Magnesium and Sodium

While fasting, do you feel low energy? Do you feel irritable? Do you have trouble sleeping or find yourself waking up at irregular time?

If you experience any of the above, you might be suffering from an electrolyte deficiency. Magnesium and Sodium are incredibly important electrolytes one needs while fasting and they will make your entire fasting experience much more pleasant.

Why Supplement?

Let’s start with the why. Here is a great basic explanation of what electrolyte depletion is while fasting:

You may know that electrolytes have something to do with the way water behaves in your body, but what exactly is an electrolyte? Simply put, it’s a mineral that, when dissolved in a solution, is electrically charged—electrolytes are “electric.” They’re critical for a bunch of essential functions. Yes, they help maintain fluid balance, but they also aid in muscle contractions, keep your heart beating normally, and help your body send signals from your nervous system to cells throughout your body.

Since you aren’t eating during a fast, you aren’t getting electrolytes through food. Even if you’re time-restricted-feeding (doing a 16:8 for example), there are 16 hours of the day when you aren’t getting a consistent stream of electrolytes into your body. Even non-fasters are at risk for electrolyte deficiency. Supplementation may be critical to help keep your body functioning properly, especially on a longer fast. 

Supplementing with two key electrolytes—magnesium and sodium—may also help you avoid some of the nasty side-effects of electrolyte depletion. 


I’m also not the only person who supplements during a water only fast. Peter Attia, one of the leading experts in how to live longer, be healthier, and optimize your performance, who also regularly fasts supplements as well:

[During a water only fast] I’m supplementing with sodium and magnesium being the two main things.

Peter Attia (52:57)

And lastly an important medical disclaimer before getting in to what I supplement with:

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For magnesium, you’ll likely want to supplement just above 100% of the Recommended Dietary Allowance. You’ll also want several different molecular forms including one or two types of slow-release mag to maintain a steady drip of magnesium in your bloodstream, and to avoid any GI distress. 


Supplement 1: L-threonate

tl;dr: I take 2 pills before bed

I ordered this brand of this brand of Magnesium L-threonate on Amazon. Per Zero it is: a novel and proprietary form of magnesium developed by scientists at MIT. It’s better absorbed than magnesium oxide and has been used to support brain health and sleep. In this form, magnesium is bound to L-threonate, a magnesium transporter that helps it cross the blood/brain barrier. Magnesium L-threonate has been shown to have a calming effect, which is why people often take it in the evening.

[I take] two Magnesium L-threonate before bedIt’s really a fantastic product… I’m glad I passed ten different times on investing in the company.

Peter Attia on the Tim Ferriss Show (52:50)

Supplement 2: SlowMag

tl;dr: I take 2 pills in the morning and 2 pills before bed

I ordered this brand of Slow Release Magnesium on Amazon as per Zero: your magnesium intake should include at least one or two slow-release forms to optimize a steady uptake throughout the day.

I take two SlowMag in the morning, two slow mag before bed.

Peter Attia on the Tim Ferriss Show (52:50)


tl;dr: I have 2-3g of sodium per fasting day if I’m not exercising, and 3-4g of sodium if I am (1g of this coming within the hour before exercise)

For sodium, you’ll want 2-3g per fasting day if you’re not exercising, and 3-4g if you are. 4g is about 4 servings (or two whole cubes) of bouillon, depending on the brand, or 2.5 tsp of pink himalayan Sea salt. If you’re exercising, have a mug of bouillon or chew on a few salt crystals in the hour before your workout. 


To make sure I get enough sodium I drink two things:

  1. ACV Drink: Three tablespoons of Apple Cider Vinegar + 1 teaspoon pink Himalayan sea salt + 24 ounces of water = 2.3g of sodium
  2. Bouillon Drink: 1 cup Hot Water + 1 teaspoon of Knorr Bouillon Caldo Con Sabor De Pollo Chicken Flavor Bouillon = .87g of sodium

In total, this is 3.17 g of sodium that I know I will be getting daily. In addition to this, I salt my food to taste but this ensures I get enough sodium per day.

Lastly, is there an optimal time to consume sodium? If you exercise during a fast, yes!

If you exercise during your fast, you may need even more sodium to compensate for what you lose to sweat. Volek and Phinney recommend that you consume one additional gram of sodium within the hour before exercise to account for any extra losses. So, to keep our math up to date: if you’re exercising during a fast, that would mean 3-4 grams of sodium per day, with a gram of that being consumed before you work out. 


So in summary, my sodium supplementation is as follows:

  • Within the hour before my workout, I have half of my ACV drink = 1.15 g of sodium
  • After my workout, I have the other half of my ACV drink = 1.15 g of sodium
  • During dinner I have one Boullion drink = .87g of sodium
  • Over the course of the day I might sprinkle a pinch of salt in my water as well

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