating". Autophagy is the body's natural process of clearing out damaged or dysfunctional cells and cellular components, making way for newer, healthier ones. This cellular rejuvenation is one of the key benefits associated with the FMD and is what many longevity researchers find most promising. By carefully controlling the macronutrient ratio—typically low in protein and carbs and higher in healthy fats—the FMD is designed to suppress the insulin and Insulin-like Growth Factor 1 (IGF-1) pathways, which are associated with aging.

Potential Benefits of the 7-Day FMD

Numerous studies, many involving the commercially available ProLon FMD, have highlighted a range of potential health benefits from periodic FMD cycles. These benefits are often more pronounced in individuals with existing metabolic risk factors.

Potential benefits of the FMD include:

• Weight Loss and Fat Reduction: The calorie restriction and shift to ketosis promote fat burning, leading to reductions in overall body weight and fat, particularly visceral fat (belly fat).
• Improved Metabolic Markers: It can lead to improvements in metabolic health, including lower fasting glucose levels, enhanced insulin sensitivity, and reduced blood pressure.
• Cellular Rejuvenation: The activation of autophagy helps clear out damaged cells and promotes regeneration, supporting overall cellular health.
• Reduced Inflammation: FMD has been shown to reduce levels of inflammatory markers, such as C-reactive protein (CRP), which can benefit a variety of health conditions.
• Cardiovascular Health: By lowering blood pressure, cholesterol, and other risk factors, FMD cycles may contribute to better heart health.

A Sample 7-Day FMD Structure

For those creating their own FMD, the key is to follow the low-calorie, low-protein, and high-fat macronutrient ratios. The overall intake is typically around 1,100 calories on day one, followed by 700-800 calories on subsequent days. It is crucial to use a precise, medically approved plan or work with a healthcare provider, as homemade versions can be difficult to balance correctly.

General meal plan principles

• Day 1: Higher calorie allowance (e.g., 1,100 kcal) to initiate the fasting state.
• Days 2-7: Significantly reduced calorie intake (e.g., 700-800 kcal) to maintain the fasting state.

Recommended foods

• Healthy Fats: Olives, avocado, nuts (almonds, walnuts, macadamia nuts), and olive oil.
• Low-Carb Vegetables: Kale, spinach, broccoli, cauliflower, zucchini, and celery.
• Nutrient-Dense Liquids: Herbal teas, vegetable broth, and miso soup.
• Small amounts of plant-based protein: Lentils or chickpeas.
• Low-sugar fruits: Berries.

Foods to avoid

• Animal protein (meat, poultry, fish)
• Dairy products
• Refined sugars and processed foods
• High-glycemic carbs (white rice, pasta, bread)
• Alcohol

Comparison: 7-Day FMD vs. Water Fasting

Feature	7-Day Fasting Mimicking Diet (FMD)	Water Fasting (7+ days)
Food Intake	Specific, limited amount of food is allowed daily.	No food or calorie intake; only water.
Nutrient Intake	Provides essential vitamins, minerals, and healthy fats from plant-based sources.	No nutrients, increasing the risk of deficiencies.
Adherence & Hunger	Generally easier to adhere to due to some food intake; hunger is present but often less severe.	Can be very challenging due to complete food deprivation and intense hunger.
Safety & Side Effects	Clinical trials have shown it to be safe for healthy individuals under medical supervision; side effects are often mild.	Higher risk of severe side effects, electrolyte imbalance, and requires close medical supervision.
Efficacy	Studies suggest robust cellular regeneration and metabolic benefits.	Also promotes autophagy and metabolic changes, but can be more taxing on the body.

Who Should Avoid the 7-Day FMD?

While generally considered safe for healthy adults, the 7-day FMD is not suitable for everyone. It is crucial to consult a healthcare provider before beginning, especially if you fall into any of the following categories:

• Pregnant or Breastfeeding Individuals: The nutritional demands of pregnancy and lactation are significant, and calorie restriction is not recommended.
• Individuals with a History of Eating Disorders: The restrictive nature of the FMD could trigger or worsen unhealthy eating patterns.
• People with Specific Medical Conditions: This includes individuals with diabetes (especially those on insulin), kidney disease, heart disease, or those prone to malnutrition.
• Older Adults and Children: Fasting diets are generally not recommended for individuals under 18 or over 70 without explicit medical clearance.
• Those Undergoing Strenuous Activity: High-intensity exercise during the FMD is not advised due to reduced energy intake.

The Importance of Professional Medical Guidance

Due to the significant metabolic changes involved, approaching a 7-day fasting mimicking diet should be done with caution and professional oversight. Medical supervision can help ensure the diet is appropriate for your individual health status and can monitor for any potential adverse effects. A healthcare provider can also help you transition back to your regular eating habits safely after the diet to maximize its benefits and avoid weight regain. Some commercial kits, like ProLon, are backed by clinical research and offer pre-portioned meals, simplifying the process and ensuring nutritional targets are met. For those opting to create their own plan, the risk of miscalculating nutrients or calories is high, underscoring the need for expert guidance.

Conclusion

The 7 day fasting mimicking diet offers a promising method for inducing the cellular and metabolic benefits of fasting while consuming limited amounts of plant-based food. By promoting ketosis, autophagy, and a metabolic reset, it can contribute to weight loss, improved metabolic health, and cellular rejuvenation. However, its success and safety are highly dependent on strict adherence and proper medical guidance. For healthy individuals, it can be a powerful tool for wellness, but those with pre-existing conditions or certain life stages must seek professional advice to avoid risks. To explore the science behind FMD and its development, you can find authoritative information from the University of Southern California Longevity Institute.

Frequently Asked Questions

What is the calorie intake for a 7-day fasting mimicking diet?

Calorie intake typically varies throughout the cycle. Day one may be around 1,100 calories, while days two through five generally involve a reduction to 700-800 calories. The specific plan can vary, especially for a 7-day version.

Is a 7-day fasting mimicking diet better than water fasting?

For many, the FMD is a safer and more manageable alternative to water fasting. It provides essential nutrients from food, reduces the risk of nutrient deficiencies and electrolyte imbalances, and is often easier to adhere to than a total abstinence from food.

What foods can you eat during the FMD?

Allowed foods are primarily plant-based and include healthy fats like olives and nuts, low-carb vegetables such as kale and broccoli, and nutrient-dense liquids like vegetable broths and herbal teas.

What happens physiologically during a 7-day FMD?

During the FMD, your body depletes its glucose stores and switches to burning fat for energy (ketosis). This also activates autophagy, a cellular repair process, and lowers levels of IGF-1, a hormone associated with aging.

Are there side effects of the FMD?

Some common but mild side effects include fatigue, headaches, dizziness, and increased hunger, especially during the initial days. These effects typically subside as the body adapts to the low-calorie intake.

Who should avoid the 7-day FMD?

Individuals who are pregnant, breastfeeding, underweight, or have a history of eating disorders should avoid the FMD. People with conditions like diabetes, heart, or kidney disease should not attempt it without medical clearance.

How often should you do the FMD?

The FMD is not a long-term diet but a periodic one. Cycles are typically repeated every few weeks or months, depending on your health goals and a healthcare provider's recommendation.