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ProLon L-Drink Glycerine Content – DIY Version

This post has been put together to approximate how much glycerine is used in the ProLon L-Drink in case you want to replicate it yourself.

Note: this is not medical advice, and you should consult with your healthcare physician before embarking on an intervention like fasting.

Glycerine Dosage Calculator

Your weight:

Once you have calculated how much vegetable glycerine you would need per day, you would then:

  • Measure this out each day on days 2, 3, 4 & 5.
  • Add it to a water flask, and shake to mix. If it’s not mixing due to the water being cold, using warmer water may help with the initial mix.
  • Optionally add a calorie-free flavoring. The L-Drink does this to improve palatability.

How is this estimate derived?

As you may be aware, each ProLon box contains 120ml (4 fl oz) bottles called the L-Drink for days 2, 3, 4 and 5.

You can see in the below image the notches that are used on the side of the bottle to measure out the glycerine.

The basis for the calculatoins is the nutritional data of the L-Drink, which indicates that 100 ml contains 118 calories.

I assume that these calories are derived solely from glycerine, excluding any caloric contribution from other ingredients like natural flavour and Potassium sorbate. This assumption, while not exact, serves as a reasonable approximation for our calculations.

I then consider that:

  • Glycerine has a caloric density of 4.32 calories per gram
  • A physical density of about 1.26 g/ml
  • From this, I deduce that approximately 21.68 ml of glycerine is present in every 100 ml of the L-Drink.
  • This understanding allows us to correlate specific volumes of the drink with body weight categories: 20 ml for 30 kg, increasing linearly up to 100 ml for 100 kg, and capping at 120 ml (the entire bottle) for weights of 120 kg and above.

What’s the purpose of the L-Drink?

Valter describes the function of the L-Drink as being to provide an external source of glycerol.

People who are in a fasted state naturally produce glycerol, and this is used for gluconeogenesis (the production of glucose (energy) from non-carbohydrate substrates like fat and muscle).

Valter notes in the video below that after 3 ProLon cycles, when measured, people are found to have lost minimal amounts of muscle – and one of the reasons could be due to the L-Drink.

L-Drink Ingredients & Functions

L-Drink Nutrition – source
  • Purified water: Unlikely to form any function, other than as a base to mix the rest of the ingredients into, and then bulk them up for measuring out quantities.
  • Vegetable glycerine: As mentioned above, this provides the body with an external source of glycerol to aid in gluconeogenesis.
  • Natural flavor: To make it more interesting to drink.
  • Potassium sorbate: Likely a preservative.

Is Vegetable Glycerine Safe?

Vegetable glycerine is commonly used in food & cosmetics. For example in food, it’s used to prevent cake icing from setting too firm, and for making ice cream softer to scoop.

In a 2012 study into the effectiveness of glycerol for sports performance, they used a dose of 1.2 grams per kilogram of bodyweight for each study participant, with no noted adverse health effects1The Effect of Glycerol Supplements on Aerobic and Anaerobic Performance of Athletes and Sedentary Subjects – J Hum Kinet | 2012.

1.2g/kg is a much higher dose than is used in ProLon.

For clarity – glycerine and glycerol are the same thing, however commercially it’s often referred to as glycerine, and inside the body as glycerol.

Where can I buy vegetable glycerine?

Many will be familiar with seeing glycerine available in supermarkets, typically in the baking aisle. It can also be found on Amazon and other online retailers. You can check if it is “food grade” just to be on the safe side.


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1 year ago

I really appreciate your effort. Maths are not my strong suit. Thank you so much!

1 year ago

Thanks. I’m on my 2nd round of the Prolon fast. I had great success with the first round. I’ve adopted it for general health, not just for weight loss. However, I dropped a few pounds and have kept them off. I was most surprised to see that my athletic strength didn’t suffer at all. I was expecting to lose muscle mass. In fact, by Day 4 of the fast, I was cycling as strong as I had been the week earlier: 20 miles and 2,000 feet of elevation, in spite of the low calorie diet. The glycerine might have played a big role. I was probably burning fat more than I do normally. Thanks for the explanation.

John Brown
John Brown
Reply to  Joe
4 months ago

Thanks for this! Just starting my first DIY week.