Welcome to Nutrition Bites. The no nonsense podcast where you get the truth about food so you can eat what you want and be healthy. I’m your host Maggie and welcome to the series! Today’s topic was requested by a friend who informed me of a new fasting fad that’s all the rage in the New York City and TikTok influencer scene. So you know we have to talk about it. On the menu today, ProLon.
In early 2020 Gwenyth Paltrow launched a series on Netflix called The Goop Lab. A behind-the-scenes look at her company’s lifestyle and wellness office as they tested out the latest health trends. One of the episodes of this mini-series is all about longevity and healthy aging. Of course, it’s Goop so really it’s all about exploring ways to #biohack your way to eternal youth. In the episode, Dr. Valter Longo (PhD-kinda doctor..not medical doctor), introduces ProLon - a fasting nutrition program designed to “trigger rejuvenation and press the biological reset button”. Sounds ideal for Goop right? In the episode, ProLon is pitted against veganism and pescetarianism to see which one helps us age the healthiest. Now I’ll reveal the results of the showdown a little later, but first let’s learn more about this new fad diet. What is ProLon, and more importantly does it actually work?
Branded as the “fasting plan that lets you eat”, ProLon is a 5-day subscription dietary program that is designed to support healthy aging. Compared to more traditional fasting regimes where one goes many hours or a full day with no food, ProLon allows you to consume a small amount of calories every day of the diet. Around 1100 calories on Day 1, and 700-800 calories on each of the remaining 4 days. That’s equivalent to consuming roughly ⅓ - ¼ of an adult’s daily calorie need every day of the diet.. ProLon is based on the Fasting Mimicking Diet - a concept developed by Dr. Volter Longo, a prominent Italian researcher based out of the University of Southern California. According to Dr. Longo, he’s come up with a precise meal plan that lets you eat, albeit minimally, while your body thinks it’s fasting. Speaking of eating, all meals on the diet are provided in a package of daily boxes. Now if you’re picturing a Hello Fresh or similar meal-kit sized package, set those expectations on the floor. Each ProLon daily food box contains a small mix of items such as: a single nut bar, freeze-dried soups, kale crackers or olives, herbal teas, a low-cal beverage, and supplements to make sure you don’t get scurvy and die. These foods were chosen, or created, to be low in calories, low in protein and low in carbs.
Now, on paper this doesn’t sound completely terrible, but the fact that the ProLon website recommends drinking unlimited herbal tea, and chowing down on sugar free-gum to stave off hunger makes me wary of how satisfying these meals are. Not only that but they also provide tips on how to make the food taste better, including adding a squeeze of lemon to your soup. Although, as they hilariously point out, you’re not allowed to actually eat the lemon. Red flag #1.
Ok so that’s the basics of the diet covered - but what about the benefits? Well ProLon lists multiple promises including “ cellular renewal”, “better metabolic health” and “enhanced clarity and performance” - all key phrases in the modern-day wellness playbook. However, one of its most popular claims, and definitely central to its social media strategy, is weight loss. Although ProLon was not intended as a weight loss diet, the results of one clinical trial saw participants lose an average of 5 pounds, while maintaining their lean muscle mass. Of course, that weight loss only occurred after enduring the diet every month for 3 months in a row.
And although this is an attractive outcome for many people, ProLon’s marketing focus is on something a little more magical - what they call rejuvenation. The word rejuvenation is often used in skincare but in the case of ProLon it’s an inward focus. More specifically, supporting the body’s natural process of cellular clean-up. Now the scientific term for this rejuvenation action is called “autophagy” which literally means self eating. As scary as it sounds, it’s not something to make a budget horror film about. Autophagy is a routine cell death that encourages healthy cell turnover so we have fresh new cells in our body instead of crickety old ones. This is important when we think of aging. Many biological issues with growing old, whether it’s the development of diabetes or cancer, often arise when our aging, malfunctioning cells are not replaced in a timely manner. So theoretically, promoting autophagy could be a way to prevent or reduce health issues related to the natural aging process.Now for the fun part. Scientists think that fasting helps promote autophagy. The theory is that while our cells are not receiving nutrients, they ramp up the autophagy process. Think of it like the morning clean-up after a house party. You gotta take out the trash first before you sit down for breakfast. ProLon claims that cells enter into this cleaning mode as a protective reaction to limited incoming nutrients. Now in order for your cells to know whether they have access to nutrients or not they use something called “nutrient sensing pathways”. These are biochemical and molecular communication channels that let cells know the nutrient levels in the body. And this is where ProLon tries to differentiate itself. They claim that their precise food plan provides essential nutrients, but does not activate the cellular nutrient sensing pathways. In other words, it kind of deceives cells into thinking there are zero incoming nutrients, and therefore they should trigger autophagy. A pretty remarkable accomplishment, if it’s true.
But here’s where my skepticism kicks in. Everytime a diet or supplement claims to “trick” our body it’s either false advertising or something that will make you shit your pants. Many fad diets use vague scientific language to make hefty claims. But ProLon has the advantage of being created by an established scientist who has conducted 20 years of research on nutrient sensing and fasting. So what does the science behind ProLon actually show?
Well as much as their website promotes its science-backed formula it’s actually really difficult to find the exact studies that helped launch this Fasting Mimicking Diet. In fact, on their FAQ there is a question about access to the research papers and their response is to get in touch with their customer service department who will connect you to a Medical Science Liaison. And maybe, just maybe, they will send you a copy of the studies. So much for transparency.
Fortunately, I love a good internet quest, and after digging through the janky website of ProLon’s parent company, I found some scientific papers. Ready for the big reveal? Unsurprisingly to skeptical ol’ me, the vast majority of research on the Fasting Mimicking Diet (or FMD) is pre-clinical. This means researchers did experiments on cells in petri dishes or on animals, like mice. In nutrition science these are important experiments to build a hypothesis, but you simply can not draw conclusions that apply to humans based on preclinical results. Our bodies are far more complicated than a clump of cells or a teensy rodent. Another critique with the science here is that the majority was conducted in cancer patients, which isn’t surprising as caloric restriction is a big area of focus for potential cancer treatment. But those who are interested in ProLon likely won’t have cancer or any disease for that matter. And from what I can find, only one trial on FMD has been conducted on healthy people.
This small study of less than 100 individuals investigated differences in risk factors for age-related diseases. Risk factors include things like body weight, blood pressure and cholesterol levels. Now this clinical trial compared a group of individuals who underwent the 5-day FMD every month for 3 consecutive months vs. a group who ate as they normally would. And the results were pretty predictable - those who completed FMD lost a bit of weight and those who ate normally, stayed the same. This outcome makes total sense considering that for ¼ of the month the FMD group ate significantly less food than normal. Interestingly, other than weight loss, there weren’t many changes in any of the other risk factors. So their whole “healthy aging” claim is a bit suspicious. Another really important point to bring up about this study is the conflict of interest. Dr. Longo was a researcher on this clinical trial, however this study was also sponsored by the parent company of ProLon, which Dr. Longo and the University of Southern California have a financial stake in. Even though the paper notes that Dr. Longo was not involved in collecting or analyzing data, I can’t overlook the fact that there’s a lot riding on ensuring the outcomes of this trial seem spectacular- at least for marketing purposes. Conflict of interest aside, the fact remains that ProLon only has one, small, study to its name that tests their longevity diet in a sample of healthy individuals. And they didn’t even really show that subjects aged any healthier. Which brings us back to Goop.
As I introduced earlier, the Goop Lab aging episode focused on how to age healthier through inward changes. So, they devised a mini experiment testing if the ProLon diet, the vegan diet, or the pescatarian diet (which is a vegetarian diet where you can eat fish and seafood) could make us inwardly any younger. Three Goopers, including the Queen G herself Ms. Gwenyth, took part in the experiment. Gwenyth followed ProLon for 5 days while two of her colleagues ate vegan or pescatarian for 3 weeks.
To figure out if these ways of eating impacted their age they took measurements of their biological age before and after the diet. Biological age is a number which represents how your body has aged health-wise. This is different from your chronological age which is the number of years and months you’ve spent rotating on Earth. For example, you could be chronologically 35, but biologically 30. To calculate biological age, the three Goopers had various health biomarkers measured and inputted into a mathematical algorithm. They discovered that at baseline, or before the diets, all 3 had slightly lower biological ages than their chronological age. Which is not surprising given their workplace. I mean I can genuinely imagine Goop HR subjecting them to a detox if they biologically scored older. After completing the diets, their biological age was calculated again and results showed that both the pescatarian diet and the ProLon diet lowered the biological age of the Goopers by over one year. Theoretically this meant their body became one year “younger”. Now this is a perfect sound bite for TV, but here’s why you shouldn’t trust these results. First, the way biological age was calculated is very new and rather experimental - so who knows if we can even trust this score. Secondly, there is so much variability with individual results - just because Gwenyth scored biologically younger after ProLon doesn’t mean you will. And thirdly, we have no idea how long this change even lasts for.
And that’s the biggest problem with ProLon - it’s not a long-term solution for healthy aging, weight loss, or any other alleged benefit. There’s just no evidence that the FMD is superior to any other fasting methods, or longevity diets (like pescetarianism) for that matter. Another considerable concern with FMD is the extremely low calorie count for 5 consecutive days. Eating ⅓ - ¼ of your daily energy needs for nearly a week can be problematic for anyone. But especially those with existing health issues, a history of disordered eating, or with bigger baseline energy needs.
Another prominent con of ProLon is the incredibly restrictive nature of the diet. Compared to Intermittent Fasting, which lets followers eat whatever they want but within a restricted time frame, ProLon is like being in food jail. Even Gwenyth Paltrow had no problem critiquing the crappy taste of the soups directly to Dr. Longo. One customer testimonial highlighted that the diet ended up making her like olives because “they taste amazing when that’s all you can eat in between your soups”. When you combine an uninspiring menu with extreme calorie restriction, hunger, annoyance, and difficulty sticking with the program will result. Many people, including Gwenyth, remarked how desperately they wanted the experience to be over - especially as they battled fatigue and difficulty sleeping. One customer remarked they regularly drank the olive juice because of how hungry they were. Even ProLon alludes to the difficulty of sticking with FMD by recommending a shortlist of foods to add to your diet as a last resort before giving up. But the list is pretty meager: “a slice or two of apple, one stalk of celery or one small Persian cucumber of 5 to 6 inches in length.” How very generous. Last but not least, the price of ProLon is also problematic. For the unreasonable cost of $249 USD you too can eat tiny amounts of flavorless food for 5 days.
While overall I think the problems with ProLon outweigh any benefits, in the spirit of trying to offer a more balanced perspective, here are some positives of this diet. FMD is a method that is backed by some science - although it’s more theoretical than fact at this point in time. That said, who knows what future research will show? Clinical trials take years to complete, and maybe in a decade science will show that FMD is a diet worth subscribing to. A more tangible pro of this diet is the short-term commitment required. After all, 5 days a month is a lot easier to stick with than a daily habit change for life. Additionally, the convenience of ProLon’s pre-set daily meals has also been noted as a big plus.
But despite these benefits, I still personally can’t shake the feeling that ProLon is merely a cash grab based off of a premature scientific concept. As I covered back in Episode 5 of the podcast, dietary fasting is an increasingly popular trend with many different forms and benefits. But the most common types of dietary fasting do not restrict your total caloric intake like ProLon does. Nor do they restrict what you are allowed to eat, which means you don’t have to grapple with guilt if you accidentally take a bite out of the lemon you were only meant to squeeze onto your soup. So if ProLon initially piqued your interest, I’d say forget about this expensive and uncomfortable experiment that really based their promises on unfair extrapolations from cellular and animal studies. Save yourself the stress and spend the money on something that will not make you desperately slurp olive juice out of hunger. Or if that’s your thing, at least get a bigger jar of olives.
That’s been the bite today. Stay hungry (but not too hungry).