3 Day Water Fast vs ProLon FMD

Here is a detailed review comparing my experience doing the ProLon Fasting Mimicking Diet (I’ve done it 3 times as of this update) and, water only fasting.

**3 day water fast vs ProLon FMD – updated April 2020**

We all get to a certain age when our bodies won’t put up with shenanigans anymore.  I’m there now, where my body is like a cranky headmistress at a boarding school, who won’t let even the slightest transgression slide.  Missing a little sleep, skipping a workout, an extra serving of bread or rice, a dessert or anything fried will all remind me I’ve been slack when I zip up my pants or step on the scale.  Does that mean I’ll never have a side of sweet potato fries or a double stuffed burrito again?  I’ve never claimed to be a saint.  But I do have some techniques that help me atone for my sins, like Intermittent Fasting and the ProLon Fasting Mimicking Diet.

I just did a 3 Day Water Only Fast.

Last week I took 3 days off to re-boot and did a 72-hour water only fast in Palm Springs.  I wanted to hit that 72-hour window to kick my body into a process called “autophagy” which is when your body goes into self-protection mode and starts cleaning up old, damaged cells.  It happens during fasting and takes approximately 3 days to get there.  However, there’s no test to see when your body goes into this phase.  But since it also takes the body approximately 72 hours to get into ketosis without exercise, so 3 days is general consensus in the fasting / longevity field.


I admit, water fasting is no picnic.  I felt very weak.  I couldn’t exercise except for walking my dogs.  My liquids included mineral water, electrolyte water, iced tea, green tea and black coffee.  I lost approximately 3.8 lbs and felt well rested, but water fasting is not a tactic I can pull off at regular intervals.  I didn’t do a body fat test before and after, so I can’t be sure how much of the loss was muscle and how much was fat.

3 day water only fast

6 hours to go on my 72 hour water-only fast

Soon I’ll be doing another round of the Fasting Mimicking Diet.

My other method for re-booting is the ProLon Fasting Mimicking Diet.  I’ll be doing another round soon.  I aim to do it twice a year.  This form of fasting has been clinically tested and patented for its anti-aging effects showing that it pushes the body into autophagy.  And like all fasts, it’s also used for weight loss and promoting overall health.


What is the Fasting Mimicking Diet all about?

The Fasting Mimicking Diet (FMD) was developed to get the same benefits as a water only fast, but with food for 5 days.  The specific foods and amounts were chosen to trick the body into thinking its fasting while preventing you from feeling like you’re starving.


This way you can still function in a way most people can’t when they’re water fasting.  You can do some exercise and even manage to go to work assuming you’re not doing a physically taxing job. Each day, the calories range from around 700 to 1,100.


After 25 years of research on aging and diseases, the inventor of the FMD, Dr. Valter Longo, believes one key to longevity lies in a moderate protein, Mediterranean-style diet.  The foods used in the FMD are vegetarian, high in polyunsaturated fat and, low in protein and carbs so the body’s nutrient sensing pathways aren’t triggered.  This makes the body think it’s in fasting mode.


Weight loss is probably the most popular reason the people I know do this diet.  For me, it’s mostly about the cellular rejuvenation and kicking cravings for sweets and starches.  Although each time I’ve done it, I’ve lost almost 4 lbs. in those 5 days.  Because of the food in the FMD, it’s mostly fat that is lost, not muscle.  And according to the clinical studies done by the University of Southern California and the NIH, the fat lost is mostly from the belly.


How Much Weight Can I Lost on the FMD?

The volunteers in the clinical trial followed the FMD for 3 months, while volunteers in the control group didn’t change their eating habits. The results showed the people on the FMD lost an average of 5 lbs. of fat and 1.2 inches around the waist, while preserving lean body mass.  The volunteers not on the FMD saw no change.


Let me clarify.  When I say the participants did the diet for 3 months, that means they ate the food provided in the ProLon kit for 5 days and ate what they wanted for the rest of the month.  Then they repeated this cycle 2 more times.


Remember these weight loss numbers are averages.  I’ve had male clients do the FMD and lose over 7 lbs, but they also ate a healthy diet the rest of the time.  So if you watch what you’re eating the rest of the month, you can do better than the test subjects.


Here’s an example of how to do it…

May: Follow the diet for 5 consecutive days in May, (i.e. May 1 – 5), then eat as normal for the rest of the month.

June:  Repeat June 1 – 5, then eat as normal the rest of the month.

July: Repeat July 1 – 5, then eat as normal the rest of the month.

The benefits continue after you complete the cycle.

So it’s really just a 15 day diet, not a 3 month diet! 

Note:  if you’re just doing it for the anti-aging benefits, you can simply do it twice a year.

What about my metabolism?

If you’re wondering about the impact on your metabolism, worry no more.  There was a time when nutritionists and fitness enthusiasts thought that fasting would slow down metabolism.  This is only true of long terms fasts.  Studies have found the opposite to be true of short terms fasts like the FMD or a water only fast for 2 or 3 days.  One study of 11 men on a starvation fast for 3 days showed their metabolisms increased by up to 14%.  Much respect to those men.  Do you know how hard it is to get people to sign up for a starvation study??

Now for the all the goodness…

What benefits can I expect from the ProLon Fasting Mimicking Diet?

  • Decrease weight and body fat
  • Stem cell regeneration
  • Maintain glucose (blood sugar) at healthy levels
  • Maintain C reactive protein (a marker for inflammation) at healthy levels
  • Maintain triglycerides at healthy levels
  • Maintain blood pressure at healthy levels
  • Maintain healthy levels of bone density
  • Impact in IGF-1 (a marker for aging)
  • Maintain insulin resistance at healthy levels
  • Maintain cholesterol at healthy levels
  • Decrease visceral fat (the most dangerous kind found around the vital organs)


Everything you need to do the FMD comes in a box, pre-packaged and ready to go. That means there’s no need to go shopping, no fancy recipes and no hard to find ingredients.  Plus the food tastes good too.  Wait until you try the nut bars – yum!

ProLon gives you reset in just 5 days by providing the benefits of fasting without having to skip a meal!

Interested in seeing what it can do for you?  Click here:

FYI, here’s a shot from the last time I did ProLon – this was the halfway point.  It gets easier every time.  Some people like to do it at home, others like to do it when they’re traveling.

Fasting Mimicking Diet vs Water fast

Midway thru my last time on the ProLon FMD, results came fast.

After the first time I tried ProLon, I was a believer.

Some of the links above contain affiliate codes.  If you make a purchase through one of the links, I may receive a referral fee at no additional cost to you…. actually, you get a discount!

Jill Brown
Jill Brown
Hi, I'm JillI am a Los Angeles based Fitness + Nutrition Coach. With 20+ years of experience in teaching, training and continuing my education, I have transformed thousands of lives through fitness and healthy lifestyle changes.