Key takeaways:
Many people think that eating sugar will give them a sudden burst of energy, or a “sugar high.” But this common belief is more myth than reality.
Feeling tired or sluggish after eating carbohydrates is common, but researchers haven’t established exactly why it happens. It doesn’t necessarily mean your blood sugar has dropped too low.
Eating sugar doesn’t make children hyperactive, despite what many parents believe.
Most people have used the terms “sugar high” or “sugar crash” at some point. But what do these terms really mean? If you feel tired or sluggish after a meal, is low sugar to blame? And do high-carb meals give you a burst of energy by increasing your blood sugar?
We’ll break down what happens when your body gets a sudden intake of sugar, explore the science behind these popular beliefs, and look at what the research says about sugar’s effects on children.
What is a sugar crash?
A sugar crash isn’t a medical diagnosis. People use the term to describe feeling tired, sluggish, or less focused after eating foods high in sugar or carbohydrates. One common explanation is that these foods cause blood sugar to rise quickly and then fall, leading to a dip in energy. But feeling tired after eating doesn’t necessarily mean your blood sugar has dropped too low.
What does a sugar crash feel like?
Reported symptoms of a sugar crash include:
A sudden feeling of tiredness
Brain fog
Trouble concentrating
Jitteriness
Mood changes
Headaches
Are sugar crashes real?
Yes and no. Feeling sluggish after eating is real, but it doesn’t necessarily mean your blood sugar has crashed.
Studies have found that people tend to feel more tired and less alert in the hour after eating carbohydrates. Researchers don’t understand exactly why carbs may lead to fatigue. Since blood sugar normally rises and falls after eating, it’s possible that the symptoms are related to blood sugar coming down after an initial spike. But there isn’t evidence that this is the cause.
And carbohydrates aren’t the only foods that can leave you feeling sluggish. High-fat meals can also make you more exhausted after eating. Other factors, such as time of day and larger meals, can also make you feel tired after eating.
So, while feeling tired after eating carbohydrates is a real experience, it doesn’t necessarily mean that your blood sugar is to blame or that it has dropped too low.
How is a sugar crash different from hypoglycemia?
For most people experiencing sugar crash symptoms, blood sugar stays within a normal range after a meal. Hypoglycemia is when your blood sugar drops below normal levels. Symptoms of true hypoglycemia are usually more serious and intense than what people call a “sugar crash.”
In rare cases, people may develop hypoglycemia 2 to 5 hours after a meal. This is known as postprandial hypoglycemia. It can occur in people taking certain diabetes medications or after bariatric surgery. But it’s rare. Feeling tired or shaky after eating doesn’t necessarily mean your blood sugar is low.
Symptoms of hypoglycemia include:
Fast heartbeat
Anxiety
Irritability
Sweating
Confusion
Difficulty concentrating
Fainting
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If you frequently have symptoms that could indicate low blood sugar, talk with a healthcare professional. For symptoms of confusion, fainting, or severe symptoms, seek immediate medical attention.
What is a sugar high?
A “sugar high” is the term people use to describe a sudden burst of energy, excitement, or hyperactivity after eating sugary foods. The idea is that eating foods high in sugar or carbohydrates causes blood sugar to rise quickly, giving you a temporary boost in energy. People often associate sugar highs with children after eating candy or other sweets. But research hasn’t found that sugar reliably boosts energy or causes hyperactivity.
What’s going on when you experience symptoms of a sugar high?
The idea of a sugar high is a myth. For most people, blood sugar returns to normal shortly after a meal.
When you eat foods that contain glucose, your body responds quickly by releasing insulin. This hormone pushes that glucose into your cells, keeping your blood sugar within the normal range. So, it’s rare to reach high levels of blood sugar. And a recent meta-analysis looking at over 31 studies concluded that eating carbohydrates didn’t have any effect on mood and didn’t lead to an energy boost.
This may not match with your experience. Maybe you really feel like you get a burst of energy from eating a favorite doughnut. So, what’s going on? Enjoying a sweet treat can feel rewarding, and your brain’s reward pathways can be activated by eating something you love. In fact, sugar may light up pleasure centers in a way that’s similar to other addictive substances. But feeling energized after eating something you enjoy doesn’t necessarily mean sugar has increased your energy levels or raised your blood sugar levels above normal.
What does it mean to have high blood sugar?
High blood sugar (hyperglycemia) means that the level of glucose in your blood is higher than normal. It’s most commonly associated with diabetes or prediabetes. These conditions can happen when your body doesn’t make enough insulin or can’t use it effectively. Certain medications, including steroids, and other medical conditions can also contribute to high blood sugar.
In people without diabetes, blood sugar usually stays within the normal range. And high blood sugar is different from what people call a sugar high. The symptoms of hyperglycemia are actually not the same as the symptoms people usually associate with a sugar high.
Hyperglycemia can lead to symptoms like:
Increased hunger or thirst
Abdominal pain
Confusion
Blurred vision
If you have these symptoms, a healthcare professional can check your blood sugar levels with a quick blood test to figure out if you might have hyperglycemia. If your blood sugar is high enough, glucose may also show up in your urine.
If you have diabetes and develop vomiting, abdominal pain, confusion, or fruity-smelling breath, seek urgent medical care.
Can sugar make people (and especially children) hyperactive?
Probably not. At a birthday party, parents might swear that cake and desserts are making their children bounce off the walls. But in reality, other factors are likely at play.
Multiple studies looking at the link between sugar intake and hyperactivity have failed to show a connection. For example, one study looked at 12 double-blind, placebo-controlled sugar challenges in both children with and without attention-deficit hyperactivity disorder (ADHD). The results showed no increase in hyperactivity or behavior problems in the children who ate candy or chocolate.
You may be thinking, “That’s impossible! You haven’t seen my child hyped-up on candy!” But consider this: Could the belief that sugar makes kids hyper affect how adults think their kids are acting?
One study explored this idea by comparing two groups of moms. One group was told that their sons drank a large quantity of sugar. The other group was told their sons had a sugar-free beverage. In fact, all the children actually drank the same sugar-free beverage. The moms who believed that their children had sugar rated them as significantly more hyperactive. The researchers also noticed that these moms were more controlling and critical of their sons’ behavior during the study.
Can sugar affect a child’s behavior or cognitive skills?
Many people believe that sugar causes bad behavior, trouble concentrating, and poor sleep in children. But the science just doesn’t support these claims. Researchers looking at dozens of studies and hundreds of children haven’t found a link between sugar intake and children’s behavior or cognitive performance.
When it comes to ADHD, the research is more complex. Children who drink high amounts of sugary beverages or eat diets high in refined sugar are more likely to be diagnosed with ADHD. But the exact connection isn’t clear. Researchers don’t know whether children with ADHD are more likely to seek out sugar-rich food or whether sugar itself might trigger ADHD in susceptible individuals.
Can you prevent a sugar high or a sugar crash?
You can’t always prevent feeling tired after a meal. And no single strategy can prevent every post-meal dip in energy. But a few eating habits can help support steadier blood sugar levels after eating.
Here are some tips to try:
Pair carbs with protein and fiber. Adding protein, fat, and fiber to meals that contain carbs may help keep blood sugar levels more stable after a meal.
Eat more slowly. Fast eating is associated with bigger spikes in blood sugar after a meal.
Eat fewer highly processed foods. Swap out highly processed foods for more whole foods and minimally processed foods that are rich in fiber and protein.
Eat dinner early. There’s some evidence that this may lead to more stable blood sugar levels the next day.
Exercise 30 minutes after a meal. Light or vigorous exercise after meals can lower blood sugar spikes. Even a short walk can help.
The bottom line
A “sugar high” may feel real, but research hasn’t found that eating sugar reliably boosts energy or makes children hyperactive. A “sugar crash” is more complicated. People can feel tired or sluggish after eating carbohydrates, but researchers haven’t established exactly why. For most people, these symptoms don’t mean their blood sugar has dropped too low.
Low blood sugar (hypoglycemia) after a meal can happen, but it’s different from the everyday tiredness people often call a sugar crash. Whether or not sugar causes a noticeable high or crash, eating a balanced diet and limiting added sugars can support your overall health.
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