Fasting Supplements Guide

Do you need supplements for fasting?

That depends mostly on the type and duration of your fast.

Intermittent Fasting, and short-term Extended Fasting (up to 48 hours) doesn’t usually require any special supplementation support. Although there are a few products that might make the process a bit easier. 

Extended Fasting of 2 days and more will definitely require electrolytes. 

Let’s look at each scenario in more detail.

Supplements for Intermittent Fasting / OMAD

There are many different protocols for Intermittent Fasting with varying length of fasting window. But they all typically include at least one refeed meal per day. 

Even with OMAD, your fasting window would be less than 24 hours. You have enough nutrients and electrolytes stored in your body tissues to last throughout this period. Any actual deficiencies are unlikely. 

There are a few exceptions. For example, if you do a heavy exercise session during your fasting window (or another sweat-inducing activity like sauna), your electrolytes may deplete enough for you to start feeling unwell, so you would need to replenish them.

If you already take generic well-being supplements like Multivitamins and Omega Oils on a regular basis, then by all means continue taking them throughout your IF. It’s best to take this type of supplement together with your refeed meal rather than during your fasting window. 

Supplements for Alternate Day Fasting 

Alternate Day Fasting (ADF) is a slightly extended version of IF with fasting window stretched to last a whole day, followed by refeed.

Just like with IF, it’s unlikely that you’d run into any vitamin deficiencies during this time.

However, because of the longer duration of the fasting window, electrolytes may become depleted. The rate of depletion is different for everyone and depends on factors like lifestyle, genetics and body composition.

Listen to your body and start taking electrolytes if you feel any symptoms of electrolyte deficiency. 

Supplements for Extended Fasting

If you plan to fast for more than 48 hours, you will definitely need to supplement it with electrolytes. 

Electrolytes are electrically charged minerals that are essential for the normal functioning of almost all of your body’s systems and organs. Normally we get a steady supply of them with food and drink.

During fasting, you are no longer getting your electrolytes from food. Your body has a small reserve of electrolytes stored in its tissues. But they deplete quickly, usually within the first 24-48 hours.

As soon as your body runs out of electrolytes, you will start feeling the symptoms of electrolyte deficiency. The most common ones are headaches, fatigue, irregular heartbeat, muscle cramps, nausea and just generally feeling unwell overall.

The only way to prevent these symptoms is to supplement electrolytes throughout your extended fast.

What are the key electrolytes to supplement?

Our bodies need the following electrolytes:

  • Sodium (Na)
  • Chloride (Cl)
  • Potassium (K)
  • Magnesium (Mg)
  • Calcium (Ca)
  • Phosphorus (P) 

The first three – sodium, chloride, potassium and magnesium – are the key ones to replenish during fasting.

Standard table salt (including variations like Himalayan pink salt) ticks two of these boxes as it consists primarily of sodium chloride. 

Phosphorus and calcium play less of a role during your fast but become more important during the refeed phase.

The ratios of these electrolytes are also important.  Most recommendations fall within the following ranges:

Sodium: 5000-7000mg

Potassium: 1000-3500mg

Magnesium: 300-500mg

How much electrolytes do I need during Extended Fasting?

There is no one-size-fits-all answer.

The concept of government-approved “recommended daily values” contributed to a myth that our nutritional needs are uniform. We can use these figures as a very approximate starting point. But our individual requirements for electrolytes can vary significantly based on multiple factors. In fact, they fluctuate day-by-day even for the same individual. 

Here are some key factors to consider.

Duration of the fast 

Your electrolyte needs will increase gradually. If you are only fasting for 2-3 days, you won’t need as much as someone who plans to go for 7-10 days.  

Body build and composition

If you are big and/or tall, you may need more electrolytes than someone with a smaller body. Body composition matters as well because muscle tissue, fat and bones utilise electrolytes in different ways.


If you exercise a lot, you will need more electrolytes than someone who doesn’t. We lose electrolytes with sweat so high-intensity exercise depletes your electrolyte levels quickly. Muscle recovery after anaerobic exercise also uses them up.

Medical conditions and medications

Certain medications and medical conditions (especially those related to kidneys, cardiovascular health and digestive system) may affect the level of electrolytes in your body. Supplementation may also interact with the medication in unpredictable ways.

It goes without saying that if you are on any medication or have any kind of medical condition, you should discuss fasting and electrolyte supplementation with your doctor before attempting it.


If you normally eat plenty of foods that are rich in electrolytes, you will have more of them stored in your body tissues and may require less supplementation, especially in the beginning.

Weather and climate

Sweating depletes electrolytes quickly, so you may need more electrolytes if you live in a hot climate, or during periods of hot weather.

Drinking water

The quality of drinking water varies widely by region. Some areas are lucky to have tap water that’s rich in electrolytes and others have hardly any. Likewise, if you usually drink bottled mineral water instead of tap water, that will provide more electrolytes.

Read more about Fasting Electrolytes 

How to find your personal optimal level of electrolytes

The best way to find your own optimal dosage is to start small and gradually build up. 

Listen to your body and adjust the dosages depending on how you feel. 

If the dosage is too low, you can always take more later. But if it’s too high, getting it out of your body may be unpleasant (vomiting, diarrhoea).

Do I need to take a multivitamin during my fast?

Most people don’t need to take multivitamins during fasting.

Vitamins A, D, E, and K are fat-soluble. They are stored in fat tissues. As we lose the fat with fasting, those vitamins are released and the body can access them. 

Water-soluble vitamins B and C are also stored in our body tissues. One interesting point to note about them is that the body uses these vitamins to assist the digestive system and nutrient metabolism. These processes work very differently during fasting so you use up a lot less of this type of vitamins.

There are some exceptions. If you have a pre-existing vitamin deficiency or if you get any symptoms of it during your fast (for example, hair loss), then you may need to get a multivitamin.

Supplements for your Refeed Phase after a long EF

If your extended fast was 14 days or longer, you may want to consider some additional supplements to assist your refeed phase.  

Take the following at least 30 minutes before breaking your fast: 

  • Phosphorus
  • B vitamin complex 

Continue taking your electrolytes in smaller dosages for several days after the end of your fast. 

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