Last week, I embarked on my first ever fast — both for personal reasons and to see firsthand how it could benefit many of my clients. But this wasn’t your typical starvation fast or juice fast that leaves you ravishingly hungry by day two. The fast I did was what’s called a fasting mimicking diet, which is a low-calorie, high nourishment fast where you are allowed to eat, but in very specific quantities.


I absolutely loved the 5-day fasting experience and have recommended this approach to many of my clients already, so I wanted to share all about what this kind of fasting is, the benefits, who it’s for, and my experience.


Watch my video below or read on to find out more.


What is a Fasting Mimicking Diet?

The fast I did was created by ProLon and born out of two decades of NIH/NIA-sponsored research at the Longevity Institute of the University of Southern California. (Note: This is not a paid or affiliate post, I purchased the kit on my own and am posting this out of my own interest).


The fasting mimicking diet is designed to provide the body with specific foods and ingredients that have been studied to actually reprogram the body into a regenerating and rejuvenating mode, which can improve healthy aging, reduce weight and abdominal fat, and even preserve lean body mass. Many foods we eat today actually promote aging as they put a stress on the body (hello, sugar, gluten, and food additives!) So the nutrients in this 5-day plant-based meal program are those that instead promote healthy aging and healthy metabolism levels to put the body in regeneration mode.


In clinical trials, they also found that it helped maintain healthy glucose levels, blood pressure, cholesterol, triglycerides, c-reactive protein, embryonic stem cells, and IGF-1. Woah!


A bit of a skeptic when it comes to lofty claims like that, I did a lot of research on their method and ingredients (more on that in a moment) and talked with several coaches and FDNs that had also gone through the 5-day fast to see if this was all it’s chalked up to be. My research came up overwhelmingly positive so I decided to give it a whirl.


How the Fast Works

ProLon made what could have been a daunting 5-day program easy and straightforward. Just 5 days of simple, delicious plant-based foods scientifically formulated to fuel the body while giving you all the benefits of a true fast and none of the adverse effects (aka feeling hangry!). Soups, bars, snacks, teas, drinks, and supplements are all included (oh, and did I mention they’re organic?!)


prolon fasting mimicking diet review         prolon fasting mimicking diet review


What ProLon does is it basically exploits the ability of the body during periods of low calorie intake to enter a protected mode so it can remove damaged cells and tissues and undergo self-repair. Several of their more recent studies have found that in a 5-day period, the immune system may be able to altogether regenerate itself. So not only does it have many potential weight loss and anti-aging benefits, it also can provide a big boost to the immune system. Having an autoimmune disease myself (ulcerative colitis), you can bet this was why I did it!


Starting on Day 1, you consume 1150 calories, and from days 2-5, you bump down to 800 calories. I really appreciate how they gradually introduce you to the fast in this way, as it allows the body to prepare, rather than being shocked into a fast. Each day’s meals are pre-portioned out and no two days are exactly alike, giving your tastebuds an adventure and keeping the program interesting.


Benefits of Fasting

I’ve become more and more an advocate of fasting of multiple varieties in the last year. Fasting gets a bad rep sometimes as we often think of it in terms of complete deprivation or fancy, expensive green juices. But what I like most about fasting from a physiological perspective is it gives the body a break from digestion to focus on repair and rejuvenation. Especially if you’re suffering from a digestive health condition, there is often damage in the GI tract that can only truly be tended to when there isn’t food running through it. If you’re prone to over-eating or snacking often, there is always going to be food in the system, leaving very little time for the body to clear things out and focus on cellular repair.


That’s why at the beginning of this year I started doing intermittent fasting 3-4 days out of the week. This meant for 12-18 hours a day I wasn’t eating anything but liquids like water or herbal tea. Typically I would stop eating (dinner) by 8pm and not eat again (breakfast) until about 11am the next morning. Intermittent fasting can be quite easy when you do it overnight and does take some training if you’re a breakfast person, but I eased into it within a week and have loved it ever since.


So, the 5-day fasting mimicking diet was another step in that progression for me, and can be for you, too. If intermittent fasting offers many benefits, you can guess how 10x’ing that time period with a 5-day fast can benefit the body.


Here are the benefits of ProLon specifically, as discovered in clinical studies:

  • Decreases body fat
  • Decreases body weight
  • Preserves lean body mass
  • 60% weight loss maintained for up to 3 months after resuming a normal diet
  • Maintains health levels of fasting blood glucose, c-reactive proteins, stem cells, and more
  • Improvement in energy levels
  • Healthier looking skin
  • Improved immune function


Especially interesting to me is they’re currently doing research on the benefits of ProLon for Crohn’s and ulcerative colitis. More on that as they release new information.


Just about anyone can benefit from a 5-day fasting mimicking diet, whether you’re looking to lose weight, maintain healthy blood pressure or cholesterol levels, or just want to maintain a healthy lifestyle and promote successful aging. Those with cancer or diabetes or other serious health conditions should, of course, contact their health provider prior to beginning any program like this as it may not be right for you.


If you would like to try ProLon, contact me here.


My Experience on ProLon’s 5-Day Fasting Mimicking Diet

I’ve gone through the fast and am already eager to try another one soon. So how did it go for me? Let me give you a quick breakdown:


Day 1. This felt like a pretty normal day as I was eating 3 meals plus two snacks and teas! At 1150 calories, it wasn’t depriving at all. I was most impressed at the taste and quality of the ingredients. No nasty, hidden ingredients (yes, I scoured the ingredient labels!) and each meal, whether it was the tomato soup or quinoa bowl or kale crackers, was so savory! I could get used to this.

prolon fasting mimicking diet review     

Day 2. Okay, this was my toughest day. Going from 1150 to 800 calories on a normal workday was difficult for me, but I heard that days 2 or 3 could be the toughest depending on how many calories you usually consume, so I went into the day with this mentality and pushed through. A few times stomach grumbles almost got the best of me, but I just drank more water and herbal tea (they give you a BUNCH of teas which I loved!) and that seemed to do the trick. I took it easy on this day and went to bed early to make it more tolerable and that helped a lot.


Day 3. I was over the hump and was feeling amazing on day 3! I hardly felt hungry for breakfast that morning, so I chose to slowly munch on my breakfast bar (which, by the way, I was obsessed with and can’t wait to make a version of at home soon!). I wasn’t hungry for lunch until about 2:30pm and had dinner around 8pm. Oh, and my energy was higher than it usually was on a normal day, and this was all without caffeine (you can have up to 1 cup of black coffee or black tea if needed, but I chose most days not to do this).


Day 4. Dare I say I felt even better on day 4! My hunger was even more subsided, so I chose to delay some of my meals until later than usual and chewed/sipped on them slowly.


Day 5. I was honestly sad to know this was the last full day of the fast. Energy was still up, sleep was great, stomach was feeling wonderful, and I almost forgot what cravings were like!


Day 6. This was a transition day. Although this day was not a part of the ProLon program itself, they recommend not going back to your normal eating right away but to take a day to ease into “real” food by drinking juices and smoothies and later transitioning to soft foods like gluten-free pasta or rice. I did just that and it helped a lot.


Day 7. This is the first real day back on “normal” food. I was a little apprehensive to eat as I wasn’t sure how I’d feel as I was feeling so great on the program. So I stuck to smaller portion sizes and ate slower, which helped. I will say the first truly solid food I had, I could actually feel it traveling down my digestive tract which was a strange feeling!


Since completing the fast, I’ve noticed far less hunger cravings, have been eating much smaller portion sizes, eat a lot slower, and am better able to appreciate the taste of my food. These were just a few of the many things I learned during the fast and am excited to incorporate those learnings into my daily life.


A Few Pro-Tips

One of the reasons I like to try new health advances like this are so I can talk from first-hand experience about them to my clients. Having gone through the ups and downs of the program, there were a few tips I learned along the way that, if you plan to do this fast, you should be mindful of as well:


    1. Eat slow. You are eating reduced calories, so rather than speed through meals only to feel hungry quicker, I recommend each time you take a bite, you put down the soup spoon or the bar or cracker to enjoy the taste and chew fully. This can extend the meal time by quite a lot, leaving you less hungry in between meals.
    2. Add more water to the soups. Each day you’ll have 1-2 soups as your meals: Tomato soup, minestrone soup, or vegetable soup. There is also a quinoa blend for a few of the meals. For each of these, you can add another cup or so of water to make the meal size larger and help to extend the amount you consume to keep you feeling fuller longer. ProLon is a step above a water fast, so the more water you have, the better!
    3. Drink lots of water and tea during the day. You’d be surprised how often our body mistakes hunger for dehydration. This program teaches you that water is your friend and can help sustain you in between meals. And I mentioned earlier, they provide you with many herbal teas: spearmint, spearmint and lemon, and hibiscus.
    4. Follow the program exactly. ProLon makes it easy to follow exactly what to do each day, so do just that. You should not eat any food outside of what’s in each box as it may take you out of fasting mode. Remember that researchers took two decades to discover the exact nutrients and quantities of food to have to sustain the body for these 5 days, so don’t mess with science!
    5. Do NOT exercise or over-exert yourself. Extreme calorie restriction means you need to reserve your energy for just the basics of your day. Don’t plan to go to your normal spin class or 5-mile run during these 5 days. You’ll likely lose some weight during the program as it is, while still maintaining lean muscle mass, so put exercise on hold and focus on self care this week by doing things like taking epsom salt baths, meditation, light yoga, reading a good book, or sleeping more.


If you would like to try ProLon, contact me here. I am a certified practitioner who can work with you to implement the program, and when you sign up through me as a client, you receive $40 off the full price of the program ($200 instead of $240).


Have you tried Prolon? I’d love to hear how your experience was in the comments below!

Health Benefits of a 5-Day Fasting Mimicking Diet and My Personal Experience






Kristin Thomas is a health coach and Functional Diagnostic Nutrition Practitioner specialized in helping women with hormone, digestion, and autoimmune health concerns. Having gone through these health challenges herself, she now helps clients find their own path to complete wellness through practical and natural diet and lifestyle changes.





Get a Copy of My Free

Gut Healing Recipe Guide

Do you worry that you're eating the wrong foods? While certain foods are fantastic for gut health, others can be extremely damaging. Do you know the difference? This FREE guide contains recipes loaded with gut-healing foods so that you'll know exactly what you can eat to feel your best.






Leave a Reply

Your email address will not be published.