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How to Prevent That Afternoon Blood Sugar Crash

author avatar Dr. Eric Berg 08/31/2023

Everyone has been there: you get to work, you have your lunch, and boom - blood sugar crash. You’re left in a slump and fighting to keep your eyes open so you can keep going with your day.

It’s a huge bummer, and it can majorly affect your productivity. Luckily, it’s not a given, and you can prevent that blood sugar crash with keto and intermittent fasting.

Let’s get into the details.

In this Article: -

  1. What Happens During A Blood Sugar Crash
  2. Causes of Blood Sugar Crashes
  3. The Solution: Higher Fat Diet
  4. Summary

What Happens During A Blood Sugar Crash

blood sugar crash reactive hypoglycemia sugar dependency

There is usually a process that happens during a blood sugar crash, or hypoglycemia.

First, you may experience a chocolate craving at around 11:30 in the morning. You eat it and spike your blood glucose levels. Then, at around 3:30-4:00 pm, you’ll start to crash. During this time, you’re going to feel symptoms like:

  • Tiredness
  • Irritability
  • Problems with your vision
  • Discomfort or anxiety
  • Headache
  • Lightheadedness
  • Shaking
  • Sleepiness
  • Hunger

Then, sometimes at night (usually around 8:00 pm) you’ll likely feel the need for something salty to crunch on.

These are the three most common points in time where you might have blood glucose symptoms and, ultimately, a blood sugar crash. In the big picture, this hypoglycemia can cause major problems for your productivity and your concentration.

You may start feeling these blood glucose crash symptoms when your blood glucose reading reaches 70mg/dL or lower. This is the threshold for hypoglycemia, or low blood sugar, according to the American Diabetes Association.

Overall, this rollercoaster happens most frequently if you're dealing with reactive hypoglycemia - or postprandial hypoglycemia - which is low blood sugar that occurs within four hours of eating a meal. This is different from diabetic hypoglycemia, and this difference is important to keep in mind.

Here’s the problem with reactive hypoglycemia - you can’t give in to these blood sugar symptoms or cravings, and most people do. When you give into these low blood sugar crashes, you actually make things worse (despite the fact that you may actually feel better at the moment).

Here’s what’s happening during this blood sugar roller coaster.


Cause of Blood Sugar Crashes: Sugar Dependency

sugar fuel from carbohydrates is inefficient energy

If you’re getting blood sugar crashes, it’s because your body is dependent on sugar fuel.

To get high enough blood glucose levels, you’re eating every hour and a half, and your blood sugar is probably going up and down like a rollercoaster each time you eat or have a snack. Now, you don't even need to be eating sugar for this to happen: you can get glucose from any source of carbohydrates, including fruit, vegetables, and grains. That means you may be dealing with sugar ups and downs even if you're eating healthy carbohydrates and "good-for-you" foods.

But isn't this unavoidable? After all, science shows that our brain and our body run on glucose and that - taking it back to high school biology class - it's the main way our body gets ATP or energy.

Well, this is true - usually, people do rely on glucose as their body's main source of fuel. The brain usually also relies on glucose, which is why people tend to get irritability and weakness during a blood sugar crash.

So why does this happen, and is it the only way?

First, the why. In order to deliver glucose to the muscles and cells in your body - as well as maintain proper blood sugar levels in the bloodstream - your body relies on a hormone called Fat Storing Hormone. This hormone is made by the pancreas.

Fat Storing Hormone issues are the hallmarks of diabetes. In type 2 diabetes, your body doesn’t have enough of this hormone to regulate blood sugar levels. You may also have Fat Storing Hormone resistance. In type 1 diabetes, the pancreas doesn’t make Fat Storing Hormone at all.

Still, Fat Storing Hormone problems aren’t exclusive to diabetes. When you have low blood sugar, you have too much Fat Storing Hormone circulating in the blood. Why? Because it also signifies that you’re triggering it every time you eat. Fat Storing Hormone is a regulating hormone that brings the blood sugar down. It's supposed to be triggered when you eat sugar in order to bring it down and normalize your blood glucose levels.

The problem, though, is that many people in the United States eat over 32 times the recommended amount of sugar every day - so their blood sugar is well above the normal range. They trigger Fat Storing Hormone too many times and they have far too much of it in their body. This is ultimately a trap that makes you feel worse over time health-wise.

With excess Fat Storing Hormone, you’ll ultimately experience things like:

  • Inflammation
  • Belly fat
  • Metabolic syndrome, etc

You can also develop Fat Storing Hormone resistance, which is when your cells stop accepting the hormone altogether because they simply don't know how to cope with the overload. This creates a dangerous cycle: your body continues producing more and more Fat Storing Hormone because your cells need it, but your cells keep blocking it and don’t release fat. As a result, you hold onto your blood sugar, you can’t lose weight, and you get huge amounts of inflammation.

Luckily, you don't have to rely on glucose as fuel for your body and brain. It is not the only way. Realizing that can help you avoid a lot of these problems.


The Solution: Higher Fat Diet

keto diet with intermittent fasting ketones more efficient fuel

To solve these issues, you have to increase the fat in your meals and encourage your body to run on fat, or ketones.

Why fat?

Well, fat is the least likely to spike Fat Storing Hormone of all the foods (much less than sugar and protein). You also want to make sure that you have a moderate amount of protein. If you don’t have enough protein, that can also affect the blood sugar levels.

Getting all this right is done through the keto diet with intermittent fasting. Now, just like with anything else, there are right ways and wrong ways to do the keto diet. A lot of people just eat cheese and chunks of butter all day and say, "Well, I'm on the keto diet, it's what I'm supposed to eat." And this doesn't work.

First, in my version of the keto diet for beginners, I highly recommend that you eat a lot of greens every day - particularly salad or cruciferous vegetables. The minerals in the greens will help stabilize blood sugar levels and avoid any negative symptoms that could otherwise come with doing keto. Apple cider vinegar can also be really important here. Overall, your nutrition breakdown should be:

  • 70% fat
  • 20% protein
  • 5% carbs
  • 5% vegetables

Second, I also always recommend that you combine keto with intermittent fasting. Here's the thing - any time you eat a large meal, even if you're eating mostly fat, you're going to have some kind of Fat Storing Hormone spike and instability in your blood. If you want to avoid this, you want to have very few large meals throughout the day. Hence the intermittent fasting.

Other solutions that you can add on?

Well, many doctors recommend that, if you want to deal with a blood sugar crash, you:

  • Eat smaller, more frequent meals: Snack throughout the day, or about every three hours.
  • Avoid high-sugar foods: These include processed carbohydrates, baked goods, white flour, and dried fruits.
  • Limit your alcohol intake: When you drink alcohol, be sure to have something to eat at the same time.
  • Avoid caffeine: If possible, switch to decaffeinated coffee or herbal teas.
  • Try to quit smoking: This should be done gradually under the guidance of a doctor.

That said, the single most effective solution is to get onto the keto diet with intermittent fasting. Ultimately, ketones (the byproducts of burning fat) can be considered a cleaner, more efficient form of fuel for the body and the brain. Running on ketones - instead of on glucose - can be very healthy overall.



Blood sugar problems happen often to people with type 1 and type 2 diabetes, but they can also happen to regular people that are dependent on glucose as fuel. If you continue to rely on sugar as your primary source of energy, you'll likely continue to have these low blood sugar symptoms.

My solution? The keto diet with intermittent fasting. This will decrease your dependency on sugar, help stabilize your hypoglycemia, and lead to a healthier, happier body overall.

Let me know if you have any questions.

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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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