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Results of My 5-Day Fasting Mimicking Diet

by Quantify Fitness | Last Updated:  January 26, 2019

What is the Fasting Mimicking Diet?


prolon fasting mimicking diet


Getting the Benefits of Fasting While Being Able to Eat

In the past, I've experimented with intermittent fasting and extended water fasting, so I was intrigued when I heard Dr. Valter Longo, author of The Longevity Diet, on multiple podcasts discussing the research behind his Fasting Mimicking Diet.

the longevity diet

After a couple clients mentioned trying it, and then hearing Dr. Rhonda Patrick on her podcast calling Valter Longo her go-to resource on longevity, I knew I had to at least give it a try; especially given I turned 40 last year and healthspan (not lifespan) has become a big focus of mine.

After $36 million dollars and decades of research with over 28 articles published, the claim is that this Fasting Mimicking Diet will give you the benefits of a 5-day fast while still being able to eat certain foods. The benefits listed on the website include:

No other meal or fasting program has been clinically tested for results or patented for anti-aging like the ProLon Fasting Mimicking Diet.

Because I'm such a health and data nerd, I was anxious to give this a try and compare it to previous fasts I've done.

My 5-Day Experience

Day 0:

The box that arrives contains everything you need. Inside is a bottle for the included energy drink, a meal reference card, and five smaller cartons labeled Day 1-5, each one providing the food you eat each day.

prolon fasting kit

Scientifically developed and clinically tested at the University of Southern California Longevity Institute and School of Medicine, one of the leading centers for research on aging and longevity, the diet is a plant-based program providing 1150 calories on day 1 and approximately 800 on days 2-5.

The program exploits the ability of the body during periods of low-calorie intake to enter a protected mode, remove damaged cells and tissues, and undergo self-repair. Evidence suggests that this process may result in increased longevity and improved health and wellness.

All of the provided foods and drinks are designed to maximize the protective effects related to fasting while providing micronutrient nourishment (vitamins, minerals, and essential dietary components), and minimizing hunger and the common burdens of fasting.

prolon meal card

Day 1: Fasting state. Priming your body to transition into a fasting state so it can begin cellular recycling

Even though I've followed a low-carb/keto lifestyle for the last few years this was the hardest day, primarily because I had to cut out coffee!

No other food or drinks are supposed to be consumed during the 5 days except water and herbal teas. They do allow 1 cup of caffeinated beverage per day, as long as there's no sweeteners or additives, but I really wanted to follow the program exactly as designed so I cut out all caffeine for the week.

By about 4 o'clock that afternoon I had a splitting headache. Wanting to avoid pain-killers, the best remedy I found was rubbing some peppermint oil on my temples, which actually did provide some relief – just don't get it too close to your eyes…I learned that the hard way!

The food tasted better than I expected and I even ended up ordering some extra boxes of their fast bars. Those bars tasted too good to be true for a program like this.

I also wanted to track my blood sugar and ketones using the Keto-Mojo to see how they would compare to previous fasts I've done. Anything over 0.5 mmol means you're in ketosis.

prolon day 1

Day 2: Fat burning. Your body is switching to fat burning. Cellular clean-up (autophagy) begins.

The second day wasn't too bad, and the headache from my caffeine withdrawal had subsided, but I did notice that I was pretty sluggish after lunch and dinner, probably still related to the lack of caffeine.

By Tuesday my ketones were above 1.0 mmol throughout the day and up to 1.8 mmol by the evening, right around the Optimal Ketone Zone as referenced by Dr. Jeff Volek and Dr. Stephen Phinney in their book, The Art and Science of Low Carbohydrate Performance.

optimal ketone levels

prolon day 2

Day 3: Cellular recycling

By Wednesday my energy levels were back to normal and it was smooth sailing.

I found it interesting that my morning blood sugar was over 100 at the same time my ketones were at 1.3 mmol. Typically there is more of an inverse relationship, where blood sugar is down when ketones are up. I wrote this anomaly up to the dawn phenomenon, a surge of hormones that the body produces daily in the early morning hours before waking up.

prolon day 3

Day 4: Cell regeneration. Autophagy continues and stem cell-based regeneration is ramping up.

Thursday was another easy day of following the program, but it was the first day I really started to desire other foods.

prolon day 4

Day 5: Regeneration continues to enhance cellular renewal and the body.

The final day was similar to day 4, but my energy was really starting to climb. Unfortunately, I forgot my Keto-Mojo at the office so I couldn't do my evening reading.

prolon day 5


When I woke up on Saturday morning, my energy levels were through the roof and I felt better than I have in a long time, which is crazy because I already have pretty high energy levels after cleaning up my diet and starting to exercise smarter a few years ago.

Overall I lost about 7 pounds; 3 pounds of water and 4 pounds of fat. Once I started eating again the water weight came back and the fat stayed down 3 pounds.

In the end my body fat percentage fell from 14.5%, where it had been relatively consistent for months, down to 13.0%.

prolon fast weightloss

The other piece of information I was tracking throughout the process was the data on my Oura ring, arguably the best fitness tracker on the market. The data from that was amazing!

prolon heart-rate and hrv

At the end of the fast, I had recorded my lowest ever average resting heart rate and my highest average heart rate variability (HRV). You're likely familiar with resting heart rate in that it's a good measure of cardiorespiratory fitness.

Before the fast, I was hovering around the good range for my age (40-years old), but the fast dropped me down to 62 beats-per-minute and into the excellent category (my lowest average resting heart rate fell to 56)! What makes that even more amazing is that, just like most of our Quantify Fitness clients, I exercise for less than 1-hour per week – about 45-minutes a week to be exact (one Big 5 workout on ARX, one Vasper workout, and one CAR.O.L ride).

target resting heart-rate

If you're not familiar with heart rate variability, also know as HRV, it's a measure of the time variation between heartbeats. If your heart beats 60 times per second, the beats are not exactly one second apart, but more like 0.8 seconds, 1.1 seconds, 0.9 seconds, etc.. That information gives some insight into the autonomic nervous system and what it is doing – sympathetic (fight or flight) versus parasympathetic (rest, digest, and relax).

A higher HRV is linked to parasympathetic activity, the higher it is (more variation between beats) the more recovered we are. A low HRV is linked to stress and sympathetic activity, the lower it is (less variation between beats) the more run-down, depleted, and drained we are.

HRV analyzes how your body is distributing energy to stress and immediate demands, like recovery and adaptation. Our bodies have a finite amount of energy to:

  1. Stay alive – basic cell functions
  2. Deal with stress, including exercise
  3. Dedicate to growth, repair, and your immune system

Besides knowing the massive spike in my HRV shows my body was in ultimate recovery mode, it is also a good sign I could be getting a boost in stem cells, something that was shown to occur in the clinical trial done by Dr. Valter Longo when testing the Fasting Mimicking Diet.

Unrelated to Dr. Longo's research, research done at The University of Illinois showed stem cell proliferation is controlled directly by the nervous system. The body may avoid putting energy into making new cells when the fight or flight system is active or when food is coming in. So by utilizing a fasting protocol like The Fasting Mimicking Diet, the body may be able to elevate stem cell production, inducing immune system regeneration and shifting stem cells from a dormant state to a state of self-renewal.

According to ProLon, the stem cell-based rejuvenation continues for up to 5 days after you complete the program and return to your regular healthy meal plan.

Finally, I've already shared some of my previous health progress results here, specifically telomere age, where my cellular age improved by about 10 years, as well as my triglyceride to HDL ratio, one of the most predictive markers of cardiovascular risk – at or below 1.0 is optimal. I plan to update all my lab work in the next couple weeks to see if there are any more noticeable changes and I'll update this post if there are.

teloyears telomeres

hdl triglyceride ratio

Ready to Try It?

If you already come to Quantify Fitness you know we only promote products and services that we use personally and believe in strongly, and after going through this over the last week and seeing the positive results mentioned above: blood sugar, ketones, resting heart rate, HRV, and hopefully further improvements in the rest of my lab work, this is something we're adding to the list of recommendations.


5-day reset diet

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