The Fasting-Mimicking Diet (FMD) has garnered significant attention for its potential to promote cellular rejuvenation, weight management, and improved metabolic health. This article delves into the specifics of the FMD, offering a complete guide to understanding, implementing, and customizing this innovative dietary approach.
What is the Fasting-Mimicking Diet (FMD)?
The Fasting-Mimicking Diet (FMD) is a 5-day eating plan designed to trick your body into a fasting state while still providing essential nutrients. Developed by researchers at the University of Southern California, led by Dr. Valter Longo, the FMD is structured to restrict calories, control macronutrient ratios, promote cellular autophagy, and enhance metabolic flexibility.
Unlike water fasting, the FMD allows small, nutrient-dense meals, making it more sustainable while still triggering fasting-like benefits. This approach triggers cellular repair mechanisms similar to those activated during prolonged fasting, without the extreme deprivation.
How Does the FMD Work?
When you fast or drastically reduce calories, your body undergoes several metabolic shifts:
- Glycogen Depletion: After 12-24 hours, stored glucose runs out, forcing the body to burn fat.
- Ketone Production: Fat breakdown releases ketones, an alternative energy source linked to improved brain function and fat loss.
- Autophagy Activation: A cellular "recycling" process that removes damaged cells, potentially slowing aging.
- Reduced Inflammation: Fasting lowers inflammatory markers, benefiting long-term health.
The FMD mimics these effects without requiring a full fast, making it more accessible for beginners.
Read also: The Hoxsey Diet
FMD vs. Other Popular Diets
FMD vs. Intermittent Fasting (IF)
Intermittent fasting (IF) involves cycling between periods of eating and fasting. While both promote metabolic flexibility, key differences include:
- FMD: Deep cellular detox, anti-aging, metabolic reset.
- IF: Sustainable fat loss, blood sugar control.
FMD vs. Ketogenic Diet
The ketogenic diet is a high-fat, low-carbohydrate approach that aims to induce a state of ketosis for weight loss and improved metabolic function. While both the FMD and ketogenic diet promote ketosis, they differ in key aspects:
- FMD: A periodic metabolic "reset."
- Keto: Ongoing weight loss & neurological benefits.
ProLon Diet: The Commercial FMD Option
The ProLon diet is a commercially available fasting-mimicking diet (FMD) program. It offers a pre-packaged meal plan designed to mimic the metabolic effects of fasting while still providing essential nutrients, but they can be expensive. A DIY FMD is more affordable and customizable.
Similarities between ProLon and General FMD:
- Goal: Both the ProLon diet plan and the general FMD aim to mimic the metabolic effects of fasting, potentially promoting cellular rejuvenation, weight loss, and improved health markers.
- Calorie Intake: Both approaches restrict calorie intake to around 500-600 calories per day.
- Macronutrient Ratio: Both emphasize a specific ratio of carbohydrates, proteins, and fats, typically around 10% carbs, 15% protein, and 75% fat.
- Duration: Both the ProLon diet and the general FMD last for five days.
Differences between ProLon and General FMD:
- Convenience: The ProLon diet offers pre-packaged meals, eliminating the need for planning and preparing your own version of FMD meals.
- Cost: The ProLon diet can be significantly more expensive compared to a DIY FMD approach.
- Variety: The ProLon diet provides a set menu, whereas a DIY FMD allows for more flexibility in meal choices within the FMD guidelines.
- Availability of Scientific Research: While research is ongoing for the FMD in general, the specific benefits of the ProLon diet may not be as extensively studied.
Who Should Try the FMD? (And Who Should Avoid It)
Ideal Candidates for the FMD
- Those seeking cellular rejuvenation (anti-aging benefits)
- People with metabolic concerns (prediabetes, insulin resistance)
- Individuals looking for a short-term weight loss jumpstart
- Biohackers interested in autophagy & longevity
Who Should Avoid the FMD?
- Pregnant or breastfeeding women
- People with eating disorders or a history of extreme dieting
- Those with advanced diabetes (unless supervised by a doctor)
- Underweight individuals or those with nutrient deficiencies
Important Considerations Before Starting the FMD
- Consult your doctor: It's crucial to discuss the FMD with your doctor before embarking on this program, especially if you have any pre-existing health conditions, are pregnant, or breastfeeding.
- Not a cure-all: The FMD is a dietary intervention, not a magic bullet for health. It should be combined with a healthy lifestyle for optimal results.
- Potential side effects: The FMD may cause mild side effects like fatigue, headaches, and nausea during the first few days. These typically subside as your body adjusts.
DIY Fasting Mimicking Diet: A Complete 5-Day Meal Plan
For a more budget-friendly option, you can create your own FMD meal plan. Here's what you need to know:
Macronutrient Breakdown (Per Day)
The FMD targets a specific ratio of macronutrients:
Read also: The ultimate guide to keto stews
- Carbs: 50-60g (leafy greens, cruciferous veggies, berries)
- Protein: ~20g (nuts, seeds, tofu, small fish portions)
- Fats: 120-130g (avocado, olive oil, coconut, nuts)
Foods to Eat
- Vegetables: Spinach, kale, broccoli, cauliflower, zucchini
- Healthy Fats: Avocado, olive oil, nuts, seeds
- Proteins: Tofu, tempeh, small portions of fish/chicken
- Beverages: Water, herbal tea, black coffee (no sugar)
Foods to Avoid
- Grains (even whole grains)
- Starchy veggies (potatoes, corn, peas)
- Sugary foods & processed snacks
- High-fat meats (bacon, sausage)
5-Day FMD Meal Plan (500-600 kcal/day)
Here is a sample 5-day meal plan you can follow:
- Day 1:
- Breakfast: Green smoothie (spinach, almond milk, chia seeds, ½ cup berries) - 150 kcal
- Lunch: Creamy cauliflower soup - 200 kcal
- Dinner: Stir-fried tofu with sesame oil & veggies - 200 kcal
- Day 2:
- Breakfast: Chia pudding (almond milk, chia seeds, walnuts) - 180 kcal
- Lunch: Grilled chicken salad (mixed greens, olive oil dressing) - 220 kcal
- Dinner: Roasted Brussels sprouts with garlic & lemon - 150 kcal
- Day 3:
- Breakfast: Scrambled Eggs with Mushrooms & Spinach (200 kcal)
- Ingredients: 2 eggs (or ½ cup tofu scramble for vegan option), ½ cup mushrooms, sliced, 1 cup spinach, 1 tsp olive oil, Pinch of turmeric & black pepper
- Instructions: Heat olive oil in a pan. Sauté mushrooms until soft, then add spinach. Scramble eggs (or tofu) with turmeric and pepper.
- Lunch: Lentil Soup with Steamed Broccoli (250 kcal)
- Ingredients: ½ cup cooked lentils, 1 cup vegetable broth, ½ cup broccoli florets, 1 tbsp olive oil, Garlic, cumin, salt to taste
- Instructions: Simmer lentils in broth with spices for 15 mins. Steam broccoli separately. Drizzle with olive oil before serving.
- Dinner: Baked Salmon with Roasted Asparagus (200 kcal)
- Ingredients: 3 oz salmon fillet, ½ cup asparagus, 1 tsp olive oil, Lemon wedge, salt, and pepper
- Instructions: Toss asparagus in olive oil, roast at 400°F for 12 mins. Bake salmon for 10-12 mins with lemon and seasoning.
- Breakfast: Scrambled Eggs with Mushrooms & Spinach (200 kcal)
- Day 4:
- Breakfast: Greek Yogurt with Berries & Chia Seeds (180 kcal)
- Ingredients: ½ cup plain Greek yogurt (2% fat), ¼ cup mixed berries, 1 tsp chia seeds, 1 tsp almond butter (optional)
- Instructions: Mix yogurt with berries and chia seeds. Drizzle with almond butter if desired.
- Lunch: Tofu & Veggie Stir-Fry with Almond Oil (200 kcal)
- Ingredients: ½ block firm tofu, cubed, 1 cup mixed veggies (bell peppers, zucchini, bok choy), 1 tbsp almond oil, 1 tsp tamari (low-sodium soy sauce)
- Instructions: Sauté tofu in almond oil until golden. Add veggies and tamari, stir-fry for 5 mins.
- Dinner: Cauliflower Rice with Chicken & Herbs (200 kcal)
- Ingredients: 1 cup riced cauliflower, 2 oz grilled chicken breast (or tempeh for vegan), 1 tsp olive oil, Fresh parsley, lemon juice
- Instructions: Sauté cauliflower rice in olive oil for 5 mins. Top with chicken and herbs.
- Breakfast: Greek Yogurt with Berries & Chia Seeds (180 kcal)
- Day 5:
- Breakfast: Green Smoothie (180 kcal)
- Ingredients: 1 cup spinach, ½ avocado, ½ green apple, ½ cup almond milk
- Instructions: Blend all ingredients until smooth.
- Lunch: White Bean & Kale Soup (200 kcal)
- Ingredients: ½ cup white beans, 1 cup kale, chopped, 1 clove garlic, 1 tbsp olive oil, Vegetable broth
- Instructions: Simmer beans, kale, and garlic in broth. Drizzle with olive oil before serving.
- Dinner: Baked Cod with Lemon & Roasted Brussels Sprouts (220 kcal)
- Ingredients: 4 oz cod fillet, ½ cup Brussels sprouts, 1 tsp olive oil, Lemon zest, salt, pepper
- Instructions: Roast Brussels sprouts at 400°F for 15 mins. Bake cod with lemon zest for 10-12 mins.
- Breakfast: Green Smoothie (180 kcal)
Key Notes for Success
- Stay hydrated (herbal tea, water, electrolytes).
- Avoid snacking-stick to the 3 meals/day structure.
- Monitor portions (use a food scale if needed).
- Listen to your body-adjust if feeling overly fatigued.
Other Delicious & Easy FMD Recipes
- Creamy Cauliflower Soup:
- Ingredients: 1 head cauliflower, chopped, 2 tbsp olive oil, 1 onion, diced, 3 cups vegetable broth, ¼ cup almond milk, Salt, pepper, turmeric
- Instructions: Sauté onion in olive oil until soft. Add cauliflower & broth; simmer 20 mins. Blend until smooth, then stir in almond milk & spices.
- Tofu Scramble with Spinach:
- Ingredients: ½ block firm tofu, crumbled, 1 tbsp olive oil, 1 cup spinach, ¼ tsp turmeric (for color & anti-inflammatory benefits)
- Instructions: Heat oil in a pan, add tofu, and cook until slightly browned. Stir in spinach until wilted. Season with turmeric, salt, and pepper.
- Spinach and feta omelet: Crack two eggs into a bowl and whisk them together with a handful of spinach and crumbled feta cheese. Then put some olive oil into a nonstick pan and pour the mixture into that.
- Smoothie: Take One Cup of any type of frozen berries that you like and mix that in with half a banana, half a cup of almond milk, and a handful of spinach.
- Turkey lettuce wraps: Take lettuce leaves and play sliced Turkey, cucumber, and tomato inside.
- Greek salad: Toss together whatever mixed greens you like, cucumber, tomato, feta cheese, and olives.
- Grilled chicken with zucchini noodles: Take a chicken breast and marinate it in olive oil, lemon juice, and herbs of your choice.
Maximizing Your FMD Results: Best Practices
Before Starting
- Consult a healthcare provider (especially if on medication).
- Prep meals in advance to avoid temptation.
- Hydrate well (herbal teas, electrolytes).
During the FMD
- Stick to the plan-no cheat snacks!
- Manage hunger with herbal tea or broth.
- Rest & recover-avoid intense workouts.
After the FMD
- Gradually reintroduce foods (start with soups & steamed veggies).
- Track how you feel-note energy, digestion, and mental clarity.
Additional Tips:
- Incorporate Flavor: Use herbs, spices, and low-sugar condiments to add flavor to your FMD meals without exceeding your calorie or carbohydrate limits. This can make the experience more enjoyable.
- Support System: Having a supportive network of family or friends can be helpful during the FMD. Let them know about your plans and seek their encouragement to stay on track.
- Explore FMD Resources: Several online resources and cookbooks offer FMD-friendly recipes and information. Utilize these resources to create a delicious and varied meal plan for your FMD cycle.
Potential Benefits & Risks of the FMD
Science-Backed Benefits
- Boosts autophagy (cellular cleanup)
- Improves insulin sensitivity
- Supports weight loss (short-term)
- Reduces inflammation
Possible Side Effects
- Fatigue or headaches (usually temporary)
- Digestive changes (due to low fiber)
- Nutrient gaps (supplement if needed)
Real Food FMD Meal Plan
Day 1 (1100 Calories)
- Breakfast smoothie: 100 g avocado, 1 c spinach, 1 med banana, 1 c unsweetened almond milk. Add to blender with a little ice and blend.
- Mid-morning: 1 Quart of half green tea/half water with half a packet of LMNT electrolytes and 1tsp inulin.
- Salad for Lunch: 2 cups mixed greens, 150 g of tomato, 85 g of carrots, 100 g of cucumber, 40 g of avocado, 1/4c cooked brown rice, 5 olives, 1 tsp olive oil, Squeeze of lemon with salt, pepper, and a sprinkle of herbs, 5 Simple Mills almond crackers (Enjoy these! Or you can swap them for some almond milk in your coffee.)
- Snack: 10 olives, 200 g cantaloupe, 1 Quart of half green tea/half water with half a packet of LMNT electrolytes and 1tsp inulin.
- Dinner: Note: vegetables here are measured raw, then “sautéed” in a little water or just steam them to taste then sprinkle with salt, pepper, and a sprinkle of dried or fresh herbs. 170 g broccoli, 14 g sun-dried tomatoes, 30 g sliced baby Bella mushrooms, 1/2 c brown rice, 2 tsp olive oil (drizzled over cooked veggies), 8 olives, 4 oz kombucha (I put a splash into some seltzer with a wedge of lime), 1 square of 90% dark chocolate
Days 2-5 (800 Calories)
- Black coffee in the morning
- 1 Quart of half green tea/half water with half a packet of LMNT electrolytes and 1tsp inulin*
- Salad for Lunch: 2 cups mixed greens, 150 g of tomato, 85 g of carrots, 100 g of cucumber, 40 g of avocado, 1/4c cooked brown rice, 5 olives, 1 tsp olive oil, Squeeze of lemon with salt, pepper, and a sprinkle of herbs, 5 Simple Mills almond crackers (Enjoy these! Or you can swap them for some almond milk in your coffee.)
- Snack: 10 olives, 200 g cantaloupe, 1 Quart of half green tea/half water with half a packet of LMNT electrolytes and 1tsp inulin*
- Dinner: Note: vegetables here are measured raw, then “sautéed” in a little water or just steam them to taste then sprinkle with salt, pepper, and a sprinkle of dried or fresh herbs. 170 g broccoli, 14 g sun-dried tomatoes, 30 g sliced baby Bella mushrooms, 1/2 c brown rice, 2 tsp olive oil (drizzled over cooked veggies), 8 olives, 4 oz (1/2 c) kombucha (I put a splash into some seltzer with a wedge of lime), 1 square 90% dark chocolate
* Inulin is a fiber supplement powder that the Prolon product uses in beverages to help with fullness.
**I also took an omega-3 fish oil supplement daily, as this was included in the studies (and Prolon) as well.
Read also: Recipes for Gestational Diabetes
Design Your Own FMD Meals!
The FMD is a plant-based diet (no animal products) designed to attain fasting-like effects on the serum levels of IGF-1, IGFBP-1, glucose, and ketone bodies while providing both macro- and micronutrients to minimize the side-effects of fasting.
- Day 1 of the FMD includes ~1100 calories (11% protein, 46% fat, and 43% carbohydrate)
- Day 2 of the FMD includes ~800 calories (9% protein, 44% fat, and 47% carbohydrate) per day.
- From the Longevity Diet book, Longo suggests that a DIY version (for days 2-5) should include 400 calories from vegetables and 400 calories from fats such as olives, avocados, and nuts.
Here is a simple no-cook FMD meal idea with balanced macros that I have used before:
Avocado Toast: 1 slice Dave’s Killer Bread (110 calories) 50 g avocado
Salad: 2 c mixed greens 80 g carrots 80 g tomatoes 1 t olive oil squeeze of lemon or splash of vinegar, salt, pepper & a sprinkle of herbs if you like
This meal has a total of 324 calories, 9% protein, 47% fat, and 44% carbohydrates.
Additional FMD Meal Ideas
- Buy the Prolon bars or make your own. There are copycat recipes online. Just make sure to stick with the guidelines above.
- Use Amy’s organic soups for some or all meals, adding fats or carbs to meet the macro requirements.
- Use smoothies for meals, based on the recipe above or make up your own!
- Make a big batch of your own soup ahead of time. I made a vegan cauliflower soup during one of my FMD cycles and used that for several meals. This is a comforting and filling option especially during the colder months!
A Personal Experience with DIY FMD
I first discovered the Fasting Mimicking Diet while looking for a way to reduce my cholesterol. I’d read Dr. Longo’s book, the Longevity Diet, and was convinced that it really could make a difference in my cholesterol numbers. But I wasn’t crazy about the processed food option or its cost. I did some research and came up with my own plan based on what I’d found. Using MyFitnessPal to plan my food for the 5 days, I worked out the macronutrient ratios from Dr. Longo’s studies.
Like Dr. Longo’s studies, I did 5 days of the diet 3 times over several months. To measure whether this effort was truly helpful in my goal of lowering my cholesterol, I had bloodwork done before and after the experiment.
The results:
- Total Cholesterol Reduction of 13% into normal range
- LDL Reduction of 22% into almost normal range
- Triglyceride Reduction of 33% (this was in “normal” range before)
- HDL (“good” cholesterol) Increase of 8%
As a bonus, my fasting glucose came down 16 mg and I lost a few pounds. I was thrilled with the results, although my LDL was still not quite in the normal range of <100 mg. However, 6 months later it was exactly 100 and a year later it was 86.