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Sugar Crash! How Low Blood Sugar Ruins Your Day

Updated: May 23, 2019

You may have heard of someone suffering from a sugar crash, and wondered what one is? Maybe you get them yourself?

I certainly know about them all too well because I used to get them several times a day when I was hooked on sugar!

In a nutshell a sugar crash is the result of eating a large amount of sugar or simple carbohydrates causing a blood sugar spike, which is then followed by a blood sugar slump.

A spike in blood sugar will give a temporary lift in energy, but that will soon be replaced by an overwhelming lethargy - or a sugar crash, which are the symptoms of low blood sugar.

As a former sugar addict, I was used to peaks and troughs throughout the day, sometimes feeling energised and then later feeling sluggish, but not really knowing what was the cause. Since quitting sugar, my energy levels are much more steady throughout the day, and sugar crashes are a thing of the past.

But in case you are suffering from occasional bouts of low blood sugar throughout your day along with the miserable feelings it can bring, I've written this blog to help you understand exactly what is happening, and how to prevent it.

woman asleep at her computer

How Our Bodies Get Their Energy

The technical term for low blood sugar is hypoglycaemia, and it can make you feel pretty horrible, as I will go into later. It happens when your blood sugar levels drop below 70 milligrams per deciliter, which is the lowest level to sustain the normal functioning of the body.

The energy source that keeps all living things going is glucose, and we get our supply of this energy source from carbohydrates, often in the form of bread, potatoes, rice, vegetables, fruit and milk. After eating, these carbs are turned into glucose which is distributed via your blood stream to every single cell in your body.

Your pancreas then creates a hormone called insulin, which takes the glucose out from your blood stream and into your cells to provide energy.

Whenever we eat sweet foods and treats, or drink sodas with sugar in them, our body takes a hit and our blood sugar rises dramatically.

No matter what type of sugar you eat, white or brown, honey, agave, maple, whatever, they all break down into roughly 50% glucose and 50% fructose when we digest them, creating unnatural spikes in our blood sugar.

Watch Out For The Simple Carbs

And it’s not just ‘sweet’ foods that will increase blood sugar levels, anything made with white processed grains such as white flour, will have the same effect. These 'simple carbohydrates' can create the same effect as eating a sweet treat because they very quickly turn to glucose and spike the levels in our blood.

sliced white bread

And unfortunately, if you spike your blood sugar, then insulin levels will overcompensate in an attempt to level out your blood, resulting this time in an unnaturally low blood sugar count.

So while eating anything that gives blood sugar levels a lift can also give you a temporary boost in energy, just remember that as soon as your insulin brings your sugar levels back down, and usually way below your normal range, then that’s when the ‘crash’ happens.

What does a blood sugar crash feel like?

A sugar crash can really make you quite unwell simply because your blood sugar levels are now too low. Remember, without enough glucose your body simply cannot operate correctly.

Every part of our body needs glucose as energy to function properly, from your muscles to your organs to your brain, and if they suddenly don’t get the energy they need then you just know you’re not going to feel good!

Symptoms of low blood sugar include:

  • Tiredness

  • Lethargy

  • Irritability

  • Headaches

  • Feeling shaky

  • Dizziness

  • Mood swings

  • Blurred vision

  • Difficulty concentrating

  • Hunger

So if you eat something with a high sugar, or high 'simple carb' content, soon enough you can expect to feel tired, lethargic and possibly irritable. You can get headaches, feel shaky, anxiety can kick in or you might have difficulty concentrating. And worse of all, low blood sugar levels will make you ‘feel’ hungry as your body becomes desperate to bring your blood sugar levels back up to normal again.

Woman yawning in a car

The current modern diet of excessive sugar intake and processed foods can often lead to a constant cycle of imbalance in our blood sugar levels.

And another problem we may suffer is the way we may have started to adapt to this cycle. If you are consuming excessive amounts of sugar several times a day over a prolonged period of time, (and for me that was literally decades!) your body starts to adapt to the sensations associated with our blood sugar being too low, and then only when the situation becomes critical do you really start to experience the symptoms.

Our blood sugar levels are on a literal rollercoaster every single day, bringing all of the nasty feelings with it!

What day to day activity can cause a sugar crash?

There are many reasons why you might end up with low blood sugar levels. Not eating for a prolonged period of time will result in low blood sugar for example.

Over exertion or excessive exercise can also reduce the glucose levels in your blood.

Eating a poor, unbalanced diet will also affect your blood sugar levels.

And eating a diet high in sugar will cause your blood sugar levels to fluctuate wildly.

Breakfast can be a particularly bad way to start the blood sugar rollercoaster. There are so many ‘breakfast’ foods that cause spikes. Orange juice, pastries, cereals full of sugar, allegedly ‘healthy’ breakfast bars, coffee’s loaded with cream and sugar… you get the picture.

croissants and orange juice breakfast

If you are starting your day off with these types of foods for your sugar fix then you might leave the house with a whoosh as you fly down the first rollercoaster hill and the sugar spike kicks in, but by eleven o’clock, you’ll be struggling to haul yourself up that next rollercoaster hump. So time for a muffin and a coffee? And whoosh, off we go again. Until lunch…

These cycles could be constantly happening to you, where you suffer from sugar crashes three or four times a day. A sugar crash can come in as little as fifteen minutes or take as long as two hours to arrive, but as sure as night follows day, if you spike your blood sugar, then a crash is sure to follow!

Illustration demonstrating the sugar addiction cycle

And you might even just be putting these sensations of lethargy and irritability down to tiredness - a lack of sleep or too much work, when its really just down to what you are eating.

Cutting out sugar and eating foods made from 'complex carbohydrates' such as wholegrains can keep your blood sugar nice and steady, meaning your energy levels will be on a much more even keel throughout the day.

So if you start the day with a solid, healthy breakfast, such as poached egg on wholegrain toast or a bowl of wholemeal porridge, the carbohydrates will be released slowly and evenly into your system, converting to glucose at a steady pace and keeping your blood sugar levels nice and steady.

Can low blood sugar levels ever become dangerous?

For a Type 1 Diabetic, hypoglycaemia can actually be life threatening. Anyone who suffers from this condition is unable to produce insulin at all and symptoms of severely low blood sugar levels include nausea, loss of sight, convulsions and even coma.

Man taking a blood sugar reading

How long does it take to recover from a sugar crash?

You can recover and get your blood sugar back up to within the normal range very quickly, literally within a few minutes, although the only way to do that is by eating or drinking something with a high sugar content. But by doing that, you can very easily create another spike, which will eventually lead to yet another crash.

What’s the best remedy for a sugar crash?

The easiest way to reverse the effects of low sugar levels is to eat something high in sugar or simple carbohydrate, in order to bring your blood sugar levels back up again. It doesn’t actually take much to bring levels back to normal, and just 15-20g of glucose can do the job.

Eating a piece of fruit like an apple or banana can provide a steady source of glucose, which is released slowly due to the fibre in the fruit.

Be aware though that the abnormally low blood sugar levels caused by your sugar crash may also cause a ‘false hunger’, where your body thinks it needs food. However it doesn’t necessarily need food, and it doesn’t mean you are undernourished, it is just trying to raise your blood sugar.

The danger here is that this type of hunger can lead to more overeating, causing another spike in the blood, starting the cycle all over again.

In fact, this type of hunger is often combined with cravings for sugar, due to the highly addictive nature of the fructose found in all types of sugar. Did you know that eating fructose actually makes you feel more hungry?

a bunch of bananas

So how do you prevent low blood sugar?

The simple solution to avoiding a sugar crash is to keep your blood sugar levels in a balanced state by avoiding eating foods high in sugar or eating 'simple carbs' like white bread or pastries.

Switch to wholegrain foods that contain the ‘whole of the grain’ including the husk, which takes longer to digest, providing the body with a slow, sustained release of carbohydrate, and therefore glucose, into the bloodstream.

Also, try to lower your sugar intake, and switch from sweet treats to savoury, as well as swapping sugary sodas for sparkling water. Just a single can of coke can put you over the recommended daily sugar limit!

I have written a blog here which outlines all of the other health benefits of cutting sugar out of your life 17 Amazing Things That Happen When You Stop Eating Sugar.

Tips to help prevent a sugar crash.

  • Start your day with a low sugar, balanced breakfast.

  • Try to not get hungry - eat healthy snacks between meals.

  • Eat a balanced diet, with complex carbohydrate, proteins and fats.

  • Learn to read food labels.

  • Anything with more than 5g of ‘Carbohydrate of which Sugars’ is high in sugar.

  • Anything with a sugar in the first 5 ingredients is high in sugar.

  • Eat smaller meals more often.

  • Try not to overeat at any meal.

  • Avoid simple carbs and switch to wholemeal bread, rice and pasta.

  • Cut down on sweets, chocolate, sodas and desserts.

Following just these simple tips can help you level your blood sugar throughout the day.

If you regularly suffer from sugar crashes or think you might have a sugar addiction, you can reset your metabolism and palate with a sugar detox.

If you would like help with this I have developed a program which is designed help busy people quit their sugar addiction in 21 days so that they can look and feel their best without giving up great tasting, healthy food.


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