We need sugar to fuel our muscles while exercising but we also know that consuming too much can harm our health. The average person consumes 50g (about 12 teaspoons) of sugar* a day, that’s almost double the NHS’s recommended daily maximum (30g, or 7 teaspoons). Energy drinks, gels and bars are crammed with sugar – a single energy bar can contain more than half of the recommended daily limit – so could you unwittingly be storing up future health problems?
Sugar + performance
Sugars are short-chain carbohydrates, and that’s exactly what fuel most of our workouts. ‘When we exercise, we use carbohydrate as one of the main fuels,’ explains Dr Javier Gonzalez, Professor of Nutrition and Metabolism at the University of Bath. ‘But we can quickly run out of stored carbohydrate in the liver and muscles, especially when that exercise is of higher intensity or prolonged duration. Sugar intake, in the form of sports drinks, bars and gels, is one of the ways we can help prevent depletion of glycogen and provide fuel to keep us going.’
Alternatives to sugar during exercise?
In a study published in the Journal of Applied Physiology, a team of Illinois University scientists found no differences in the performance of endurance cyclists who ingested pureed potatoes and those who used energy gels at recommended amounts of about 60 g per hour during a two-hour cycling challenge.
‘When you’re consuming less than 60g carbohydrate per hour, the source and format of that carbohydrate doesn’t matter. Any rapidly-digested carbohydrate – potatoes, rice, bananas – will do the job,’ explains Dr Gonzalez. ‘But when you’re exercising hard, consuming more than 60g per hour, that’s when sugars can really play a useful role, especially in liquid or gel form.’
The downside: gels, bars + drinks
Studies have shown that athletes who regularly consume energy drinks, gels and bars experience significant tooth decay and erosion. ‘These products are high in sugar and as they are usually consumed at frequent intervals during exercise, they are particularly damaging to the teeth,’ explains Professor Ian Needleman, Professor of Periodontology and Evidence-Informed Healthcare at University College London.
‘In our research with elite and Olympic athletes, we found that more than half have tooth decay at a level that requires intervention. That’s significantly more than the general population.’ Needleman’s research has also shown that poor dental health has a huge impact on performance. ‘Pain from poor oral health can affect your ability to train and compete and can even affect eating,’ says Needleman.
Health risks of sugar
Overconsumption of sugar has been linked with obesity, insulin resistance, type 2 diabetes, and cardiovascular disease. According to Gonzalez, the NHS guidelines don’t apply to athletes: ‘Within reason, there’s no upper limit on daily sugar intake for hard training athletes. There’s no real metabolic health detriment to people ingesting sugars if they are doing high levels of physical activity. If you are endurance-trained, you get chronic adaptation whereby you have greater insulin sensitivity.’
In other words, training increases your sensitivity to insulin, which means less insulin is required to move glucose from the blood into cells allows. Research shows highly trained athletes have an increased ability to process sugar compared to the average, non-active person.
Sugar in our everyday food and drink is a slightly different story. The sweetness it provides, especially when combined with lots of fat in the form of cakes, chocolates, biscuits and snacks, tastes tantalising good, perhaps even addictively so. Even so, it is not uniquely fattening. Your weight is determined by overall energy balance (calories in vs calories out), meaning that weight gain comes from excess calorie intake over weeks and months, regardless of the source.
Finding the sweet spot
As with so many things in life it’s all about balance. Grazing on sugary foods all day while sitting at your desk may not be good for health, but those same foods eaten whilst exercising offer fast- access fuel for your muscles, helping prevent fatigue and sustain peak performance. In fact, avoiding sugar could compromise your performance in high-intensity workouts and races. But there are downsides to sugar consumption, namely its corrosive effect on teeth.
Useful strategies to mitigate this risk using include switching to starchy carbohydrates at lower exercise intensities, ensuring regular tooth brushing, using higher fluoride toothpastes and employing a two-bottle strategy. The key message is reassurance: athletes don’t need to be unduly concerned about the effect of sugars on their metabolic health since regular exercise enhances insulin sensitivity and regulates blood triglycerides.
This is an abridged version of my feature in Cycling Weekly
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