ProLon Reviews - Does This Fast Mimicking Diet Work?

By Anthony Dugarte, M.D., C.S.C.S
Updated on: Apr 7, 2020

What is ProLon?

Prolon claims that their plant-based, prepackaged meal program will nourish your body, promote rejuvenation, support metabolic balance, and offer weight-loss benefits.

ProLon states that through a fasting-mimicking diet (FMD), the described goals may be accomplished.

They claim that these benefits are possible by consuming the ProLon meal plan for 5 consecutive days and avoiding liquids other than water or herbal, and caffeine-free teas during this timespan. After completing the cycle, simply resume your normal diet.

According to their website, your 5-day supply of meals will allow you to avoid the pitfalls of fasting while still reaping all of the benefits. ProLon claims that their methods were put to the test in a clinical study.

In this article, we’ll review the results of this study to help you determine if ProLon is a safe and effective means of losing weight and supporting overall health.

How Does ProLon Work?

ProLon’s meals come in five boxes (one for each day) that consist of a variety of plant-based foods like energy bars, soups, snacks, drinks, and dietary supplements that are low in carbohydrates and proteins while containing good fatty acids.

Their foods are free of additives, preservatives, or chemicals, and provide between 770 and 1,100 daily. Per the FMD guidelines, each meal is plant-based, low protein, and low carb, with an emphasis on healthy fats.

The company tells us that your body won’t recognize these calories as food, thereby helping you to maintain a fasting mode, without actually fasting. By avoiding being in a “fed state,” ProLon is alleged to reduce growth factors, glucose, inflammation, and signs of aging.

ProLon recommends following the FMD once per month, for 3 consecutive months. Once you finish 3 cycles, you can use the FMP as needed when you are interested in rejuvenation.

But can these methods really offer lasting weight loss? More on this in the next section.

Is There Any Science Backing ProLon’s Claims?

Fasting mimicking dieting was the brainchild of Valter Longo, who developed the program at the University of Southern California.

Though these methods are patented, the FDA did not evaluate them.

Fortunately, we do have some published results from a trial that specifically tested ProLon that may help shed some light on this topic.

The findings of this 2015 study were published in Cell Metabolism. Researches examined the effects of the FMD on yeasts, mice, and human subjects.

Testing on yeasts differed when compared to mice and humans in that the yeasts rotated between diets consisting of nutrient-rich foods or water only every 48-hours. This method of periodic starvation increased the lifespan of the yeasts, as well as their survival when exposed to hydrogen peroxide.

The method of fasting applied to mice in this study was comparable to the FMD offered by ProLon.

Mice were fed a low calorie, low protein, and low carb diet for 4 consecutive days twice a month. Mice on the FMD diet improved metabolism, cognitive function, and life expectancy. They also lost more weight, had a higher bone density, and less cancer when compared to placebo.

Humans tested in the study similarly received a low calorie, low carb, and low protein diet, though they followed this meal plan for 5 consecutive days 3-months in a row.

Those randomized to the FMD experienced greater weight loss and fat reduction, better blood sugar control, and lower inflammatory lab test scores.

These results seem to be in line with a recent randomized trial where more than 70 subjects completed three 5-day cycles of FMD. Researchers concluded that FMD was associated with better BMI, blood pressure, cholesterol levels, fasting blood sugars, and inflammatory lab results.

While the available research is promising, we are unable to conclude as to whether these effects are sustainable without long-term data.

Is ProLon Safe?

Prolon’s plant-based foods are free of additives and intended to provide the nourishment your body needs while you “fast”, though this doesn’t mean that the program is free of risks.

The previously mentioned studies mentioned that only mild adverse effects occurred with FMD, though they did not specify what these were.

While fasting may be associated with many health benefits, it is not safe for everybody.

For example, fasting can be dangerous in diabetics and those that have challenges controlling blood sugar as it can cause unsafe drops in glucose levels. If you’re on a medication that suggests consumption with food, fasting may negatively impact how it works.

Kids, pregnant women, and other metabolically challenging states like wound healing require more calories and nutrients than are available when fasting. If you have a history of an eating disorder or are considered underweight, you should avoid fasting.

For these reasons, speak with your doctor to determine if ProLon or other fasting regimens are safe for you.

The Cost

Prolon’s meal boxes include 5 meals, 1 for each day, and they always ship free. You can get your ProLon directly from their website.

The purchasing options include:


For one-time purchases, you’ll pay $249/box when you buy 1 or 2 boxes. If you opt for 3 or more, you’ll pay $225/box.


ProLon also offers a subscription service. You can set the delivery frequency at once every 1, 2, 3, 4, or 6-months and you’ll always pay $225/box.

It’s important to note that while ProLon does offer refunds, they only honor the return of unopened packages. Also, there is a $50 restocking fee/box, whether it was a single-order or subscription purpose.

For additional inquiries, contact support at or 888-618-1281.

What Are the Alternatives to ProLon?

Our research did not identify similar products that offer plant-based, prepackaged FMD foods. For the time being, it seems as though ProLon has cornered the market in this regard.

We were able to dig up several websites providing guides to help you “mimic” the FMD offered through ProLon’s prepackaged foods.

These entities essentially build their grocery list around the guidelines used in the previously mentioned research study.

Per the human trial portion of the study, the fasting-mimicking diet includes 5 consecutive days each month in which you adopt the following:

General Guidelines

  • The diet is plant-based, low protein, and low carb.
  • Obtain 30-50% of the RDA for vitamins, minerals, and fats
  • Carbs should primarily be complex (no sugary, processed foods).
  • Get healthy fats from sources like coconut oil, olive oil, nuts, etc.

Day 1

  • Limit sugar intake to <30g.
  • Your caloric intake should range from 4.5-7 kcal/lb of body weight (10% protein, 56% fat, 34% carbs)

Days 2-5

  • Limit sugar intake to <20g.
  • Your caloric intake should range from 3-5 kcal/lb of body weight (9% protein, 44% fat, 47% carbs)

Considering the cost of purchasing just 5 meals from ProLon, trying your luck at the local grocer is an easy way to spend just pennies on the dollar. Thus, this represents a much more cost-effective option.

The Bottom Line

ProLon tricks your body into believing it is in a fasted state by providing low calorie, nutrient-dense meals. Their methods have been successfully put to the test in a clinical study that delivered results comparable to those in other studies.

These studies demonstrated only short-term success, however. Long-term research is currently lacking. Thus data describing the sustainability of the benefits associated with FMD are still needed.

Though ProLon may be effective, it is quite expensive. You may be able to save a considerable portion of what you would pay for their products by following the FMP guidelines and shopping at your local grocer.

Fasting is not for everyone, however. Speak with your healthcare provider about ProLon to determine if fasting is right for you.

Customer Reviews

Start your review of ProLon:
  • 20 Customer Reviews
  • 35% Recommend This Company
2.6 out of 5
5 star: 30% 4 star: 0% 3 star: 10% 2 star: 15% 1 star: 45%

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  • Beware!

    Overall Experience:

    I ordered one circle, as they said each circle contained 5 boxes. I believed the price was decent for a 5-month supply.

    When I received the package, I thought it appeared small, but in fact, one circle has 5 boxes, one box PER DAY. I immediately asked for a refund, but ProLon refused to refund me under the pretense "I opened the seal in the box." I escalated this to PayPal but have not gotten back anything.

    ProLon is a scam as they ignore consumers rights.

    Bottom Line: No, I would not recommend this to a friend

  • Doesn’t work

    • By M C.,
    • Austin, TX,
    • May 30, 2018
    • Verified Reviewer
    Overall Experience:

    I just finished my first go with the ‘starvation box,’ and if you can believe it, I gained 2 lbs by the end of it. I normally fast once a week for religious reasons, so I wonder if intermittent fasting does not any have the same effect on someone who can tolerate a 24-hour fast. I maintained my normal (rigorous) workout routine with no issue. In conclusion, I’m frustrated that I wasted $250 and my energy on this useless plan.

    Bottom Line: No, I would not recommend this to a friend

  • No results on ProLon

    • By Melanie T.,
    • New Mexico,
    • Aug 4, 2018
    • Verified Reviewer
    Overall Experience:

    I have about 15 lbs to lose and have tried all there is to try. I followed the ProLon FMD to the letter for five days. Prior to starting ProLon, my fasting blood sugar was 80. After sticking with the 5-day meal plan, on day 6, my blood sugar was 88. Prior to starting ProLon my Blood Ketones read .9. After ProLon, my Ketones actually went down to .5. I did not lose an ounce, after 5 days of basically a high carb, calorie restricted diet. No inches lost either as I measured before and after the 5 day diet. I think this was really expensive for no results. As usual, the hype over this diet was not true. I feel like it was wasted money. I will not be recommending this to my patients. Nor will I invest this kind of time and money again.

    Bottom Line: No, I would not recommend this to a friend

  • Unhealthy, not effective and expensive!

    • By Chris L.,
    • Alabama,
    • Sep 9, 2018
    • Verified Reviewer
    Overall Experience:

    This seems to be somewhat of a scam. First of all, the price of close to $300 is ridicules for five-day fast. Given the fact you get powdered soup bags for lunch and dinner as four snack bags of olives (each containing 10 olives), two fish oil pills, two vitamins, and three glyceryl liquid. Oh and then there is the high sugar high carb "L-bars" for breakfast.

    I am 100% for fasting. I think fasting is fantastic and can clean.

    Some of us may need help and there are multiple other resources out there that are more effective and affordable (or even try using the foods around your home).

    But this product not only is it unhealthy, after the diet it recommends high carb diets that are are known to be unhealthy. Their goal is to sell you their nicely packaged product that I am sure it is marked up 300%.

    Bottom Line: No, I would not recommend this to a friend

  • Not for everyone!

    • By Deborah B.,
    • Georgia,
    • Sep 18, 2018
    • Verified Reviewer
    Overall Experience:

    I did the entire 5-day ProLon diet to the letter. I lost 3 lbs. The diet is incredibly salty, which I'm guessing is needed during a fast. I will say that I did experience an energy burst on day 4 and 5, but it came at a very high price. I could not sleep at all while on the diet, the joint pain I experienced while on the diet and for days afterward was intense. I also had a horrible eczema flare up, as the diet is not derived of anti-inflammatory ingredients at all. So I as mentioned in my title, this diet might work for some, but definitely not for the masses. I would not spend money on another cycle. I'm still trying to undo the damage it created in my body.

    Bottom Line: No, I would not recommend this to a friend

  • Not worth it for a variety of reasons!

    • By Kae T.,
    • Signal Mountain, TN,
    • Oct 3, 2018
    • Verified Reviewer
    Overall Experience:

    I am in my late 60's, very healthy, wanted to try this to see if it would reset my metabolism. I've fasted for 40 years, so used to it in all forms.

    The actual fast was easy; however, there are a few things that you should be aware of.

    First, it is extremely expensive, and in my opinion, definitely not worth what you get in any way, shape or form.

    Second, I started without any physical problems; healthy in mind and body. On day two I started getting joint aches and pains, by day four I felt like I had arthritis throughout my body, and by day five I got heart palpitations!

    Loads of support BEFORE and absolutely nothing afterwards from them.

    I'm a retired naturopath, so immediately loaded up on nutrients and some herbs. It took me three days to get back to no problems, but the experience left me very upset as I highly value my health.

    Be aware. Check other reviews as you will only see good ones on their site! I would recommend going on Amazon and checking out (by their reviews) some of the excellent fasting books out there instead of wasting your time, money and health on this!

    Bottom Line: No, I would not recommend this to a friend

  • Silly

    • By Peter J.,
    • Boston, MA,
    • Nov 20, 2018
    • Verified Reviewer
    Overall Experience:

    If you enjoy feeling ravenous and dull-witted, this diet is for you.

    Seriously, it was a dreadful week that ended on Day 6, when I ate everything in sight and regained whatever pounds I’d lost in a few days.

    Basically, you pay $250 for a half dozen packages of dried soup mix, some chewy bars, and herb tea.

    Overall, a perfectly ludicrous waste of time and money.

    Bottom Line: No, I would not recommend this to a friend

  • Rip off

    • By Sabina J.,
    • New York City, NY,
    • Jan 20, 2019
    • Verified Reviewer
    Overall Experience:

    One of the reasons the weight loss business doesn't advocate fasting is because they can't make more money on people eating less. It seems like ProLon has found a way to hack that "problem." Fast-mimicking boxes contain food-mimicking packets. I have real veg with olive oil instead. ProLon calorie intake is 1100 day 1 and 800 days 2-5. With that knowledge and for next to nothing, you can mimic the mimicking diet.

    Bottom Line: No, I would not recommend this to a friend

  • Too expensive and unwanted side effects

    • By Janet A.,
    • Philadelphia, PA,
    • Oct 28, 2019
    • Verified Reviewer
    Overall Experience:

    In addition to not being terribly effective or causing any weight loss, thus duet gave me aches and pains and heart palpitations. The piece of $250 is also absurdly expensive for the bars, soup mixes, and tea. I noticed a distinct worsening of my health during this program, and no weight loss. Ditto for my boyfriend who also tried it.

    Bottom Line: No, I would not recommend this to a friend

  • Not impressed

    • By Paola M.,
    • Los Angeles, CA,
    • Sep 25, 2018
    • Verified Reviewer
    Overall Experience:

    I've just finished my five-day ProLon Dietary plan.


    - Feeling lighter (lost 2 pounds).

    - Food tasted much better than expected.

    - No constipation (which I would've expected on such a low cal diet).


    - Lost of energy.

    - Felt hungry.

    - Fatigue during the day.

    - Expensive.

    - Not feeling a huge difference.

    - Felt dizzy during the day (not in the morning though!).

    If it would've been cheaper, I probably would like to try it again in three weeks to see if I would feel differently, but it's way too expensive for what it is!


    Bottom Line: No, I would not recommend this to a friend

  • Not worth the money

    • By Jane C.,
    • Rochester, NY,
    • Jan 26, 2019
    • Verified Reviewer
    Overall Experience:

    I just finished and it didn't really live up to my expectations. I look thinner and lost a couple of pounds, but of course, that's going to happen when you restrict calories and don't eat sugar for five days. The food was OK...bars are bars, dinner soups were decent, lunch soups eh.

    On days 4 and 5 ProLon says most people feel less hungry, an energy surge and increase and mental clarity...I did not experience this, and in fact felt extra hungry and tired on day 5 and could not focus on anything!

    On top of that, customer service told me originally that I could get a replacement for the tomato soup if I wrote it in the order notes (which I did). The box came with three tomato soup packages. I emailed customer service and they said they would overnight them. However, that was three days ago and they're still not here.

    I didn't get blood work or anything to measure results other than how I look and feel, and this is also being written right after completing the diet, so I don't have an opinion on any lasting effects yet. But after looking more into the allowed substitutions and calorie and nutrient breakdowns, I think you could recreate this yourself without wasting the money and have better food.

    Bottom Line: No, I would not recommend this to a friend

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