My Experience with the 5-Day Fasting Mimicking Diet
A couple months ago I was listening to an episode of the Kevin Rose Show with Dr. Valter Longo, Director of the Longevity Institute at USC. Here’s the description from the show notes:
Dr. Valter Longo is director of the Longevity Institute at USC and the Program on Longevity and Cancer at IFOM in Milan. In this podcast, we discuss Dr. Longo’s new book, The Longevity Diet, which is the culmination of 25 years of research on aging, nutrition, and disease across the globe.
Dr. Longo has put together a powerful combination of fasting and diet. The diet is that of centenarians (people living 100+ years) combined along with with the scientifically engineered 5-day fasting-mimicking diet (or FMD), done just 3-4 times a year. Dr. Longo designed the FMD after making a series of remarkable discoveries in mice, then in humans, indicating that specific micro-fasts can activate stem cells and promote regeneration and rejuvenation in multiple organs to significantly reduce the risk for diabetes, cancer, Alzheimer’s, and heart disease.
Fasting Mimicking Diet – Quick Overview
So quickly, what is the FMD?
In short, it’s a minimal calorie diet over the course of 5 days that mimics the results of an actual, zero-calorie fast.
Dr. Longo showed that these showed these minimal calorie diets had the similar regenerative and rejuvenating effects as the zero-calories fasts, opening the door to many people who may have otherwise been completely intimidated by 5 days of no food (like myself).
Like the title insinuates, you’re mimicking a “real” fast.
My 3 Favorite Benefits of Fasting
(including your cells eating themselves)
I’d always thought the only benefit of fasting was weight loss. No calories = pounds lost.
Makes sense. But while the weight loss is certainly part of the story, these studies have demonstrated some really amazing ancillary benefits including:
Benefit #1: Autophagy (when your cells eat themselves)
This is probably my new favorite phenomenon. Autophagy is when, during a time of nutrient stress (i.e. fasting), your cells start to use the less-optimal parts of themselves for energy and for building new parts.
Aka, they eat themselves! Or more specifically, they eat the less useful parts of themselves. What an amazing evolutionary adaptation! By fasting, you’re actually doing spring cleaning on the inside of every cell in your body. This has been linked to such wide-ranging benefits as improve conginitive functioning (see below), improved liver functioning, higher insulin sensitivity (a good thing) and improved body composition.
Japanese scientist Yoshinori Ohsumi actually won the 2016 Nobel prize in medicine for his work uncovering the details of this process.
Benefit #2: Improved Cognitive Function
Fasting has been related to increased cognitive energy and an increased ability to learn and handle stress. By refreshing your cells via autophagy, you’re keeping things fresh in a vital place where decreased autophagy has been correlated with diseases like Alzheimer’s.
On that note, there have also been studies linking calorie-restricted diets and intermittent fasting to reductions in the neural dysfunction that leads to Alzheimer’s, Parkinson’s and other neurodegenerative diseases.
Benefit #3: Cancer seems to hate it
A study by Dr. Longo showed that, in mice, the FMD in conjunction with chemotherapy has the potential to expose cancer cells to the immune system. There have also been previous studies demonstrating positive cancer responses using fasting alone as the treatment (again in mice, human trials will take years but the results look promising thus far).
Additionally, the regenerative properties discussed in Benefit #1 have been shown to play a huge role in helping subjects deal with the damaging effects chemotherapy can have on healthy cells.
Bonus Benefit (for me): Hangry no more
I’ve always eaten a lot and have been known to get, er, angry when I’m hungry. Some call it “hangry”. I would allow these negative emotions to completely overtake me and would be become generally unpleasant.
In experimenting with intermittent fasting (12-16 hour fasts; essentially skipping breakfast), I’ve experienced a dramatic reduction in these hangry states. I expect much of the same with this longer-term fast (albeit with perhaps a few ugly episodes in the first couple days).
There are more benefits that have been documented from fasting (slowing age markers, lower cholesterol, better digestive function) that I didn’t list here.
Mimicking the Fast Mimicking Diet
Dr. Longo offers an out-of-the-box solution for embarking on the FMD called ProLon. It costs $300 and nearly every review I’ve read has touted it as extremely effective. And while I have no reason to doubt this, I do have a problem paying $300 for an amount of food that would cost $35 at the grocery store.
Additionally, the internet is awash with smart people who have calculated the macro-nutrient breakdown from Dr. Longo’s original studies, enabling amateurs like me to mimic the FMD and create a relatively comparable experience.
The best documentation of someone mimicking the FMD was from Quantified Bob, which provided an incredible amount of quantified detail on his 5-day fast. I used this as a basis for my experiment.
Here’s the ideal daily calories intake (based on my body weight of 185 pounds):
Day 1 – 925 calories
Day 2-5 – 740 calories
The macro-nutrient breakdown from the original study:
Day 1 -10% protein, 56% fat, 34% carbs
Day 2-5 – 9% protein, 44% far, 47% carbs
So I went out and purchased my supplies for the week which included:
- 5 avocados (daily breakfast)
- 1 head of cauliflower
- 1 jar of Amazing Grass Green Superfood
- 1 jar of Beyond Raw Precision BCAAs (to offset lean muscle loss)
- 1 bag of raw, unsalted almonds
- 1 jar of coconut oil
- 2 small sweet potatoes
- 2 Fuji apples (which I would later deem a mistake)
- 1 bag of spinach
- 3-4 tsp of olive oil
That was pretty much it! And after a good meal on Sunday night, I was prepped for Day 1 of the Fasting Mimicking Diet.
Did I also mention that I’m giving up coffee during this 5 day stretch as well? Yeah, maybe not the best timing on that…
(At this point I’m just going to repost the notes I took throughout the process along with my body weight, body fat % readings as well as the actual number of calories I ate that day, broken out via MyFitnessPal)
Day 1 – 923 calories
7:25AM – Ate my AM meal of avocados and sea salt – feel great. Previous experimentation with intermittent fasting should allow me to make it past lunch without much of a hunger problem.
6:45PM – Had my dinner of Apple Almond Salad which, while seemed like a lot of food in volume, ended up being south of 400 calories which is quite a drop-off from my dinners which frequently top 1200 calories. (Note from end of experiment: eating an apple during this process was probably too many carbs – would definitely cut that out next time)
Day 2 – 775 calories
8:03AM – Workout complete, and wowza – could definitely feel the lack of calories throughout. Did a very abbreviated workout consisting of 2 sets of light kettlebell swings, goblet squats, bicep curls and exercise ball sit-ups – this after a good warm up and followed by good stretching. I was sipping on a drink containing 2 servings of greens powder mixed with 1 of BCAAs. Despite the fact that I could feel the early fatigue in my muscles, I’m really glad I did it. Feel refreshed and much more energized to take on the day than yesterday.
Day 3 – 760 calories
Day 4 – 761 calories
12:17PM – Spoke too soon on the hunger, it came back with a vengeance right about now. Granted I was home, near food where I’m usually gorging on a big, awesome lunch instead of my workspace where I could have sat with it and made it go away. But it is what it is. Had my lunch of a sweet potato (100g which is basically just a nub), a tablespoon of coconut oil and eight almonds.
Day 5 – 328 calories (half day)
FMD Results & Observations
Overall, I found the Fasting Mimicking Diet to be a challenging but doable endeavor. The main obstacle for me was the sluggishness I felt at some point on all the days; but who knows how much of that was the FMD and how much of that was caffeine withdrawal (again, probably not an ideal time to stop drinking coffee).
The tiny meals actually end up not being that big of a deal. Once you first through the first couple hunger pangs and watery mouths, the hunger becomes less and less of a consistent issue (although it does pop up with a vengeance from time-to-time).
There were a few instances (mostly on Day 3/4) where I had these amazing moments of clarity that resulted in some really quality work or personal insights. As I mentioned in my notes, I really did feel my body changing which I think had to contribute to these brief flashes of insight.
As for the two metrics I was tracking:
Body Weight: -5.3lbs (-1.06lbs/day)
Body Fat %: -2.4% (-.48%/day)
The body fat readings were done with a handheld Omron device at woefully inconsistent times and physical states (see Lessons for Next Time below) so while I have no doubt I lost body fat (I look leaner), I have no idea how accurate those numbers actually are.
I’m writing this recap 3 days after my fast has ended and my body weight is already back to 183.4lbs (granted, after a weekend of heavy eating and drinking…) which has helped alleviate my concerns about losing too much weight.
But in conclusion, I will absolutely be doing the Fasting Mimicking Diet again. It does require some effort, but the results of fasting are undeniable and well-worth the short-term discomfort.
Lessons for Next Time
There are several significant ways I’m going to improve my FMD when I take it on again in 3-4 months (Dr. Longo recommends it every quarter):
- Take measurements at more consistent times & physical state
- My body fat % was all over the place, most likely because of lack of consistency
- Get blood testing kit
- Interested to know what was happening in my blood (ketones, etc)
- Eat more fat, less carbs
- I realized that my macro-nutrient breakdown was skewed too much towards carbs in the first two days; plus I’d like to try and all but eliminate the carbs to really maximize the process
- Exercise regularly
- I’d be interested to see what keeping my normal workout plan would feel like, even if it’s not recommended.