I’ve been fascinated by the myriad, wonderful benefits of fasting and have been pouring over the research for a few weeks now. But fasting is a big commitment. After all, you don’t eat. But now there’s a way to get all the benefits of fasting while still staying nourished, and it’s less stressful for you and your body. And the coolest thing of all is that one loses body fat but retains (and in some cases, gains) muscle mass. AND the results continue after you break the fast. That’s awesome, because traditional water fasts may cause muscle loss.

Enter the fasting mimicking diet.

The pioneer here is the Prolon Fasting Mimicking Diet, a 5 day plant-based program (they provide all the food you need) that mimics the benefits of fasting, yet you still eat. It’s a reduced calorie but nutrient rich diet; there’s food!

Prolon in particular is a proprietary mixture of micro and macronutrients that work together to put your body into a fasting state while nourishing you for a safer (than water-only) fast that also helps maintain energy levels. It’s similar to the benefits of ketosis, where your body burns fat for fuel, which is also a great way to remove toxins that are stored in fat cells. You’re meant to do several rounds depending on your goals and health status.

In a clinical study of participants who completed a 5-day ProLon cycle once a month for three months, the average weight loss at the end of the study was about 5.1 pounds. This was primarily abdominal fat, while lean body mass was preserved. Health benefits are sustained up to three ​months after completing 3 cycles of ProLon.

Before we get into all that, here are some benefits of fasting: (source)

• increased lifespan
• weight loss, fat loss
• autophagy (cellular cleanup of waste products, precancerous/abnormal cells)
• increased fat burning
• stem cell rejuvenation, cell regeneration
• better energy, sleep, and focus
• clear skin
• increased resistance to stress
• strengthen immune health
• improvement in inflammatory markers, lipids, blood pressure, blood glucose levels
• disease prevention, especially cancer, diabetes, heart disease

• A Better Relationship with Food: Support for overcoming stress eating. ProLon users report less cravings, eating smaller portions, and feeling more in control of what they eat after completing ProLon.
• Weight Loss: Targeting stubborn belly fat while maintaining lean body mass.
• Cellular Rejuvenation: Enhance autophagy (the clean-up of old, worn-out cells).
• Performance: users report more energy and focus.
• Healthy Aging: Brought on by weight loss, metabolic balance and healthier eating

Prolon is the first and only meal program that has gone through clinical trials at the University of Southern California and been patented for its anti-aging effects. Even better, stem cell-based rejuvenation continues for 2-3 days once you complete the program. Prolonged fasting forces the body to use stores of glucose, fat, and ketones, but it also breaks down a significant portion of white blood cells. During each cycle of fasting, this depletion of white blood cells induces changes that trigger stem cell-based regeneration of new immune system cells.

Best of all, the fat loss and benefits gained during the program are retained, especially if you complete several cycles.

You can read all about it on their website (<— click here).
NOTE: Prolon did not ask me to review this kit nor did they give me anything at a discount. I paid full price and chose to do the program myself.

First you order the kit. Mine was delivered quickly, and it has all your food, drinks, and supplements separated into daily boxes. You get information and a “meal guide” of sorts that tells you what to eat when. It’s all very clearly laid out and well packaged. Examples of the meals include nut-based bars, olives, soups, kale crackers, fasting support teas, and a special fasting beverage. Supplements are also included.

I picked a week when I know I don’t have a lot going on in terms of highly demanding activities or social events so I don’t have to resist delicious food. Regardless, it would be super easy to do this if you travel a lot or work a lot. It’s designed for busy people.

Why Am I Doing This?

Mostly I’m curious about the benefits, especially immune health (a 3-day water fast is proven to completely rebuild your immune system, though ProLon does not claim as much). I am always looking to boost health, and I would be lying if I wasn’t psyched for some fat loss. I’ve gained 4-5 pounds in the past year (likely due to my sensitive thyroid + stress) that I haven’t been able to shed. I’m 5’8″ and weigh 145 but am most comfortable around 140.

Let’s go!

Day One

My boyfriend made nachos and chocolate chip cookies the day before, and they’re basically the first things I see as I go upstairs to the kitchen on the first morning, a Monday. Normally I wouldn’t care about such things (we tend to eat differently), but having food be “off limits” seems triggering in some way. I don’t have a problem resisting, but for some reason it’s annoying.

I’m both slightly nervous for whatever reason and excited, but I’m not psyched about living off packaged foods for the week. But, it’s mostly organic, and it’s gluten and dairy free as well with no genetically modified ingredients. I also feel a bit sad that exercise is discouraged. I enjoy my burst training and trail running, as exercise is one of the things that keeps me sane. But I decide that leisurely hikes with the dogs will have to suffice.

I normally practice intermittent fasting and often don’t eat breakfast til 9 or even 10am. I’m not a coffee drinker, but I do love my green tea and have some of that to start the day (they discourage caffeine, but black coffee and 1 cup of caffeinated tea is OK).

I start off with the first breakfast: a 260 calorie, plant-based protein bar that contains 22 grams of fat and 5 grams of protein. I forget to savor it and remind myself to do so in the future. I silently hope that the fat and fiber (5 grams) will keep me full til lunch. It’s mostly nut based, macadamia, almonds, pecans, coconut products. It’s pretty good, but I’m starving two hours later. I drink tea and sulk.

Lunch was very filling: kale crackers, olives, and tomato soup (I don’t like tomato soup to begin with, but this isn’t bad). It keeps me filled for several hours. I have more tea. I drink a lot of water. I get another nut bar snack around 3. In general I feel fine, but it is only day 1 after all. The food is good.

Mostly it occurs to me, since I am not doing it on this day, how often I tend to grab bites of things, like a square of dark chocolate here, handful of nuts there. I don’t consider myself a grazer, but I’m kinda bummed that I don’t get my dark chocolate. I try to stay out of the fridge and pantry (don’t need to go in there anyhow since everything is provided for you in the box and doesn’t need refrigeration). Keep reminding myself that I can do anything for five days, but it seems like it’s gonna be a loooong week.

Dinner was a tasty Minestrone soup (130 calories, probably less than even any snack I’d eat). I added black pepper and garlic powder to spice it up a bit and ate the tiny “dessert” square before the soup.

Basically I drink 5 cups of tea to stay busy even though I don’t feel terribly hungry on this day. I have a typical Monday night reading the Prolon founder’s book about longevity, which is actually really good. It’s called The Longevity Diet: Discover the New Science Behind Stem Cell Activation and Regeneration to Slow Aging, Fight Disease, and Optimize Weight. Check it out here.

All in all the day’s calories total a little over 1,000. But it gets harder as the week goes on.

Day Two

I sleep normally (but I’m always a pretty good sleeper) and wake up feeling normal. As I wake up, have tea, and move around, I start to feel a bit weak and slightly famished, so I eat my breakfast bar and hope for the best. It works, and I feel better. There’s also a plant-based 32 ounce drink I have to drink today and for the remaining days, and when mixed with the hibiscus tea that’s offered, it’s pretty good. I decide to go out and vote while I still have the energy (it’s midterm elections day).

The usual soups and olives follow, and I get fairly grumpy, fatigued, and unable to focus well as the day progresses. I chill and do some light work and read.

Day Three

Again I sleep well. I wake up feeling pretty OK, braced for what many people call the worst day. I feel a little weak, so I decide to have a shot of electrolytes (my intervention, not recommended on the plan). My clothes feel looser. Today I savor the shit out of my breakfast bar because this is the day with the least amount of food.

I need a nap midday and wake up feeling awesome afterwards. I power out some work and take the dogs for another short walk. The hunger pangs have disappeared, and I have teas and my soup for dinner and another fairly uneventful, normal evening. I get a lot of accomplished and have crystal clear thinking on the work projects I’ve been procrastinating.

Day Four

I stay up too late watching Friday Night Lights (Texas forever!) and don’t sleep well for various reasons (snoring boyfriend). I don’t wake up feeling awesome, and I kind of dread more of the same food. I’m not hungry though, just irritated, and I feel kinda weak. I’ve pushed past the huger pang phase and assume I am in ketosis– fat burning mode. I choke down the breakfast bar, and nothing seems appetizing. I’m mad that the dog is begging for whatever little food I’m allotted.

I do a short hike with the four-leggeds and feel vaguely sluggish for the rest of the day but still pretty sharp mentally. I can’t even finish my soup lunch, but I do love those olives. I can’t finish the dinner soup either. I take a bath and have a mellow and somewhat unproductive evening.

Day Five

Again I didn’t get enough sleep, but I awake feeling much better than the previous day. I feel lighter and calmer, but due to 2 nights of less than ideal sleep, I do not feel amazing. My appetite seems slashed in half, for better or worse, and I’m really looking forward to fresh food tomorrow.

Not gonna lie, another day of the same food seems like a slog. But I’m super productive and record videos for my upcoming candida course for a few hours. I take the dogs on a couple of 20 minute hikes in the woods.

I spend the evening reading more of the Prolon founder’s longevity book and learn a lot more about the amazing benefits of fasting mimicking in cancer treatment, diabetes, cardiovascular disease, arthritis, and more, plus his recommendation for a longterm longevity diet (similar to the Blue Zone diet). It’s all really compelling, but I don’t agree with the amount of whole grains and cereals he recommends.

Day Six: Transition Day

My Prolon email tip of the day comes in today: “Congratulations! You have finished! You should be very proud of your accomplishment. You have given your body the gift of rejuvenation.” And certainly that has what’s kept me going throughout the week. My stem cells better be all shiny, and my immune system poised for flu season.

I am down four pounds and feeling good about shedding the few I have gained in the past few months. I’m back down to 140. We’ll see how long it stays off (UPDATE: it has stayed off 6+ months later). Prolon states that unlike water fasting or extreme diets, you burn fat and preserve muscle. I’m excited to get back to exercising as normal again too.

I feel good and energetic and SO PSYCHED TO BE BACK TO MY REGULAR DIET, which is similar to the longevity diet he recommends with less grains. I do eat meat daily, though chicken or fish, rarely red meat. Lots of veggies!

My first meal is scrambled eggs (because that is what my boyfriend made for breakfast), 1/2 cup of lentil stew, and green juice. I skip off to the store to buy ingredients for the chicken-garlic-kale stew I’ve been dreaming about making all week. The recs say to transition slowly back to your normal diet with soups and small portions of fish, chicken, and rice today, then you can eat as you normally do by day 7.

Afterthoughts & TMI Poop Talk

Reintegrating into real life food again–ahhhhh fresh, green vegetables!– I notice that I eat much more slowly and savor every bite rather than plowing through my meals like I normally do. My senses even seem heightened. My thinking is clearer. I get full on smaller portions and enjoy food more. I eat well already, but I do have a tendency to overindulge on sugar, and just about everything really, and this “fast” served as a good reset both physically and mentally. This program would be a great reset for people who tend to overeat.

I also notice I eat much more mindfully. I tend to grab bites of things here and there throughout the day, and when forced to refraining from those habits, it becomes clear just how often I mindlessly wander to the fridge when I’m procrastinating. I preach to my clients that grazing throughout the day raises insulin (something you do not want) and isn’t generally best for digestion and fat loss. I realize, even though I am only grabbing bites here and there– that I’m not eating as mindfully overall as I’d like.

Although this program is easy to follow on paper– it’s very well organized and easily laid out for you day to day–mentally, it may be very tough for some individuals, especially if you have a history of eating disorders, restriction, or bingeing. I am pretty strict about following programs, but at times I wanted to give up, and the five days seemed interminable. I was irritable on and off. The food was indeed tasty, but I was beyond sick of it by day five, and I desperately missed making fresh food and being able to exercise (some people may enjoy those perks though!). I didn’t miss meat at all, but I’m not a huge meat eater (I do feel better with animal protein, though, no doubt). What kept me going was focusing on the positive effects that fast mimicking was having on my body. Interestingly enough, I had zero cravings for anything during the five days.

Being a nutritionist, I love talking about poop, and fasting definitely changes your output. Most of this diet is liquid soups, so that can result in constipation for some or soft poops for others. It depends on your microbiome. But this is a mostly allergen-free diet (no meat, eggs, gluten, dairy), so many people notice a reduction in bloating, stuffy nose (typically caused by dairy), joint pain, and general GI issues.

Personally, my stomach rumbled pretty much constantly and I noticed more gas than usual (it immediately subsided when I stopped the program). Stool definitely changed consistency. Though not officially recommended, I took probiotics throughout the program to support digestion, and that helped regularity.

Who Should Do This Program

This program is perfect for anyone who has metabolic syndrome: high cholesterol, high blood glucose, high triglycerides, high CRP (inflammatory marker), high insulin. Or if you have excess abdominal fat or weight and you feel sluggish. Great if you have prediabetes; they claim the program will reverse it after 3 rounds. NOT OK if you’re on insulin. Good for cardiovascular disease or those with high risk factors for that and cancer. There’s even promising research that fasting before and after chemo can protect your cells and boost the effectiveness.

Even if you’re healthy, the benefits extend far beyond better numbers on your lab work: It’s basically a reset for your immune system and stimulates cellular cleanup. You’re essentially telling your body to take out the trash, hence the link to longevity. As you age, cellular waste accumulates and causes oxidation that creates free radical damage. That, in turn, increases cancer risk and accelerated aging.

Who Should Not Do This Program

Prolon has a long list of contraindications regarding who should avoid this program (underweight or sick people–unless under the care of a doctor–diabetics, people on certain meds, etc). As I’ve mentioned I don’t recommend this to people with disordered eating. The program does include grains and nightshades (a lot of tomatoes), so I’m not sure of the effects on those with, say, autoimmune (AI) disease. Nightshades can cause AI conditions to flare, but Prolon does claim it can be beneficial for AI conditions. One the one hand, reducing inflammation and resetting your system in this way is very beneficial for these populations, but I don’t think the food specifically caters to them.

I would also use caution for those with thyroid issues. I have hypothyroidism, and my thyroid numbers were skewed after I did this fast. I believe my thyroid was off prior to doing the program, though.

Also– you’re going to be hungry. It gets better, but you’ll be hungry at some point during the 5 days. It’s manageable but at times unpleasant. For me it went away by day three. Do not do this program if you have a full social calendar with dinners or a busy week. It is very easy for working people to complete, but you may get tired, irritable, and you don’t want to expend extra energy.

Final Word

I would highly recommend this program to anyone wanting to burn fat, boost brain power, and reset. This week I’m feeling much more grounded and productive. The program makes it easy to break out of binge cycles or sugar cravings and really helps to reset your ghrelin and leptin levels to regulate appetite. It’s also great for metabolic syndrome and anyone who has risk factors for cancer, heart disease, diabetes. I’d recommend reading the book for more info.

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