ProLon Review: A Fasting Plan That Lets You Eat?

ProLon Review: A Fasting Plan That Lets You Eat?

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Disclaimer: None of the information in this article constitutes medical advice, and is just the opinion of the writer(s). We recommend that patients follow their doctor’s guidance in regard to weight loss and fasting.

ProLon is a fasting meal service, which sounds like an oxymoron. The brand describes their service as “the fasting plan that lets you eat.” The company also claims that their offering “is based on over 20 years of scientific research and over $34 million in R&D.”

In this article we’ll review a medical study on ProLon, along with the ingredients in their meals, to give our take on whether the plan is likely to be effective for weight loss and whether it's healthy or not.

We'll also share a real user review of ProLon.

Does ProLon Cause Weight Loss?

ProLon clinical efficacy claims

ProLon is a fasting-mimicking diet, and the brand claims it can cause 5.7 pounds of weight loss in 5 days.

Fasting-mimicking diets significantly reduce calorie and sugar intake to replicate the metabolic benefits of fasting. A clinical trial published in the Science Translational Medicine journal tested whether ProLon could cause weight loss.

Trial participants on the fasting-mimicking diet lost around 7 pounds over 3 months by using ProLon for 5 days of the month.

We will conclude from this research that ProLon is likely to be effective for weight loss. That being said, any diet that restricts calories below baseline can cause weight loss, and we don't consider this trial to be particularly well-designed because there is no comparison to another diet model such as intermittent fasting.

We commend ProLon for funding legitimate medical research, but we would not recommend their program based on these results alone. 

ProLon Ingredient Review

ProLon Nut Bar ingredients

ProLon has a Nutritional Fact Information page on their website with Nutrition Facts labels for all of their products. For the most part, their food products are sourced from whole foods ingredients and we would consider them to be healthy and nutritious.

The above ingredient label is from their "Nut Bar."

All of their soups are composed entirely of whole foods ingredients and we would recommend any of their soups from a nutritional perspective. The soups are formulated with a plant base like butternut squash, and contain spices such as oregano, garlic and chives.

ProLon snacks are also decently formulated, though there are some ingredients in their snacks we would recommend avoiding, such as cane sugar in their  fasting bar called “L-Bar” and citric acid in their Almond & Kale Crackers.

As detailed in a medical review published in the Toxicology Reports journal, citric acid is a food additive used as a flavor enhancer and preservative which is typically manufactured from a fungus, and which can cause significant whole-body inflammatory reactions in a small subset of the population. We don’t believe this ingredient is likely to have a negative effect on most consumers, but we recommend avoiding it generally as it has little nutritive value and appears to have some risk.

ProLon also has a Drinks section including custom drinks and teas. We would recommend any of their teas which are sourced exclusively from organic herbal tea ingredients. We would recommend avoiding their “L-Drink” which contains natural flavors

As we documented in our review of another nutritional brand called Pruvit, there is some medical research suggesting that natural flavoring agents may be harmful to human health, and since this is a catch-all term that doesn’t describe the exact chemical compounds used to create the flavor, we recommend avoiding foods and supplements containing this ingredient. The “L-Drink” also contains citric acid.

Overall we consider this meal plan healthier than most diet plans we've reviewed on Illuminate Health, but we would only recommend ProLon's soups and teas.

ProLon Real User Review

One of the most popular YouTube reviews of the ProLon diet is published by a channel called “Jason Sami.” The creator shares their experience and results on the ProLon diet, and the review appears to be unsponsored:

Is Fasting Healthy?

At this point in the review, readers are likely wondering whether fasting (rather than a "fasting-mimicking diet") is healthy, and whether it can cause weight loss. A medical review published in 2021 examined data from clinical trials on various types of fasting, from standard fasting to intermittent fasting to the “5:2 diet.” 

The researchers found that fasting had favorable effects on insulin resistance and blood pressure, and also caused weight loss in overweight and obese patients. 

As we explained in our DoFasting supplements reviews article, there is medical evidence that intermittent fasting causes weight loss irrespective of calories consumed, because of favorable metabolic changes. Fasting is a slight stressor to the body which can cause epigenetic changes that improve health. It’s also logical that the human body would be evolved to adapt to variable periods of fasting, because humans did not evolve with constant access to food.

Intermittent fasting, which refers to fasting for a fixed period of hours per day (typically 16), is effective for weight loss. A meta-study examined data from 27 individual trials on intermittent fasting and weight loss. In every single trial, participants lost weight. The amount of weight lost relative to baseline weight ranged from 0.8% to 13%, but the trials were all short in duration, ranging between 2 and 26 weeks. These are incredibly impressive results.

We would recommend that patients speak with a doctor prior to fasting, because it may not be safe for all people.

ProLon Vs. Other Diet Programs

ProLon isn't the only diet plan that's been studied in legitimate medical research. An extensive medical review published in 2016 examined the efficacy of commercial weight loss programs. The study authors reviewed data on Weight Watchers, Jenny Craig, Nutrisystem, MediFast and Optifast.

Jenny Craig was found to be the most effective weight loss program, with an average weight loss 4.9% greater than nutritional counseling alone over the course of one year. This equates to weight loss of 9 pounds for a 200 pound person.

We would consider ProLon likely to cause greater weight loss than Jenny Craig, given that ProLon caused weight loss of 7 pounds in three months, which equates to potentially annualized weight loss of 28 pounds.

We also consider ProLon to be healthier than Jenny Craig as it provides mostly whole foods ingredients and Jenny Craig meals are more highly processed.

Based on the existing research, we would recommend ProLon over other commercial diet programs.

Our Weight Loss Supplement Recommendations

There exist several weight loss supplements with significant clinical backing in terms of both efficacy and safety. These supplements are not a substitute for healthy diet, but may be used in conjunction with a healthy diet.

We recommend dietary fiber as a safe and effective weight loss supplement, especially when combined with caloric restriction.

landmark medical study found that moderate caloric restriction (750 calories per day below baseline) combined with dietary fiber intake (a minimum of 20 grams per day) caused an average weight loss of 16.03 pounds over 6 months. That’s a pace of 32 pounds per year of weight loss in overweight individuals simply by adding fiber to a moderately-restricted-calorie diet.

The fiber supplement we recommend is SuperGut Fiber Mix. It contains a clean and effective formulation: a blend of three different types of unflavored dietary fiber and zero additive ingredients. It can be mixed into liquids or foods. Interested consumers can buy SuperGut fiber at this link.

We recommend using two fiber mixes per day, which provides 16 grams (g) of total fiber. Diet should provide the remaining fiber necessary to meet the 20 g minimum threshold.

Medium-chain triglyceride (MCT) oil is another dietary supplement which has been shown in clinical trials to cause weight loss.

MCT oil is quickly absorbed by the body and increases metabolic rate, which causes fat loss. A meta-study on MCT oil documented weight loss of 1.12 pounds over 10 weeks. This equates to a potential annualized weight loss of 5.84 pounds with MCT oil supplementation.

We recommend Bulletproof MCT Oil as our top MCT oil product, because it has a clean and effective formulation. The only ingredient is MCT oil derived from coconuts, and the product has no questionable additives. Interested consumers can buy Bulletproof MCT Oil at this link.

The effective dose range of MCT oil for weight loss (based on the medical review) is 1.7 g to 10 g per day. Bulletproof's MCT oil provides 14 g in one tablespoon, so around two-thirds of one tablespoon should be a maximally-effective dosage.

ProLon Pros and Cons

Here’s our opinion of the pros and cons of the ProLon diet:


  • Healthy formulations
  • Fasting has metabolic benefits
  • Proven in a clinical trial to work
  • Better than other diet programs


  • Some products contain questionable additives
  • No proof of efficacy over regular fasting
Stay up-to-date on our research reviews


ProLon has published convincing medical evidence that the fasting-mimicking diet has similar metabolic benefits to fasting. The diet plan is proven to cause weight loss, and appears to be more effective and healthier than other commercial diet programs such as Nutrisystem and Jenny Craig.

We cannot identify any medical studies proving that ProLon is more effective than intermittent fasting, or than regular fasting, so we do not recommend the program overall. Their meal plans also contain a few additive ingredients that we recommend avoiding.

For consumers that are set on using a commercial diet program, we would recommend ProLon over the alternatives.

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