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The 5 Reasons You Get Tired on Intermittent Fasting

author avatar Dr. Eric Berg 01/22/2018

exhausted woman slumped over her laptop

You were so excited to do intermittent fasting.

You’d heard about the benefits: weight loss, more mental clarity, and an abundance of energy. And it was that last one that really got you to commit to fasting. No more dragging through your days like someone had sucked the life out of you!

Only, it hasn’t been like that at all.

You’re still tired, even though you’ve been scrupulous about fasting every day. You’re about to give up. Some days you just want to gorge on thousands of calories in hopes that will boost your energy.

If intermittent fasting is supposed to give you more energy, why the heck do you feel so tired when you’re on it?

There are several reasons that are simple to remedy. Let’s take a look.

#1 You’re Going Too Quickly

If you’re new to intermittent fasting, and you’re trying to go right away to one or two meals per day, or go many more hours between meals than you’re used to, you’ll probably feel tired.

That’s because your body hasn’t yet adapted. Here’s what happens:

You don’t eat for hours. Your blood sugar levels drop.

Your brain, which still relies on sugar for its fuel, simply runs out of gas just like your car would halt if you ran out of fuel. When this occurs, you feel tired and cranky because of low blood sugar. You might get a headache. Your energy level crashes. You’re what’s known as “hangry”.

hangry young woman gorging on a burger and fries

The remedy: add a meal back in so you’re not going as long between meals. I strongly recommend that you follow a Healthy KetoTM diet when you fast. It’s a low-carb, high-fat way of eating that will make it easier for you to go longer between meals. One main reason why is because dietary fat keeps you feeling full longer than carbohydrates or protein.

So, back off a little, and go to three meals a day without snacking in between. Push your breakfast to later in the day until eventually it merges into and becomes your lunch. When you’re moving at a good pace for your body to adapt, your hunger will naturally lessen and you'll feel just fine between meals as you space them out longer.

#2 Your Adrenal Glands Need A Boost

If you’ve been fasting for awhile and are certain you’re not going too quickly, yet you still feel tired, here’s what may be happening.

You have adrenal fatigue.

If your adrenals - small organs that are located above your kidneys - are weak, your body can’t rebound your blood sugar to a normal level from a low level. Instead of being stable, your blood sugar keeps dropping.

One of the symptoms of adrenal fatigue is a sodium deficiency. The remedy then is simple: add more sea salt to your diet to help recharge your adrenals. This will help you become adapted to fasting, and give you more abundant energy.

As well, it’s possible you have a B vitamin deficiency, particularly of B1 and B5. B5 plays an important role in keeping your adrenal glands healthy. It’s a precursor to the stress hormones cortisol and adrenaline, which are produced by your adrenal glands. Because your hormones are meant to be in a delicate balance for you to be healthy, a deficiency can impact your health.

#3 Your Liver Is Damaged

Your liver stores sugar between meals. If you have a history of liver damage of some kind, whether it’s hepatitis or fatty liver disease, or you have a history of eating a lot of junk food and not eating enough vegetables, then you can be sure your liver needs extra support to help you adapt to fasting.

The remedy, besides eating a lot of raw vegetables in the salad, is to eat dandelion greens. They’re especially potent for cleansing your liver.

a bunch of dandelion greens

Dandelion greens are easily obtained at your local health food store. You may even have some in your yard that you can harvest and eat. Just make sure they haven’t been sprayed with pesticides.

Hate vegetables? I’ve got you covered with this smoothie recipe. (I’ll let you in on a secret: I’m not super fond of vegetables either! That’s why I created this smoothie recipe.)

#4 Your Stomach Isn’t Acidic Enough

You may be struggling to adapt to fasting because your stomach isn’t acidic enough to extract the nutrients you need from your food; thus, making it more likely you’ll be hungry.

Low stomach acid can also cause gastrointestinal infections and impair your digestion, so it’s definitely something you want to correct.

Some of the symptoms of low acid include:

  • Intestinal gas
  • Indigestion
  • Bloating when you eat
  • Heartburn

The remedy: drink apple cider vinegar mixed in water. If you feel better after consuming apple cider vinegar, you’ll know that you were deficient in stomach acid.

a dish of apple cider vinegar

Keep Going With Your Fasting, You’ll Feel More Energetic

You can see that the possible reasons you still feel tired are simple to correct. There are so many valuable benefits to be gained by staying with a fasting lifestyle, that I’d hate for you to abandon it.

I know how frustrating it is to still feel tired, especially when your expectations were so high.

Just follow the advice I’ve given here, and put yourself on a track to shed your fatigue and get an abundance of energy from fasting.

It will be worth it!

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Disclaimer: Our educational content is not meant or intended for medical advice or treatment.

Editor’s Note: This post has been updated for quality and relevancy.

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