The Science of the Sugar Crash Back to Blog >

The Science of the Sugar Crash

October 20, 2021

We all crave something sweet every now and then, but has satisfying your sweet tooth lately led to feelings of fatigue? Don’t worry, you’re not alone! There is a proven scientific correlation between sugar and carb consumption and energy levels dropping soon after. With all of the sugar we eat in the US, some people struggle with this problem all the time. In fact, the average American eats as much as three pounds of sugar every week (1)! And that’s not just from the sugary treats – many packaged foods that may not taste sweet can still contain added sugars to enhance flavor. The fact is, you are probably eating a lot more sugar than you even realize – and if you are having problems with your energy levels, then read on to find out how sugar might be making you feel drained! 

How does Sugar make me feel tired? 

You may be experiencing a “sugar crash.” 

One of the most common ways we experience fatigue from eating sugar is the notorious sugar crash. A sugar crash is essentially a massive drop in energy shortly after consuming many refined carbohydrates (aka sugar) (2). To understand this, it is good to know what happens in your body after consuming sugars. Very quickly your blood sugar spikes (also known as hyperglycemia), which causes your body to release insulin. Insulin is a hormone that signals cells to “open up” and let the sugar into the individual cells to be broken down and used for energy. 

The problem is when we eat too much sugar at once – this causes the body to release an especially large amount of insulin. When there is too much insulin, what happens is that too many cells absorb your blood sugar at once. This then causes a considerable drop in blood sugar. Low blood sugar (anything below 70 mg/dL) makes you feel sleepy/tired because the brain has little to no fuel to keep it working. Therefore, keeping your blood sugar levels steady throughout the day is one way to ensure your energy levels remain stable too! 

Sugar might be messing up your Sleep 

Sleep is one of the most critical processes in the body. When we sleep, we go through different stages. The REM (rapid eye movement) phase of sleep is when we dream, and it is also essential for our brain health. During this phase, the brain “stores” memories from your day and removes toxins and other hazardous compounds from itself (3). This is also the deepest part of the sleep cycle, which means your muscles and body are healing themselves to prepare for the day ahead. 

Recent studies show a correlation between eating high amounts of sugar and restlessness when sleeping (4). Those who ate more sugar found that they could not fall and stay asleep compared to those on a low-sugar diet. They found that these individuals were also spending less time in the REM phase of sleep at night – meaning they were losing out on the most restful sleep they could be having. There is also evidence that shows sugar disrupting hormonal patterns in the body, impacting our ability to have restful sleep. Eating sugar (especially before bed) causes some individuals to release the hormone ghrelin while they sleep. Ghrelin is the hunger hormone, which is why those participants found themselves waking up in the middle of the night with cravings for food (5). If you find yourself feeling tired all the time, then sugar may be hurting your sleep health and making you feel sleepy! 

When you Eat Sugar, You Eat Empty Calories 

Sugars and other refined carbohydrates are what many people call “empty calories”(6). Empty calories can also be those that come from solid fats. These calories are considered empty because they add calories to your food while contributing little to no nutrients. While calories themselves do offer our bodies some energy, we also rely on various key nutrients to fuel us. Vitamins and minerals help our cells conduct all sorts of processes that allow our bodies to operate correctly. Without them, we would be unable to break down and harness the food we eat into energy. Because vitamin deficiency can lead to fatigue, a balanced diet is key to your health and maintaining your energy levels over time. 

Who is More Prone to Low Energy From Eating sugar? 

Although sugar can zap the energy out of any healthy person, some individuals are especially prone to this kind of fatigue. Sugar can have adverse effects on people with specific pre-existing health conditions. 

1: Sugar and ADHD 

There are many people with ADHD that feel extra sleepy after eating sugar. This is because consuming sugar causes a large spike in blood glucose, which also stimulates a spike in serotonin (7). This serotonin overload can cause drowsiness and fatigue, especially for those with ADHD (as they are more sensitive to changes in serotonin levels). Serotonin has various functions in the body, including the regulation of our wakefulness, which is why a sudden change in serotonin could cause fatigue.

Sugar consumption also affects those living with ADHD because of the way it impacts vitamin B6 levels. Vitamin B6 is partially responsible for the breakdown of carbohydrates (such as sugar) into glucose, which is the exact molecule that cells use to produce energy. High amounts of sugar cause cells to require higher than average amounts of the vitamin to break the sugar down. When there is an insufficient amount of B6 in the body, it leads to low energy feelings, especially for those with ADHD (8). 

2: Sugar and Diabetes 

People who struggle with diabetes have a resistance to the hormone insulin. This resistance means that when blood sugar rises and the body releases insulin, the body cells are unable to recognize the insulin – therefore the cells do not take in the sugar to be broken down into energy. The reason people with diabetes often feel incredibly sleepy or fatigued is due to the high blood sugar caused by insulin resistance. Because the cells never absorb any of the sugar, the blood sugar of diabetics remains high long after the sugar was consumed. That build-up of blood sugar, or hyperglycemia, causes inflammation in the body (9). The inflammation causes monocytes, a special kind of immune cell, to flood the brain. This response causes the brain’s activity to slow down, which leads to that sleepy feeling. The inflammation also triggers an immune response, which requires a lot of energy from the body over time. Inflammation alone is a known cause of chronic fatigue – which is why the inflammation experienced by diabetics causes them to experience exhaustion so easily (10). 

3: Sugar and Pregnancy 

Another condition that makes one especially prone to fatigue after consuming sugar when pregnant. Pregnant women commonly develop what is known as gestational diabetes. Gestational diabetes is a kind of pre-diabetes that develops during pregnancy and goes away once the pregnancy ends. Women experiencing gestational diabetes are not entirely resistant to insulin; however, insulin tends to be less effective in the body during this time (11). Therefore, women with gestational diabetes are more prone to inflammation from high blood sugar like people with type I and II diabetes (see above), causing them to feel incredibly tired after consuming refined carbs.

Try a Sugar-Free Swap 

Here at FAVES, we know how much harm sugar can cause the body. Because there are so many places sugar gets added to our diets, it is good to have healthy alternatives that satisfy your sugar cravings without sugar’s adverse effects. We sweeten our healthy candy with monk fruit. This all-natural sweetener comes from the monk fruit plant, and it is a zero-calorie sugar alternative. Monk fruit tastes almost exactly like traditional white sugar, but you can eat it without it draining all of your energy after! Making healthy swaps in our diets allow us to indulge in the kinds of foods we like, while being more protective of our health.

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