Prolon: The Ultimate 5-Day Cellular Reset That Triggers Autophagy

I’ve been getting up the nerve to try this for a while now, and I figured the best way to commit was to turn it into a blog. That, and the fact that one of my friends has now done Prolon five times—which kind of pushed me to finally go for it.

What Is Prolon?

Prolon is a five-day fasting-mimicking diet system developed by Valter Longo, whose studies on both mice and humans found that keeping the body just under a certain nutrient threshold (while still eating a small amount of food each day) can actually trigger fasting mode. (Read my blog on his book: here.) The idea is that your body gets many of the same benefits as a water fast—like autophagy (your body’s way of cleaning out damaged cells and cellular junk to make room for fresh, new and rejuvenated cells) and a metabolic reset—but with fewer hunger pangs and less risk of muscle or bone loss.

Why Prolon Might Be Better Than a Water Fast

In fact, Longo argues it may be even better than a water fast. With Prolon, you’re still getting key nutrients over those five days, which supports your body instead of completely stressing it, and, as I mentioned earlier, it helps protect against muscle and bone loss. Plus, many people find Prolon easier to stick with simply because you get to eat something instead of facing five days with nothing but water. And based on clinical studies, Prolon has shown promise for improving inflammation, supporting metabolic health, and helping with conditions like Type 2 diabetes, autoimmune issues, and even cancer. (My daughter tried it recently while struggling with a persistent rash on her face. After completing the five days, she told me her skin hadn’t looked that good in months.)

What the Five Days Look Like

Day one starts with the most calories—about 1150—and then days two through five give you around 800. Each day includes two soups, a nut-based L-bar, and lots of really good herbal teas (hibiscus, spearmint, and spearmint lemon) (those three things are daily staples), but the other items—like olives, flax and seed crackers, and the small (but surprisingly good) chocolate crisp treat—rotate in and out depending on the day. There’s also a glycerol-based drink mix that you sip throughout the day (starting on Day 2), which is meant to support hydration and help prevent muscle and bone loss.

The Ease of Day One

Day one was a breeze. I barely noticed I was “fasting,” and the extra time freed up from not having to think about food or meals was oddly satisfying. That said, I did feel a little off throughout the week—not physically bad, just kind of unsettled. I realized how much of my day normally revolves around food: thinking about it, prepping it, shopping for it. That rhythm was gone, and I definitely noticed.

The Midweek Dip (a.k.a. Day Three)

The third day was probably my most difficult, if I had to choose one. I had one cup of regular coffee on days one and two, but decided to cut it out completely on day three. Technically, you’re allowed up to 140mg of caffeine per day on this plan, but I wasn’t sure how much was in my usual cup, so I skipped it just to be safe; I wanted to get the most benefits from autophagy as possible! I woke up with a slight headache on this day, so I ended up eating a third of the L-Bar that morning (I’d been saving it for dessert the first two nights) with some decaf my husband picked up—and within an hour, the headache was gone.

The Final Stretch: A Little Hungry but Hanging On

By days four and five, hunger was surprisingly tame—until evening rolled around. That’s when the craving for my normal rhythm crept in, along with a faint restlessness, like being in the last miles of a long road trip. I knew I had to see this self-imposed deprivation through for the best results, but the sixth day still felt distressingly far away. Of course, I stuck with it, and once I had eaten dinner, I was fine. However, my legs felt weak on days four and five. And after vacuuming the entire house on Thursday and mopping the floors on Friday, they felt even weaker and shaky. But my floors were pristine!

The Weight Shift: A Mini Roller Coaster

I weighed myself on Day 6 and saw I was down 2 pounds. The following week, I’d gained it back—but by the third week post-Prolon, I was back down again. They say you’ll likely regain about half of what you lose, and since I was already on the lower end of the scale, I figured I’d gain it all back. Honestly, I’m surprised I haven’t gained it back, especially with how much I’ve been eating lately.

But Here’s What Really Changed

That said, it’s not just the number on the scale—my body feels different in a good way. Looking back, it’s almost like there was a layer of static or low-grade tension buzzing through me before, and now it’s just. . .gone. I feel grounded and calmer—like my whole system hit a reset button.

Would I Do It Again?

Yes. Although, next time, I’d probably opt for the version with the premade soups. My friend—and quite a few people on the Prolon Facebook page—swear the premade soups are way better than the mix-it-yourself kind that I went with.

Is Prolon Right For You?

At this point, are you considering giving Prolon a try? It could be a great option for you if you want a structured on-ramp to intermittent fasting, or if you’ve already been doing IF but need a quick reset or a boost in seeing the results you’re after. It’s also a good choice for someone who wants the benefits of fasting but isn’t quite ready to go full-on with a water fast. If you’ve been curious about it, I say. . .maybe it’s time.

And as always: yes, you can fast your cake and eat it too. 🍰

P.S. Here’s a link to check out Prolon. I don’t get anything if you purchase it; I just think you should do it!