What happens when you eliminate carbs from your diet?

What happens when you you eliminate carbs from your diet?

Well, a number of interesting things will happen to your body.

I’ll elaborate more on all of these, but this is what you can likely expect:

  • Your body will start burning ketones for energy, entering into a state of ketosis
  • You may experience symptoms of carb flu
  • You may lose a considerable amount of weight
  • You may really enjoy the experience, or absolutely hate it…there doesn’t seem to be much middle ground here

Quick warning:

Alright, in all honesty this answer has the potential to be very science heavy. I’ll do my best to simplify everything as much as possible, without diluting the science toomuch.

So, ready to learn what will happen if you don’t eat carbs for 3 weeks?


Lets get started slashing those carbs.

First of all, what is a carb?

Before we start talking about what’s going to happen when you stop eating carbs, it seems like a good idea to first define what a carb is.

When you think about carbs, what jumps to mind?

English muffins?

Yea, that’s what jumps to my mind too.

However, those are technically foods, which simply contain carbs.

“Carb” is short for carbohydrate.

In science speak, carbohydrates are classified by their chemical structure. Typically, we refer to them based on their complexity.

The three types of carbs are:

  • Monosaccharides
  • Oligosaccharides
  • Polysaccharides

Why are carbs important?

Carbs are the body’s preferred fuel source. They provide immediate energy to the cells, and cause the release of insulin.

In more simple terms: Carbs are the easiest energy source for the body to break down, and convert into usable energy.

They also taste amazing.

More importantly though, carbs provide your brain with energy in the form of glucose (sugar).

The brain requires about 120–130g of glucose per day. When you’re eating enough carbs, the brain easily gets enough energy.

But what happens when you eliminate all those carbs?

What happens when you eliminate carbs from your diet?

As you just learned, the brain/body prefer to use carbs for energy. Namely, because they are easy to breakdown and provide an immediate supply of energy in the form of glucose.

However, even if you eliminate carbs your body/brain still needs to get energy.

And, that energy has to come from somewhere.

Enter, The Ketone Body.

When you eliminate all carbs from your diet your liver will start to make ketone bodies to be used for energy; specifically to fuel your brain, heart, lungs, organs, and muscle (pretty much in that order, too).


Because the human body is smart, and will do anything to create energy for the brain.

The physiological process of ketosis isn’t that complicated to understand, but it’s definitely heavy on the science. I’ll spare you a boring diatribe about human physiology, and metabolic pathways, but know that it involves words such as:

  • krebs cycle
  • acetyl-CoA
  • beta oxidation
  • oxaloacetate molecules
  • fatty acid metabolism and mobilization

But, if you’re like me and like to geek out over science, AND you want to learn more about the physiology behind ketosis, check out the article below. I promise you it’s super science heavy…

Multi-dimensional roles of ketone bodies in fuel metabolism, signaling, and therapeutics

Ok, to quickly recap:

When you eliminate all carbs your liver produces ketone bodies, which in turn get converted to usable energy that supply the brain first. Essentially, this whole process is known as “ketosis”.

Ketosis isn’t the body’s preferred way to get energy, but it will keep you alive in times of starvation (or fasting), or when you just decide to eliminate all carbs because you can do that now-a-days.

The dreaded carb flu

Symptoms of carb flu generally appear right at the beginning of ketosis. How long these symptoms last is highly subjective, and depends on the person.

However, average lifespan of carb flu is in the neighborhood of 4–7 days.

When you get carb flu, you’ll know. Trust me. These are some of the unmistakeable symptoms associated with it:

  • dizziness
  • overly fatigued
  • muscle cramps
  • difficulty sleeping
  • experience brain fog
  • metallic tasting mouth
  • become quite irritable…if you’re not already ←haha, that was a joke

What can you do about carb flu?

You can eat more fats.

If you’ve been eating carbs, then stop, you’ve likely removed a lot of calories from your diet. You may be experiencing symptoms of carb flu because you’re simply just not getting enough calories.

The solution: eat a lot more fat and see if that helps.

You can eat more salt and dink more water/electrolytes.

When you eliminate carbs, you eliminate a lot of glycogen in the body. Glycogen binds to water. Thus, by eliminating carbs you actually eliminate a lot of water from your body.

To retain that water you can add salt to your foods, drink a lot more water, or even drink a carb free beverage containing electrolytes. That should help fight any dehydration which may be settling in.

What about weight loss?

Well, weight loss is all about creating an energy deficit in your body.

And, if you cut all carbs chances are high you’ve eliminated enough calories from your diet to create a substantial calorie deficit. This is good for weight loss.

It’s not uncommon to hear of people going on a keto diet and quickly losing 5–10 pounds in the first two weeks. This actually happens surprisingly often on this type of diet.

And, brace yourself.

I’m about to show you a picture of me after my last two week keto diet challenge.


Will you enjoy eliminating carbs?

Hard to tell.

Some people really love a low carb/keto style diet, and do quite well on it.

Other people absolutely hate a low carb/keto style diet, and don’t do well on it.

The only way to know for sure is to try it for yourself and find out.

Personally, I really liked it, and will be doing a 2 week keto challenge about twice a year now.

Can you eliminate carbs forever?

I don’t recommend eliminating ALL carbs, for a long period of time.

Your body can stay in ketosis for a long time. This is a highly evolved survival mechanism, developed over quite a while.

However, the body does best when there are some carbs coming in.

You can stay on a low carb diet for a longggg time, but I don’t recommend trying to eliminate ALL carbs forever.

Final thoughts

If you eliminate all carbs from your diet chances are high you’re going to lose some weight, probably experience some symptoms of carb flu, and you’ll know rather quickly whether you hate it, or love it.

It’s definitely worth trying out, though.

I hope this answer can help you on your keto journey.

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