Our love for sugar is written in our DNA, a leftover from a time when energy-dense foods like honey were rare treasures. Today, that evolutionary sweet tooth is a double-edged sword, contributing to health issues as our consumption soars and activity levels fall. But what exactly does sugar do inside us, and how can we manage its effects?
The Body's Sweet Reaction: From Tongue to Bloodstream
The moment sugar touches your tongue, your brain recognises it as a quick energy source, triggering the release of dopamine, the feel-good chemical. This reward system makes sweetness intensely appealing. Interestingly, genetics play a role in how we perceive it; a 2015 study on twins found genetic factors account for roughly 30% of the variance in sweet taste sensitivity.
What happens next depends on the type of sugar. Professor Sarah Berry, a nutrition expert at King's College London and chief scientist at Zoe, explains the key difference. "Glucose, from table sugar and starchy carbs, prompts the pancreas to release insulin. This hormone helps remove glucose from the blood, storing it as glycogen in muscles and liver or converting it to fat."
Fructose, commonly found in fruit and juices, takes a different path. "It heads directly to the liver," says Berry. "There, it too can become glycogen or, if consumed in excess, be converted into fat."
Beyond the Calories: Inflammation, Fat and the Myth of the Rush
Both sugars, when over-consumed, can increase blood triglycerides—a type of fat linked to higher risks of heart disease and stroke. While fructose is a particular concern for fatty liver, glucose is more problematic for those with insulin regulation issues.
Professor Berry highlights another consequence: "If you have an excessive and repeated insulin peak day in and day out, it can increase levels of inflammation." While inflammation is a normal bodily process, chronic, excessive inflammation is believed to underpin many health problems.
The idea of a 'sugar rush' energising children is a persistent myth. A landmark 1995 meta-analysis concluded sugar does not affect children's behaviour or cognition, attributing parents' beliefs to expectation. A 2019 review further found carbohydrates offered no mood boost, instead linking them to increased fatigue within an hour of eating.
Managing the Slump: Timing, Balance and Sweetener Warnings
The real issue often comes after the insulin peak subsides. "Our research shows if people experience a blood sugar dip, they feel hungrier," notes Berry. "They tend to eat around 80 more calories at their next meal and 320 more over the entire day." A breakfast of just carbs is a common culprit.
The solution isn't necessarily to eliminate sugar but to consume it wisely. Berry advises pairing it with heart-healthy fats, protein, or fibre to create a more balanced blood sugar response. Timing also matters, as bodies are more insulin-sensitive in the morning than the afternoon.
For those considering artificial sweeteners as a simple swap, caution is advised. Emerging evidence suggests sweeteners like saccharin and sucralose may affect oral and gut microbiomes. Recent research also indicates some sweeteners might be converted to fructose in the body, mimicking sugar's effects. "It's not a get out of jail free card," Berry concludes.
The statistics underscore the need for moderation. A study by the Oral Health Foundation found 84% of Brits eat at least one sugary snack daily, with 79% consuming up to three. The key takeaway is to enjoy sugar mindfully—preferentially earlier in the day, as part of a balanced meal, and remembering our ancestors certainly didn't have it so readily available.
