The ProLon® L-Drink Mystery: Why I Had to Make My Own (And What I Learned)
So there I was, three weeks post-FMD experiment, still riding the wave of actually sustainable energy levels, when my friend Maya texts me: "Hey, saw your fasting post - what's the deal with that L-Drink thing? Is it just expensive flavored water?"
Valid question, Maya. Honestly, when I first encountered the ProLon® L-Drink during my research rabbit hole phase, I had the exact same reaction. Here's this fruit-flavored beverage that somehow fits into a fasting protocol - which seems about as logical as "healthy" donuts or "low-carb" pasta.
But here's the thing about me and mysterious ingredients: I can't let them go. So naturally, I spent my weekend diving headfirst into glycerol research papers instead of doing literally anything else productive.
What I Discovered About the L-Drink (And Why It's Not Just Marketing)
Plot twist: the L-Drink actually serves a really clever biological function. The main ingredient is vegetable glycerine (glycerol), which provides your body with an external energy source that doesn't technically break your fast. Think of it as a metabolic cheat code.
During fasting, your body starts breaking down muscle protein to create amino acids for glucose production - a process called gluconeogenesis. Not ideal when you're trying to preserve muscle mass. The glycerol in the L-Drink basically steps in and says "hey, use me instead of cannibalizing those muscles."
The research on this is actually pretty solid. Studies show that glycerol from fat stores normally contributes significantly to glucose synthesis during fasting. The L-Drink just provides this externally, taking pressure off your muscle tissue.
My DIY Investigation (Because Of Course I Had To)
After reading about glycerol's role in muscle preservation during my day-5 disaster, I knew I wanted to incorporate this into future fasting attempts. But buying the official ProLon® L-Drink for regular use? Let's just say my budget had opinions about that.
So I created my own version. Here's what actually works:
The Basic Formula:
- 5 mL (1 teaspoon) food-grade vegetable glycerine
- 1.2 litres (40 ounces) purified water
- Fresh lemon juice (optional, for taste)
- Pinch of sea salt (because electrolytes matter)
The trick is mixing it thoroughly - glycerine is denser than water and will sink to the bottom if you don't shake it properly. I learned this the hard way when I got a mouth full of sweet, syrupy surprise at the end of my bottle.
The Body Weight Math That Actually Matters
Here's where it gets interesting for data nerds like me. The optimal glycerol dose is typically 0.1 to 0.3 grams per kilogram of body weight. So for my 63 kg frame:
63 kg × 0.2 g/kg = 12.6 grams of glycerol per day
Since there are about 6.3 grams of glycerol in 5 mL (1 teaspoon), I land at roughly 10 mL (2 teaspoons) daily, which I spread throughout the day rather than chugging all at once.
For those who prefer to skip the math: start with 5 mL (1 teaspoon) in 1.2 litres (40 ounces) of water and see how your body responds. You can always adjust up if needed.
What I Noticed During My Second FMD Round
Armed with my DIY L-Drink starting on day 3 (not day 1 - timing matters), my second FMD experience was dramatically different. That brutal day-5 headache? Completely avoided. The muscle weakness I felt last time? Minimal.
But here's what really surprised me: the mental clarity was even sharper. I expected the physical benefits, but the cognitive effects were unexpected. I felt like my brain was running on premium fuel instead of whatever fumes I was operating on during round one.
The energy difference was night and day. Instead of feeling depleted by day 4, I felt... steady. Not energetic exactly, but not like I was running on empty either.
Quality Control: What to Look For
When sourcing vegetable glycerine, don't grab the first bottle you see. You want food-grade quality with USP (United States Pharmacopeia) certification. Industrial-grade glycerine contains impurities that you definitely don't want in your body.
I found mine at a local health food store, but it's also available online. One bottle lasts for multiple fasting cycles, making the per-use cost pretty reasonable.
The Real Talk About DIY vs. Commercial
Let's be honest about the differences. My homemade version captures the essential metabolic function, but it's not identical to the ProLon® formulation. The commercial version has proprietary natural flavors, specific preservatives, and has been clinically tested in research settings.
Why I still prefer DIY:
- Cost (significantly less expensive for regular use)
- Control over ingredients
- No artificial preservatives
- Fresh preparation each time
When commercial might make sense:
- Following the complete research protocol exactly
- Convenience factor
- Consistent flavor profile matters to you
For my purposes - supporting general fasting periods and understanding how my body responds - the DIY approach gives me what I need while satisfying my need to understand exactly what I'm consuming.
Timing Strategy That Actually Works
Based on my experiments and research deep-dives, here's what I learned about optimal timing:
Start the L-Drink on day 2 or 3 of your fast, not day 1. Your body needs time to shift into fasting mode before the glycerol support becomes beneficial. Sip it throughout the day rather than drinking it quickly - this maintains steady glycerol levels and better supports hydration.
I typically divide my daily amount into three portions: morning, midday, and evening. This seems to provide the most consistent energy support without overwhelming my system.
The Digestive Reality Check
Some people experience mild digestive effects from glycerine, especially when starting. I had zero issues, but Maya (who tried my recipe) needed to dilute hers initially. Start with a slightly weaker concentration and gradually increase as your body adapts.
Also worth noting: glycerine is sweet, which feels weird during fasting. Your brain might interpret this as "breaking the fast" even though metabolically you're not. It took a few uses to get comfortable with this mental disconnect.
Where This Fits in the Bigger Picture
The L-Drink works best as part of a comprehensive fasting strategy, not as a standalone magic bullet. Dr. Longo's research shows that the complete FMD protocol creates synergistic effects - the specific calorie restrictions, macronutrient ratios, and yes, the L-Drink all work together.
If you're incorporating a DIY version into your routine, understand that it supports the fasting process but doesn't replace proper preparation, gradual adaptation, or (when appropriate) medical consultation.
What I Wish Someone Had Told Me
The L-Drink isn't about making fasting "easier" in the way that a cheat meal makes dieting easier. It's about making fasting more metabolically efficient while preserving muscle mass. Understanding this distinction helped me set appropriate expectations.
Also, the glycerol doesn't eliminate fasting discomfort entirely. You'll still experience the mental and physical shifts that come with extended calorie restriction. What it does is provide metabolic support that helps your body handle the stress more effectively.
The Bottom Line
Creating my own L-Drink taught me that understanding the "why" behind nutritional interventions matters more than blindly following protocols. Glycerol's role in gluconeogenesis and muscle preservation during fasting is well-established science, not wellness industry marketing.
Whether you choose the commercial ProLon® L-Drink or experiment with DIY versions, the goal remains the same: supporting your body through fasting while maximizing benefits and minimizing unnecessary stress.
For me, the DIY approach hits the sweet spot of scientific understanding, cost-effectiveness, and personal experimentation. Plus, there's something satisfying about creating a solution that works for your specific needs rather than accepting a one-size-fits-all approach.
The beauty of understanding the science means you can make informed decisions about what works for your situation, budget, and goals. And honestly? That level of understanding and control feels more valuable than any commercial formulation.
Have you experimented with glycerol supplementation during fasting? I'm curious about others' experiences with both commercial and DIY approaches. Drop a comment and let me know what worked (or didn't work) for you.
Quick disclaimer because science and safety matter: This is my personal experimentation journey, not medical advice. Always consult healthcare providers before starting extended fasting protocols or supplements, especially if you have underlying health conditions. ProLon® is their trademark, not mine.