My experience with the 5-day fast mimicking diet.
The Fast Mimicking Diet was developed by longevity researcher Dr. Valter Longo who serves as the director of the USC Longevity Institute.
Prolon, a company owned by Dr. Longo (although he claims he does not receive financial benefit from the company), sells ?fasting kits? which allow you to easily take part in a 5-day diet program by consuming their ?proprietary nut bars and soup blends?. The company describes the diet as so on their website:
??5-day dietary program that nourishes your body while promoting regenerative and rejuvenating changes, including effects on a wide range of markers that contribute to aging, such as cholesterol, inflammation, and fasting glucose.?
The goal of the diet is to place you in the metabolic state of fasting while mitigating the physical and psychological stress that fasting places on the body. The benefits of fasting and the studies conducted on the FMD in particular are out of the scope of this post but I?ll add some links at the end if you are interested.
Last year, I put myself through a 5-day water only fast and it was absolute hell. I had terrible heartburn, crazy mood swings, and crippling fatigue and muscle weakness. Consuming something, even if it was only 800 calories, sounded far better than going 5 days on an empty stomach. I didn?t want to spend upwards of $200 on a FMD kit from Prolon so I made one myself following the same parameters outlined in the studies conducted.
It worked out well. I saved a lot of money and was able to find a few snacks and food options that I?ve adopted into my normal diet.
Diet outlined in The Longevity Diet by Valter Longo
The diet was very simple to follow and I found it much easier than the water fast. Consuming at least a few calories each day allowed me to maintain energy and stay productive at work. I thought about food, but it didn?t consume me the way it did during my water fast.
Day One ? 1100 Calories
Skipped Breakfast. For lunch I had split pea soup and 0.5 cup of pistachios. For dinner I had 2 oz of unsalted almonds and a veggie soup mix. 5 Olives for a midnight snack.
How I felt: Completely fine. A little hungry when I went to bed but other than that I felt normal.
Day Two ? 800 Calories
Skipped Breakfast. For lunch I had Tuscan white bean soup. No snack. For dinner I had veggie soup mix and 5 olives.
How I felt: Hunger hit hard at lunch. By 3pm I?m really tired. I went home and fell asleep early. Those ketones need to kick in!
Day Three ? 800 Calories
Skipped Breakfast. For lunch I had 10 olives, 1/2 an avocado and a cup of steamed broccoli. For dinner I had minestrone soup with olive oil added.
How I felt: Tired and emotional in the morning. Things actually improve as the day goes on and I get a burst of energy in the evening, so much so that I hardly sleep all night.
Day Four ? 800 Calories
12 almonds for breakfast. For lunch I had roasted cauliflower soup and a cup of steamed brussel sprouts. For dinner I had half a cup of pistachios.
How I felt: A little tired due to lack of sleep. Tired mind feels sharper than expected. Hunger has gone away.
Day Five ? ~1000 Calories
I actually kind of cheated on day five. I should have consumed only 800 calories. I was planning on having a big meal that evening so I started a slow introduction and ate a light lunch.
What I tracked
My BP wasn?t really interesting, everything stayed stable as expected. I did notice an increase in my RHR which made sleep difficult at times (especially Tuesday night). My body wanted sleep but my heart rate was too high to allow me to relax.
Ketone and Blood Glucose Levels
La Croix is an essential supplement to the FMD
My Glucose levels initially declined steadily as my glycogen depleted and then stabilized in the early 80s (mg/dL). I?m sure I would have seen a further decrease had I cut my calories back even more. We see a huge jump on Friday evening as expected as I reintroduce carb-heavy food back into my diet. Ketone levels steadily increased as expected and maxed out at ~5 mmol/L. Once ketone levels are up past ~1.5 I usually feel a lot better. The worse zone to be in is low glucose and low ketone levels.
Yes that is my urine. Yes I drink out of those cups.
Body weight steadily declined over the course of the diet. I was surprised by how quickly I gained back the weight in the days after the fast. Losing weight wasn?t my goal so I was reckless with the number of calories I consumed post-fast. If your purpose is to lose a few pounds, I would recommend tracking your calories carefully after the diet and ensure you are eating a normal amount. I?m sure I consumed 4,000 to 5,000 calories/day in the days after my fast.
The FMD is a great alternative to fasting and I?m excited to see what role it will play in preventative healthcare and cancer treatment. I plan on adopting the program into my own diet and conducting a 5-day FMD 2x per year. I encourage you to check out the studies and articles below. In the modern world of Herbalife and ?alkaline diets?, it can be difficult to separate fad diets hiding behind good marketing and innovative approaches backed by science. Trust your doctor, trust the science, and stay open-minded.