My Anti-Aging ProLon Fast Mimicking Diet Review

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This post contains affiliate links, but the review is my own. I received the ProLon box for free, in exchange for my honest review.

The science behind the anti-aging benefits of fasting and calorie restriction is getting stronger. That’s why I was anxious to try the ProLon Fast Mimicking Diet. Here is my honest review!

During fasting, or calorie restriction, our bodies go through what is called autophagy. It’s a way we clean up and remove damaged intracellular components (worn out parts, proteins that don’t function right and such) to self-repair. Studies show, this rejuvenation can slow down the aging process, at least in mice (the jury is out on humans). This study found here provides a great explanation on how it works. (and more studies are linked here)

So, when I read Valter Longo and his studies into fasting and health, I was intrigued. In it, Dr. Longo talked about developing The ProLon Diet, which is a 5 day program that makes your body think it’s fasting, without going hungry. This way you are supposed to get many of the benefits of a fast, without the struggle of going hungry.

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What is the Prolon Diet?

The ProLon Fasting Mimicking Diet (FMD) is 5 days of pre-portioned and packaged foods, that provides just enough food in the right proportion of
micro and macronutrients for your body to think you are fasting, while providing you with the nourishment to support metabolism and energy.

The 5 day ProLon Diet isn’t cheap. It retails for $250, (update: November 2021 use Discount Code: prolon15 for $84 off!) even though there isn’t much food in the box! But, on the plus side, if you spend that kind of money on a program like this, you’ll probably be 100% compliant for the 5 days, just so you aren’t wasting your money! I definitely was compliant for the full 5 days!

What do you eat on the Prolon Diet?

The meals you get inside the Prolon Fast Mimicking Diet box are simple. They are low in protein and carbs, and moderately high in fat. The fat comes mostly from the crackers, nuts, and olives. The food in the Prolon Diet box includes teas, vitamins, soups, olives, bars, crackers, and a special formulated drink.

The box from Prolon fast mimicking diet (FMD)

It starts the first day with around 1100 calories, with the remaining days between 660-800 calories.

Each day there is some combination of:

  • The L-Bar. It’s a chewy nut bar that to me, tastes like a Larabar, which I already love!
  • Three soups, in different combinations on different days. Tomato, minestrone, vegetable and quinoa minestrone.
  • A few of the days had sesame kale crackers (that were SO GOOD)
  • Olives on a few of the days, with either garlic or sea salt flavoring.
  • And a choco crisp bar on a few of the days.
  • Herbal tea packets. Mint, mint and lemon, and hibiscus.
  • And then there were supplements like a drink, and some vitamins.
Prolon fast mimicking diet meals

My Review and Results of the Prolon Diet

I wasn’t following the Prolon Diet program to lose weight, but I did lose 5 lbs during the 5 days. 8 lbs if you count the three extra pounds I weighed the morning after Christmas! (see on the chart below. I weighed 113 at 5 am, but at 8am I was 110.8 lbs. LOL. I weighed again because I just got the box and I wanted a true pre-Prolon weight. (read my weight loss story here)

prolon weight loss scale chart

Here’s the scale. I should have taken a photo of the 110.8 lbs, but I wasn’t thinking it would be so different.

weight loss from prolon

While it’s impossible to know if I experienced any anti-aging benefits, I did feel great during the 5 days.

  • I had plenty of energy.
  • I was 100% more productive at work (probably because I wasn’t eating all day)
  • I slept well.
  • And I wasn’t bloated at all. (even though the manufacturer doesn’t claim this as an effect of ProLon. I tend to overeat on low calorie food because I like to feel full, but as a result, I always feel bloated! On this program, the food is minimal, so my stomach was flatter than it’s been in awhile.

Could I have achieved the same feeling by limiting my calories on my own? I think I could, although it would be harder. The reason following the program worked for me was because I was mentally committed to the full 5 days, and I didn’t have to think about or calculate my food intake. The more time I spend in the kitchen preparing food, the more I eat. But with the box of pre-made food, I spent almost zero time in the kitchen, eliminating most temptations.

What surprised me was how bored I was! I am shocked at how often I thought about going to get a snack, just to entertain myself! I hope moving forward, I can catch myself before I reach for food out of boredom.

One strategy I employed to get through the 5 days was to stay busy and intentionally distracted. If I spent time thinking about the fact that I was fasting, or that I could only eat the food that I got out of the box, I would just crave other, more entertaining food. But If I could watch a movie or get lost in my work, I was able to get through the day a lot easier. (This also was my strategy while I prepared for the NPC Bikini competition! Distracting myself from snacking all day was key!) (That story of my bikini transformation here!)

What did the 5 Days of Prolon look like?

Prolon Day 1: Easy day! I woke up and weighed 113 lbs. It was the day after Christmas though, and I REALLY over did it on Christmas with food. However, a few hours later I weighed in at 110, and this was more appropriate as my starting weight, because it’s close to the weight I’ve been maintaining for awhile.

This was the day with the most food, and I could tell. I felt great. This day had 1035 calories, 25 g protein, 101 g carbs, 32 g fiber, 66 g fat, 30 g sugar, and I’ve been there before. It didn’t feel like a fast. I had plenty of energy and I was motivated to see the full 5 days through. I delayed breakfast till about 10, which also made it easier.

Prolon Day 2: Sunday- 690 calories, 15 g protein, 85 g carbs, 20 g fiber 36 g fat, 28 g sugar. I tried to keep busy. In the morning I went to church. Later, I watched a movie, and I felt good. The soup and granola bar were delicious! It may be that I was hungry for food. Food ALWAYS tastes better when you are hungry! I never liked olives before, but this day, they tasted amazing!

Tried to stay distracted. Didn’t feel tired or hungry. I preferred cooking the soup on the stovetop because it resulted in much thicker, voluminous soup. I literally licked every last drop out of the bowl, because I didn’t want to lose or waste one single calorie!

Prolon Day 3: 882 calories, 37 g protein, 97 g carbs, 25 g fiber, 41 g fat. 35 g sugar. Longest day so far. Literally, this day couldn’t end fast enough. I got up very early, so it made the day extra long. All I had going for me was work, and I had the thought MANY times that I should eat something. But I didn’t give in. We have lots of Christmas food leftover that I REALLY wanted to eat, but I didn’t. I went to watch a movie at about 5:00 pm to stay distracted, and fell asleep by 8pm. I was so glad to go to bed.

Prolon Day 4: 680 calories, 15 g protein, 86 g carbs, 21 g fiber, 35 g fat. 29 g sugar. I was determined not to make the same mistake of being bored and wanting to eat, so I slept in. I think I slept for 10 hours! When I finally woke up, I went to yoga, did some volunteer work and then worked the rest of the day. I successfully stayed distracted and I did not feel hungry at all. Lots of energy.

Prolon Day 5: FINAL DAY! 660 calories, 17 g protein, 73 g carbs, 21 g fiber, 37 g fat, and 17 g sugar! I wasn’t hungry. I wasn’t tired day 4 or 5. In fact, I had plenty of energy, and I was ULTRA productive. Not going to lie though.. I’m so glad it’s over! I don’t think I want to eat one more bowl of soup!

What I liked about the Prolon Diet:

  • It reinforced to me that calories do count! Although I wasn’t trying to lose weight, and the protein was so low and the fat higher than I normally eat, I did lose weight! It’s good for me to see results like this, because I tend to believe high fat diets, or low protein diets aren’t helpful for weight loss, but this proved me wrong. Calories are everything. (See my 5 steps on getting started with calorie counting here.)
  • You really get to know your mental garbage around food. Faced with your own thoughts, boredom, and stress without being able to use food to cope is tough! Finding new ways to cope is so important. Journaling, walking, or listening to music really helped me!
  • Being hungry is USUALLY just a product of me being bored. Wow. I hope I never forget this!
  • I don’t need to overfeed- or stuff myself on low calorie, high volume foods. It leads to me craving more high-volume foods. My stomach is flatter, and I feel lighter when I don’t stuff myself. I want to keep this feeling. For example, I can have one protein or meal replacement bar, and not turn it into a meal.
  • Hard to say if the benefits are realized because of the food, or because of the calorie restriction. They say you can’t do this with food you can buy at the store, but I’d be surprised if there was anything special about the food in the box.

What I didn’t Like about the Prolon Diet:

  • Hands down, the price! It’s a lot of money for a little bit of food.
  • Excessive packaging. I already don’t have enough space in my recycle bin from Christmas, so this huge box is going to have to wait until next week to recycle.
  • The teas and L-drink. I don’t drink tea, and most flavored drinks remind me of a colonscopy prep!

Would I do it again?

They say for optimal health, you could do this 5 day ProLon Diet every three or four months. I probably will do it again. While I don’t believe in cleanses (our livers are pretty good at cleansing naturally, and I never want to take weird drinks to promote cleansing), I do believe the science behind calorie restriction for rejuvenating good cells!

I’d love to hear if you’ve tried it and what your experience is! Let me know in the comments!

If you want to give it a try, I’ve got an affiliate link here, and you can use this Prolon coupon codes for 15% off! The discount coupon code is HEALTHBEET

Download the free 7 Day Meal Plan here.

If you liked these Printable Portion Sizes Chart options, you might also like

Prolon fast mimicking diet review lost 5 lbs in 5 days


  1. I’m on Day 4 – as opposed to the constipation many have on Prolon, I had terrible “intestinal hurry” most of yesterday and was up all night with stomach issues. I have IBS and really should have looked at the ingredients more closely. Not sure I’m going to continue as I’ve also GAINED 2 pounds. Thinking Prolon isn’t a good fit for me.

  2. Done prolon lost 8 lb… gain back 3lb in a couple of weeks.
    A month after I am still 5lb less.
    I was surprised how easy it was a how energetic I felt, I could crack the numbers like never before and had a high concentration level at work ( had to go to sleep by 8:30- 9:00pm and worked out less though )
    Starting my second cycle; today is day 1.
    So far feel confident and have less stress of unknown. I am sure the second round will go much easier. Now I know how to prepare my soups and how to manage and stretch my snacks.
    I had to take ibuprofen 400mg every day with my tomato soup to avoid a headache and protonix- since I have a gastritis. Also sugar-free tums helped.

    1. Natalia!I want to do a second round too.  About the gastritis, I know this would be a problem for me if I do it again. I’ve had a lot of stomach pain when my stomach is empty lately!  But since I’m rarely hungry (I eat a lot of food. haha),  it hasn’t been too much of a problem.
      Let me know how it goes on your last day!

  3. Amy, what about the impact on women’s hormones of Prolon. The hormones regulating key functions like ovulation are incredibly sensitive to energy intake so I’m curious of Prolon/USC conducted any studies on this diet (or other calorie fasting diets) on hormone levels.

    1. Hi Sarah!
      That would definitely be a question for Prolon, as I’m not an expert in the diet itself.
      However, I would think that 5 days isn’t really long enough to have a lasting impact on hormones. Our bodies are much more resilient to “feast or famine” than 5 days.

  4. I’m on the morning of day 4 and have only lost <2 pounds, which is crazy to me. I question whether it’s the high carb content of Prolon compared to the low carb vegan diet I normally consume. Any thoughts? Considering cutting out the bar to limit the carbs for the last two days. It’s just not worth it if I only lose 3 or 4 pounds total. And I do work out with cardio and resistance training but am taking it easy while on Prolon. I’m 56, so the weight does not like to budge. I’m 5’10”, 153.8 pounds on day 4 a.m. At this point I regret having ordered a second box. I get more anti-inflammation benefits from a 2-3 day water fast.

    1. Hi Julia,
      I’m so sorry, I am just getting to your comment.

      How did it go? I was going to say, even if the carbs are higher, the overall calories are so low, I would not cut carbs even more..

  5. I’m on day 4 and have a constant headache and feeling quite irritable. I’ve been drinking the teas and plenty of water but the headache won’t go away. Also have brain fog! Already down 5 lbs but not sire going through this misery is worth it! This is very tough..not sure how you have “lots of energy!” I’ve never heard anyone say that with prolon!

  6. Interesting article. I wanted to try it but I *detest* chocolate. I guess those of us that despise the taste of chocolate are out of luck with Prolon. 🙁

  7. Enjoyed your post regarding Prolon ! I am contemplating a purchase and wanted to see if you were able to work out during the 5 days. I work out 5-6 days a week and it will be hard to take a week off – can you do lighter weights and low impact workouts?
    Thanks so much!

  8. Thanks for the review, read it while on prolon and wondering if the brain fog is normal. I’m on day 2 and have serious brain fog, not much energy. I’m not hungry, probably because I’m used to fasting. Thanks again!

    1. Hang in there!! Everyone is different, and it didn’t happen to me. But I wouldn’t be surprised if this was normal! I think by tomorrow it should go away for you! Let me know.

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