Our ancient love for sugar, a vital energy source for our hunter-gatherer ancestors, is now a modern health dilemma. With honey no longer a rare find and our lifestyles far more sedentary, that innate sweet tooth is contributing to widespread overconsumption and associated health issues. But what exactly does sugar do inside us, and how can we manage our intake to prevent the infamous energy slump?
The Body's Sweet Reaction: From Tongue to Brain
Dawn Menning, a registered dietitian with the health app Nutu, explains that the body's response is immediate. "The moment sweetness touches the tongue, the brain recognises it as a quick energy source and activates its reward system," she says. This triggers a release of dopamine, the feel-good chemical, which is why sugar is so appealing.
Interestingly, genetics play a role in how we perceive sweetness. A 2015 study comparing siblings found that identical twins had more similar sweet taste perceptions than non-identical twins or other siblings. Researchers concluded that genetic factors account for roughly 30% of the variance in how sensitive people are to sweet tastes, though it's unclear if this directly influences how much we eat.
Glucose vs. Fructose: A Tale of Two Sugars
The journey of sugar in your body depends heavily on its type. Glucose, found in table sugar, sweets, and starchy carbs, has a different effect to fructose, commonly present in fruit and juices.
"Glucose prompts the pancreas to release insulin," says Professor Sarah Berry, a nutrition expert at King's College London and chief scientist at Zoe. "Insulin's job is to remove that glucose from the bloodstream, depositing it as glycogen in muscles or the liver for energy, or converting it into fat."
Fructose, however, doesn't trigger insulin release. "It goes directly to the liver, where it too can be stored as glycogen or, if consumed in excess, converted into fat," Berry adds.
Both sugars, when over-consumed, can increase blood levels of triglycerides—fats essential for energy. High triglyceride levels are linked to a greater risk of heart disease, stroke, and pancreatitis. Fructose may be a particular concern for those at risk of fatty liver syndrome, while glucose is more problematic for individuals with insulin regulation issues.
Debunking the Sugar Rush and Understanding the Real Crash
The concept of a 'sugar rush' is a persistent myth. A landmark 1995 meta-analysis concluded that sugar does not affect children's behaviour or cognitive performance, attributing parents' beliefs to expectation. A more recent 2019 meta-analysis found no mood-boosting effects from carbohydrates, noting they actually increased fatigue and reduced alertness within an hour of consumption compared to a placebo.
The real issue is the subsequent energy dip. "Our research with the Zoe Predict cohort shows that people who experience a significant blood sugar dip feel hungrier," explains Professor Berry. "They tend to eat around 80 more calories at their next meal and 320 more calories over the entire day." A breakfast consisting solely of carbohydrates is likely to cause this dip, leading to increased consumption later.
How to Consume Sugar Smarter
Managing sugar isn't just about quantity; timing and context are crucial. "Blood sugar response is more favourable in the morning due to higher insulin sensitivity," says Berry. "Our bodies also handle sugar much better when it's part of a balanced meal containing heart-healthy fats, protein, and fibre."
She dismisses the influencer trend of trying to 'flatline' glucose responses as unnecessary. "An increase in blood glucose is a normal physiological response to eating. We just need to prevent it from being excessive."
The statistics underscore the scale of the issue. A recent study by the Oral Health Foundation found that 84% of Britons eat at least one sugary snack daily, with 79% consuming up to three. The advice is not to demonise sugar but to enjoy it in moderation, preferably earlier in the day and alongside other nutrients.
The Artificial Sweetener Conundrum
Turning to sugar substitutes may not be a perfect solution. While they don't appear to spike insulin or trick hunger hormones as once feared, emerging evidence suggests sweeteners like saccharin and sucralose can affect oral and gut microbiomes.
"More research is needed to understand the long-term effects on health outcomes like blood pressure and insulin resistance," Berry cautions. "It's not a get-out-of-jail-free card." Recent research also indicates some sweeteners may be converted into fructose in the body, mimicking sugar's effects.
The take-home message is evolutionary: seek sweetness, as we are designed to do. But remember, our paleolithic ancestors had limited access to sugar and led vastly more active lives. Enjoy sugar mindfully, within a balanced diet, to maintain energy and health.
