How Much Salt Do You Need While Fasting? [& How to Get It]

How much salt do you need while fasting

I’ve tried fasting with and without salt.  When I fast with salt, it’s a lot easier.

Basically, having enough salt during a fast (especially a long fast) helps me feel more energetic, and able to do physical activities that might otherwise be difficult.

It also helps prevent certain side effects, like headaches or fatigue.

Overall, salt is one of the main keys to feeling well during a fast. Especially an extended fast.

In this article, I’ll explain why salt is helpful, and how much salt it makes sense to use under various circumstances–including short fasts, long fasts, or a low carb diet.

Let’s dive in.

Is Salt Bad for You?

First, the elephant in the room.

Many people have been told they should limit their salt intake. So when they hear the opposite–that they may be better off consuming more salt–obviously they may be confused.

Without getting into all the details, the short answer is:

Salt is not nearly as bad for us as we’ve been led to believe. And in some cases, you may be doing more harm than good by trying to limit your salt intake.

For example, a recent review article showed that restricting salt often leads to problems with blood sugar and insulin resistance. Which is ironic, because people who are advised to limit salt are often people who already have problems with blood sugar and insulin resistance.

If you want to dive deeper and understand why restricting salt may do more harm than good, check out the book called The Salt Fix.

The Salt Fix book

How Much Sodium / Salt Do You Consume on a Normal Day?

Chances are, you don’t know how much sodium you’re eating on a typical day.

But when people are told to limit their sodium, that usually means keeping the amount of sodium that they eat under 2 grams (2,000 milligrams) per day.

Quick side note: Salt and sodium are basically the same thing, because table salt is sodium chloride.

If you’re not trying to limit your salt / sodium intake, you probably eat well over 2 grams per day, maybe even as high as 5 or 10 grams (5,000 or 10,000 milligrams).

That should give you a little context about typical sodium intake (whether you’re trying to limit your sodium, or not).

How Much Sodium / Salt Should You Consume on a Low Carb or Ketogenic Diet?

When people start a low carb diet, they’re typically advised to consume more salt than they otherwise would. 

There are a couple reasons for this:

First, when you eat a low carb diet, that typically means you’re not eating as much junk food. And processed junk food typically has a lot more sodium added to it. So chances are, you won’t be eating as much sodium anyway on a low carb or ketogenic diet.

Second, when you switch to low carb, your insulin level gets lower. And when your insulin level gets lower, your kidneys excrete more sodium.

Extra salt helps on a ketogenic diet

In other words, you pee out more salt.

For both of the reasons listed above, you’ll end up having less sodium in your body when you’re on a low carb diet. As a result, it makes sense to consume more.

The bottom line?

People eating a low carb or ketogenic diet are usually advised to eat about 4-7 grams of sodium per day. In other words, 4,000 to 7,000 milligrams.

That may sound like a lot, but it’s actually not that much when you put it in context. And getting adequate sodium has a lot of benefits.

How Much Salt Do You Need During Intermittent Fasting?

When people say intermittent fasting, usually they mean time-restricted eating. In other words, eating all your food for the day in a limited window of time.

For example, you can have a 10-hour eating window, and fast for 14-hours overnight.

Under these circumstances, you may or may not need to go out of your way to consume more salt. It depends on: 

A. Are you also eating a low-carb diet? (see above) 

B. How long are you fasting each day?

If you’re fasting for a really long time (like 23 hours each day), then naturally it becomes more helpful to consume extra salt. If you’re only fasting for a couple extra hours per day (e.g. a 14-hour eating window), then you probably don’t need to change that much.

How Much Salt Do You Need During Extended Water Fasting?

When you’re on a long fast, naturally you’re not consuming any salt with your food.

You’re also losing more salt / sodium in your urine, because your insulin is quite low.

The end result?

Overall, your sodium level will be quite a bit lower during a long fast than it is on a typical day. 

As a result, you may feel lower energy, or have other side effects. For example, it may be more difficult to exercise.

Sodium is the main electrolyte that helps maintain your blood pressure. So when your blood pressure gets lower than what you’re accustomed to, that can lead to side effects listed above, as well as fatigue or other symptoms.

How Much Salt Should You Use During Prolonged Water Fasting?

Basically, the answer is similar to what I explained above – about sodium consumption on a ketogenic diet.

People on keto are advised to consume about 4-7 grams of sodium per day. So if you’re on a prolonged water fast, you may also want to consume about 4-7 grams of sodium each day.

Naturally, that’s a ballpark figure, and it will vary from person to person. But it gives you a general idea at least.

There are various ways to get this extra sodium into your body, which I’ll explain further down.

What about People with Congestive Heart Failure (CHF)?

While I’m not giving individual medical advice in this blog post, or anywhere else, here are a few things to consider:

On a normal day, somebody with CHF might be advised to limit their sodium intake to about 2 grams. So if that same person is fasting, wouldn’t it be reasonable to also consume about 2 grams of sodium in a day?

Probably so.

But as I said, this isn’t individual medical advice, so talk to your own medical providers.

What about Kidney Failure?

People who have kidney failure or are on dialysis do need to be careful about their electrolyte intake. And kidney failure is complicated, so definitely consult with your nephrologist (kidney specialist). 

But just as a general idea, it may also make sense to consume about the same amount of sodium as you would on a normal day, when you’re fasting. 

Otherwise, you’ll be going from whatever you normally consume, all the way down to 0 grams of sodium per day. And therefore you might have some of the same symptoms such as fatigue, headaches, or not feeling able to exercise on the days when you’re fasting.

How Can You Supplement Salt / Sodium while Fasting?

I’ve talked about this elsewhere, so I won’t go into a lot of detail here. But supplementing your salt is pretty easy.

The most obvious way is to just put some salt on your tongue, and then wash it down with water. But there are more palatable ways as well, and that’s what I usually do.

For example, you could use:

  • Bouillon cubes
  • Veggie broth
  • Soy sauce
  • Dill pickles
various salt sources to use while fasting

What do all those things have in common? 

They’re all very high in sodium, and very low in calories.

In other words, you’re not putting very much energy into your body, but you are putting a lot of sodium in, which can help you get up to those 3 or 4 or 5 grams of sodium that you’re trying to get into your body on a fasting day.

What about Electrolyte Packets?

If you prefer, you can also try a premixed electrolyte packet. 

Just be careful about sweeteners or added sugar.  Because anytime you consume something sweet while fasting, it may throw you off your game.

Here’s one example of an electrolyte packet that doesn’t have any added sugar or sweeteners.  Feel free to try it, if you would like.

Conclusion: How Much Salt / Sodium do You need While Fasting?

Consuming extra sodium (aka salt) while you fast is generally quite helpful.

It helps prevent various side effects, typically will boost your energy level, and makes it easier to exercise while you’re fasting.

Since you’re not consuming any salt with your food on fasting days, and you’re also losing more sodium in your urine, for most people it does make sense to consume more salt on a fasting day than they otherwise would.

Generally the amount of sodium you’d want to consume during extended water fasting is somewhere between 4 grams and 7 grams (4,000 milligrams and 7,000 milligrams) of sodium per day.

Naturally this may vary depending on your medical situation, so always consider your individual circumstances and talk to your doctor or other medical providers as needed. 

For more information about how to get started with intermittent fasting, check out my complete beginner’s guide to intermittent fasting.

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Hope it helps!

Picture of Ben Tanner, PA-C

Ben Tanner, PA-C

Ben has been practicing as a physician assistant (PA, or PA-C, similar to a doctor) in emergency medicine, urgent care, and family practice since 2014. Since 2016, he has developed an avid interest in various forms of fasting, using it to improve his own health while helping friends, family, and patients do the same.