Sugar tastes great for a reason: we evolved to enjoy it at a time when honey was a rare, energy-rich treat and we spent much of our time chasing after antelope. Now that sugar is easy to get and we are less active, that preference works against us. Many people consume far too much, leading to poor health. But is sugar inherently bad, aside from providing empty calories?
The idea promoted by some influencers that you should “flatline” your blood sugar response is completely unnecessary. “When we taste sugar, the body starts reacting the moment sweetness touches the tongue,” says Dawn Menning, a registered dietitian with the health app Nutu. “The brain recognizes it as a quick energy source and activates the reward system, releasing dopamine, the feel-good chemical that makes it so appealing.” Interestingly, not everyone experiences sweetness the same way. A 2015 study comparing siblings’ perceptions of sugar and sweeteners found that identical twins had more similar taste sensitivity than fraternal twins or non-twin siblings. Researchers concluded that genetics account for about 30% of the variation in sweet taste sensitivity—though it’s unclear if this affects how much we actually eat.
What happens after that first taste depends on the type of sugar. Glucose, found in table sugar, sweets, and starchy carbs, has slightly different effects than fructose, commonly found in fruit and juice. “Glucose triggers the pancreas to release insulin, a hormone that helps remove glucose from the bloodstream and store it where needed,” explains Sarah Berry, a nutrition professor at King’s College London and chief scientist at Zoe. “That could mean storing it as glycogen in the muscles or liver for energy, or converting it to fat.” Fructose, on the other hand, doesn’t prompt insulin release. “It goes directly to the liver, where it can also be stored as glycogen—or, if consumed in excess, converted to fat.”
Both types of sugar, when overconsumed, can raise triglycerides—a type of fat in the blood. While triglycerides are essential for energy, high levels increase the risk of heart disease, stroke, and pancreatitis. Fructose may be more concerning for those at risk of fatty liver disease, while glucose is a bigger issue for people with insulin regulation problems. Which one to watch more closely depends on your lifestyle and genetic predispositions.
“We also know that repeated, excessive insulin spikes can increase inflammation,” Berry adds. “Inflammation isn’t inherently bad—it happens constantly in our bodies—but when it’s chronic and excessive, it becomes problematic.”
Incidentally, the “sugar rush” is a persistent myth. A 1995 meta-analysis of studies on children concluded that sugar does not affect behavior or cognitive performance, suggesting parents’ strong beliefs may stem from expectation and association. A more recent 2019 meta-analysis found no mood-boosting effects from carbohydrates (including sugar) and noted that sugar was linked to higher fatigue levels.”Fatigue and less alertness compared with the placebo within the first hour after ingestion.” But even if our sugar-crazed kids are just acting up due to the placebo effect or because they’re at a party, another issue is what happens after the insulin spike fades and we experience a corresponding drop.
A 2019 study found no mood-boosting effects from sugar.
“We know from our Zoe Predict research that if people experience that dip, they feel hungrier and tend to eat about 80 more calories at their next meal, and 320 more calories over the course of the day,” says Berry. “So if you have a breakfast that’s just carbs, it’s very likely to cause a dip, and you’ll end up eating more later.”
This means it’s not just about how much sugar you eat, but also when you eat it and in what context. “We know blood sugar response is better in the morning because you’re more insulin-sensitive compared to the afternoon,” says Berry. “But our bodies also handle sugar better when it’s part of a balanced meal with heart-healthy fats and proteins. By the way, the idea of trying to ‘flatline’ your glucose response—as some influencers suggest—is completely unnecessary. A rise in blood sugar is a normal response to eating. We just need to make sure it isn’t excessive.”
So what’s the takeaway? As a nation, we definitely eat more sugar than we need. A recent study by the Oral Health Foundation found that 84% of us eat at least one sugary snack daily, with 79% having up to three every day. It’s wise to eat less, but there’s no need to demonize or eliminate sugar entirely. Just enjoy it in moderation, preferably not too late in the day, and ideally alongside some fiber, healthy fat, or protein.
If you’re thinking of avoiding sugar by switching to sugar substitutes, that might not be the perfect solution either. It was once thought that artificial sweeteners could spike insulin or trick hunger hormones, but that doesn’t seem to be the case. Instead, the issue may lie elsewhere.
“There’s emerging evidence that sweeteners like saccharin and sucralose can affect your oral and gut microbiome,” says Berry. “More research is needed to understand if there are long-term effects on health outcomes like blood pressure, insulin resistance, and body weight. But it’s not a free pass.” Recent research also suggests some sweeteners may be converted to fructose in the body, triggering effects similar to regular sugar.
Until we know more, get your sweetness from sugar—that’s what we’ve evolved to do. But remember: our paleolithic ancestors didn’t have as much access to sugar as we do, and they likely moved around a lot more.
Frequently Asked Questions
FAQs Sugars Effects on the Body Preventing Energy Crashes
BeginnerLevel Questions
1 What exactly is an energy crash after eating sugar
An energy crash often called a sugar crash is a sudden feeling of fatigue shakiness or brain fog that happens a little while after consuming a lot of sugary food or drink Its your bodys reaction to a rapid spike and then a sharp drop in blood sugar levels
2 Why does sugar give me a quick energy boost at first
When you eat simple sugars they are absorbed into your bloodstream very quickly This causes a rapid spike in your blood sugar which your body uses for immediate energy creating that initial rush or burst of alertness
3 What are the main negative effects of too much sugar on the body
Consistently high sugar intake is linked to several issues weight gain increased risk of type 2 diabetes and heart disease tooth decay inflammation and can contribute to fatty liver disease It also disrupts your natural energy levels leading to crashes
4 How can I tell if Im having a sugar crash
Common signs include feeling suddenly tired irritable or unable to concentrate craving more sugar feeling shaky sweaty or anxious and experiencing headaches
5 Whats a simple first step to prevent these crashes
Pair sugary foods with protein fiber or healthy fats For example have an apple with peanut butter instead of just a candy bar This slows down sugar absorption and leads to a more stable energy release
Advanced Practical Questions
6 Is all sugar bad or are some types better than others
Its more about the source and how its consumed Naturally occurring sugars in whole fruits and dairy come with fiber water and nutrients so they affect your body more slowly Added sugars are the main culprits for negative effects and crashes because theyre concentrated and easy to overconsume
7 Whats happening in my body during a sugar crash
After a sugar spike your pancreas releases a large amount of insulin to move sugar from your blood into your cells Sometimes it overcorrects removing too much sugar too quickly This rapid drop in blood sugar is what
