ProLon FMD 5-Day Fast: How to Survive & Thrive with the Fasting Mimicking Diet

by Beth Graham
ProLon FMD 5-Day Fast: How to Survive & Thrive with the Fasting Mimicking Diet

If you’re staring at a bowl of soup, wishing it were an Italian sub, welcome to the ProLon experience. In this guide, I’ll share tips on how to survive the ProLon FMD 5-day fasting mimicking diet and why it’s worth it for your health journey. After completing the program twice, I’ve become a fan (and no, this isn’t a paid endorsement). I purchased the program because I was intrigued by the science behind it—how it promotes anti-aging, boosts cellular rejuvenation, and helps flush out old, damaged cells. Plus, I needed to shed a few menopause pounds and jumpstart a healthier lifestyle.

Let me walk you through what to expect from the ProLon FMD diet, how I survived both rounds, and how you can too!

My first ProLon experience compared to my second ProLon experience

ProLon 5-day fasting
  • Both times, ProLon Day 1 was pretty easy because I was so motivated. I was mildly hungry late in the day.
  • ProLon Day 2: The first time, day 2 was easy, just like day 1. I was still feeling motivated. This second time, I think I knew what to expect so my enthusiasm had waned, so day 2 was when my real hunger kicked in. I was even starting to give myself permission (or excuses) to have a regular dinner on ProLon Day 5 and break my fast (but I did not).  I also had a headache most of the day. 
  • ProLon Day 3: Most people say this is the hardest day. I’ll admit I was hangry (I mean, when am I not?), but my determination carried me through. I was feeling a bit more energy and creativity on Day 3 the second time around.
  • ProLon Day 4: The first time I did Prolon, this was the worst day for me. I was hungry and had no energy. I laid in bed watching food TV shows all day and longing for something decadent. I was pretty miserable. But the second time through, I had a markedly different experience. I woke up feeling very energized and felt great all.

What is the ProLon FMD Diet?

  • The ProLon FMD (Fasting Mimicking Diet) is a revolutionary nutrition program developed by Dr. Valter Longo at the University of Southern California. It’s designed to mimic the effects of fasting while allowing you to consume small amounts of food, supporting cellular renewal and metabolic health. By keeping your body in a fasting state while nourishing it with carefully measured nutrients, ProLon promotes autophagy (the body’s process of removing damaged cells) without the harshness of a complete water fast.

What to Expect from ProLon FMD 5-Day Fast: Day-by-Day Breakdown

Here’s a detailed look at what each day on ProLon is like, based on my personal experience.

  • ProLon Day 1: The Easiest Start
  • The first day is a breeze. You’re motivated, excited, and ready to see results. You’ll enjoy Prolon nut bars for breakfast and plant-based soups for lunch and dinner, along with tea, olives, and kale crackers. Everything is pre-packaged, making it easy to follow the plan without thinking about what to eat.
  • ProLon Day 2: Hunger Kicks In
  • Day 2 is when the real hunger sets in. The initial excitement starts to fade, and you’ll notice the calorie reduction. You might feel tired or get a headache, but don’t worry—this is your body adjusting to the fast. Stay hydrated, and keep reminding yourself why you started.
  • ProLon Day 3: The Hump Day
  • Most people report that Day 3 is the hardest. I’ll admit, I was hangry (hungry and angry). My advice: add extra water to your soups, take short walks to distract yourself, and keep busy. It’s important to push through this day because it’s when your body enters deeper into a fasting state and cellular rejuvenation begins.
  • ProLon Day 4: Gaining Momentum
  • By Day 4, things start to get easier. Your hunger stabilizes, and you may notice an increase in energy as your body adapts to the fast. I was surprised by how good I felt and even considered going to a yoga class—but it’s best to avoid intense physical activity during ProLon. Focus on light exercises, like walking.
  • ProLon Day 5: Reaching the Finish Line
  • Day 5 is all about victory! You’ve made it this far, and it’s easy to keep going knowing the end is near. By the end of the day, I felt accomplished and energized. Stick to the plan, and avoid the temptation to reward yourself with a big meal. Follow the program’s instructions for easing back into regular eating. throughout the day – I even considered going to a barre or yoga class but decided not to push it. I never felt any hunger and even got tied up and did not have “lunch” until 4pm.
  • ProLon Day 5: Victory! It was an easy day because I knew the end was near. What a sense of accomplishment! I will say I definitely felt that boost of energy that others reported the second time through. True confession: on my second fast, I almost caved on Day 5 and had a piece of bread with my dinner. I was pretty hungry. But I decided I’d rather get up early and have an “honest” real breakfast – I had worked too hard to cheat at this point.
  • ProLon Day 6: It’s important to ease back into eating as you break the fast. The program offers some guidance on what to eat, primarily soup and light veggies. I opted for avocado toast for breakfast, whole wheat pasta for lunch, and a small chicken breast with veggies for dinner.

ProLon FMD 5-Day Fast Benefits: Why You Should Try It

The benefits of ProLon go beyond weight loss. After completing my first round, I dropped 5 pounds, and in my second round, I lost another 3.6 pounds, keeping it off for months. But the benefits aren’t just about losing weight.

ProLon helps kickstart the body’s natural anti-aging processes. By mimicking fasting, the diet triggers autophagy, which helps your body clear out old, damaged cells and replace them with healthier ones. This process has been linked to improved metabolic health and longer lifespan.

Although weight loss is a common benefit, the real value of ProLon lies in the lasting health effects. Many participants report increased energy, better focus, and an improved relationship with food. After my second fast, I found myself eating less and making healthier food choices, which is a long-term benefit I didn’t expect.

How to Prepare for ProLon FMD 5-Day Fast

Before starting the ProLon diet, preparation is key to surviving the five days. Here are a few tips that helped me get through it.

First, plan your fast when you have no major social commitments—trust me, you don’t want to watch someone eat a cheeseburger while you sip soup! Mentally prepare for the hunger and fatigue you’ll feel on days 2 and 3. Remind yourself of the long-term benefits to stay motivated.

If you’re a mindless eater like me, ProLon will shine a light on this habit. Use the fast as an opportunity to break bad habits and focus on mindful eating. Eat your meals slowly, savoring each bite, and stay away from the kitchen to avoid unnecessary temptation.

Tips for Surviving the ProLon Fasting Mimicking Diet

Here are a few tips that helped me through both rounds of ProLon and kept me on track.

I added a little cayenne pepper, black pepper, and sometimes cumin to my soups to make them more enjoyable. Adding extra water to the soups also helps increase the volume and make you feel fuller. Drink plenty of water, and if you find plain water boring, try adding hibiscus tea or sparkling water to mix things up.

Although you shouldn’t do intense workouts, I found taking short walks helped me manage my energy levels. Don’t feel guilty about taking it easy—your body is working hard on a cellular level. Save the workouts for when you finish the fast.

You’ll inevitably feel hungry during ProLon, especially in the first few days. My advice? Eat slowly. Stretch out your meals by savoring each bite, and distract yourself by engaging in activities that keep you busy, like reading, writing, or going for a walk.

Frequently Asked Questions (FAQ)

How Often Should You Do the ProLon Diet?

The ProLon program recommends doing the fast once a month for three consecutive months to see the best results. However, individual results may vary, so consult with your healthcare provider for personalized guidance.

Can You Drink Coffee on ProLon?

While the program discourages caffeine, you’re allowed to have one cup of black coffee each morning to avoid caffeine withdrawal headaches. Try to stick to herbal teas if possible.

How Much Weight Can You Lose on ProLon?

On average, participants lose 5 to 8 pounds during a ProLon cycle. However, the real benefits are the improved metabolic health and anti-aging effects.

Is ProLon FMD 5-Day Fast Worth It?

I’ve now completed my third round of the ProLon FMD diet, and each time it gets easier. The health benefits—improved metabolism, weight loss, and anti-aging effects—make it worth the effort. If you’re considering trying the ProLon diet, just remember that it’s not about quick fixes. It’s about building healthier habits and rejuvenating your body from the inside out. Ready to give it a try? Share your ProLon experience in the comments below, or let me know if you have any questions!

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