6 sugar rules that will change your attitude towards food

Back in 2004, an international team of sports scientists led by Vincent Onywera of Kenyatta University, Kenya, spent a week monitoring everything a group of 10 top Kenyan male distance runners ate and drank. To the surprise of no one, the researchers discovered that the diet of these athletes was quite good overall. They ate plenty of vegetables and healthy starches (mainly cabbage, beans, cornmeal and potatoes), a limited amount of meat (mostly beef) and almost nothing processed.

There was, however, one notable exception to the wholesomeness of the regular menu of these runners: a whopping 20 per cent of their calories came from refined sugar. No, they weren’t snacking on sweets or swilling soft drinks all day. They just drank a lot of tea, which Kenyans like to take loaded with milk and table sugar. Still, 20 per cent is a lot – far more than the 12 per cent contribution that refined sugars make to the diet of the average adult in the UK. This is, of course, considered to be too high in sugar.

In the 13 years since this study was conducted, Kenya’s elite runners have continued to fuel their bodies with super-sweet tea, something I saw for myself when I visited the country in 2015 to research my new book, The Endurance Diet. These Kenyan elites, have, of course, continued to perform exceptionally well in competition. Meanwhile, growing numbers of recreational runners in other parts of the world have striven to eliminate sugar from their diet and even to avoid using sugar-containing products during training and competition. These efforts are based largely on a recent wave of negative news reporting on sugar, which has been labelled a ‘drug’ a ‘toxin’ and ‘poison’. But if the best runners on earth are among the heaviest sugar consumers, can it really be so bad?

Not according to the experts. ‘Sugar has become the scapegoat du jour in our public discourse about nutrition,’ says Dr David Katz, President of the American College of Lifestyle Medicine. ‘This is fine on one level, because many of us eat too much of it and would benefit from eating less. On another level, however, this kind of absolutist, either/or thinking about nutrition also carries negative consequences.’

For runners, the consequences of an excessive fear of sugar may include fitness stagnation resulting from inadequate carbohydrate intake (sugar is a carb) and also poor race performance resulting from failure to take advantage of the performance-enhancing effects of sugar intake during competition.

The truth about sugar is that it has pros and cons. On the plus side, it makes food taste good and it provides quick energy during intense activity. On the minus side, overconsumption of sugar has been proven to lead directly or indirectly to weight gain, insulin resistance and various cardiovascular disease risk factors. Enjoying the benefits of sugar while avoiding its negatives requires a balanced and smart approach to sugar consumption. To find this balance, follow these six science-based sugar rules.

Rule 1/ Don’t worry about natural sugars

There are two basic categories of sugar: natural and refined. Natural sugars are, as the name suggests, naturally present in foods. Examples are lactose in milk and fructose in fruit. Refined sugars are extracted from natural foods and then added to other foods and drinks to make them sweeter. Examples are high-fructose corn syrup, which is used in soft drinks, and sucrose (or table sugar), an ingredient in many desserts.

Some nutrition experts (and would-be experts) caution people to avoid natural and refined sugar sources alike, on the grounds that ‘sugar is sugar’. Consider this quote from a popular fitness website: ‘Some studies suggest fructose, the main type of sugar found in fruit, can even be more harmful than other sugars (namely, glucose). Fructose has even been linked to increased belly fat, slowed metabolism and overall weight gain.’

It’s true that fructose is the main type of sugar found in fruit. It’s also true that fructose appears to be more harmful than other types of sugar – but only when it’s not contained in fruit. Whole fruit itself, however, is one of the healthiest things you can eat. A recent study at Harvard University, US, found that a high intake of fruit was more effective than a high intake of vegetables in preventing weight gain.

2/ Do eat refined sugar in moderation

Anti-sugar activists such as Gary Taubes, author of The Case Against Sugar, have popularised the idea that refined sugar, especially fructose, is uniquely potent as a contributor to weight gain and metabolic diseases. The biochemistry underlying this argument is complex, but the basic idea is that 100 calories of sugar are more fattening that 100 calories of anything else you might eat.

The problem with this idea is that most of the scientists actually doing the research it’s supposedly based on (Taubes is a science writer, not a scientist) don’t endorse it. ‘If you don’t overeat sugar, it doesn’t have any special effect compared to any other form of carbohydrate,’ says Stephan Guyenet, a neurobiologist and author of The Hungry Brain.

Guyenet points to the work of John Sievenpiper, a nutrition scientist at the University of Toronto and one of the world’s leading experts on the health effects of sugar consumption. Sievenpiper’s research has yielded compelling evidence that refined sugar wreaks havoc on the body only when high levels of sugar consumption (again, fructose in particular) are combined with general overeating.

READ: 7 common post-run eating mistakes

This may explain the ‘Kenyan paradox’, as we might call it. In Vincent Onywera’s study of the diet of elite Kenyan runners, all 10 subjects actually lost weight during the week they were under observation, despite getting 20 per cent of their calories from sugar. The reason was simple: they ate fewer total calories than they burned.

So how much sugar is too much? The World Health Organization now recommends limiting refined sugar intake to 10 per cent of total calories. If you eat 2,000 calories per day, therefore, only 200 of those calories should come from refined sugar.

One can of cola contains 39g of sugar, or 156 sugar calories. A single chocolate chip cookie contains 18g, or 72 calories, of sugar. So, on a practical level, the 10 per cent rule limits you to one or two sweet treats per day. But be aware that many foods besides sweets also contain added sugars and these, too, count toward your daily limit.

In his book Salt, Sugar, Fat, Michael Moss revealed that food companies hide sugar in all kinds of foods to trick our brains into craving more of them. The list of foods to watch out for includes bread, dried fruit, hot dogs, pasta sauce, peanut butter, salad dressing, crisps and yoghurt. But avoiding the hidden sugar in these foods isn’t as easy as looking for the word ‘sugar’ on the list of ingredients. Food companies disguise the presence of sugar by giving it different names: agave nectar, brown rice syrup, brown sugar, corn syrup, dextrose, fructose, high-fructose corn syrup, maltose, sucrose and tapioca syrup.

3/ Don’t go to extremes to avoid sugar

Some popular diets encourage followers to aim far lower than the WHO standard, forbidding refined sugar completely. Since refined sugar offers no health benefits, you wouldn’t expect these diets to do any harm, but runners who go 100 per cent sugar-free often encounter unexpected negative consequences.

One such runner is Julie Benson, who was persuaded to try the popular No Sugar No Grain (NSNG) diet by a training partner. The results were disastrous. Eliminating sugar and grains from her diet left Benson feeling sluggish and lethargic, which ruined her marathon training plans. ‘I felt awful,’ she says. ‘The diet didn’t just slow me down – I could barely even run at all.’

READ: Can you run without relying on sugar?

Benson’s friend urged her to stick with NSNG, insisting she would soon adjust and start feeling better. She never did. While her struggles were more than likely the result of inadequate overall carb intake rather than lack of refined sugar specifically, Benson both felt better and performed better when she resumed eating grains and moderate amounts of sugar-containing foods.

In addition to the various physical consequences, attempts to remove all refined sugar from the diet also carry psychological risks. Benson worried constantly about eating the wrong thing while on NSNG and was racked with guilt whenever she broke a rule. Scientists at the State University of New York and Albany, and elsewhere, have shown that the stress and anxiety associated with maintaining unreasonably strict dietary standards can elevate the stress hormone cortisol, and this, in turn, may accelerate brain ageing and lead to other long-term health consequences.

Other recent research, from the University of Canterbury, New Zealand, suggests people who have a guilt-based relationship with food are more likely to binge on junk food when under stress. There is also evidence that extreme diets serve as stepping stones to full-blown eating disorders such as bulimia. For all of these reasons, it is best to aim for moderation in refined sugar intake, not total elimination of all sweets.

Rule 4/ Do break your sugar addiction (if you have one)

Sugar’s most dangerous quality is its tendency to promote overeating. According to Guyenet, sugar does this by stimulating the release of the brain chemical dopamine, which acts as a behavioural reinforcer. ‘Essentially,’ says Guyenet, ‘dopamine teaches your brain that what you just did was good and you should do it again in the same situation.’

Studies on rats have even shown that, through its action on dopamine, sugar affects the brain and behavior in ways similar to addictive drugs, a finding that has led to sensational news headlines such as: ‘Research shows cocaine and heroin are less addictive than Oreos’ (Forbes.com); ‘Sugar is “the most dangerous drug of our time” and should come with smoking-style health warnings' (Daily Mail); ‘Sugar addiction “should be treated as a form of drug abuse”’ (Independent)

Is this true? Not quite. Addiction experts say that such alarming comparisons are based on a basic misunderstanding of the nature of addiction. According to Marc Lewis, author of The Biology of Desire, any pleasurable experience can lead to addiction, and whether a person actually becomes addicted to sugar, computer games or anything else depends largely on individual susceptibility.

‘We know that most people who take addictive substances such as opiates don’t become addicted,’ says Lewis. It’s the same with sugar. Unlike hard drugs, which, for the most part, only at-risk individuals experiment with in the first place, sugar is something that every person in modern society is exposed to, and yet only a small fraction of us appear to become dependent on it.

The common (and innocent) term for a susceptibility to sugar addiction is a ‘sweet tooth’. If you have one, you probably know it, and your health and fitness may depend on breaking it. Fortunately, it is possible. Lewis recommends a practice known as scheduling, which entails making conscious decisions about what types of sweet treats you will allow yourself to consume, how much and how often, and then sticking to these decisions.

READ: 4 naturally sweet desserts

One runner who overcame her sweet tooth through scheduling is Tina Muir, originally from St Albans, and now living in Kentucky, US. In 2015, Muir was struggling to advance to the elite level with her running and concluded that sugar was holding her back. ‘I used to wake up in the morning, walk directly to the fridge and eat some chocolate,’ she recalls. ‘Two hours later, the cravings would hit again and I would have a few sweets. My lunch required a dessert, as did, of course, dinner.’

With the help of a nutritionist, Muir worked out a schedule that allowed her to eat dessert once a week and a few pieces of chocolate or sweets every other day or so. Muir lost belly fat, her sugar cravings diminished and her running improved. In 2016, she set a four-minute PB of 2:37 at the London Marathon and qualified to represent Great Britain at the World Half Marathon Championships.

Rule 5/ Don’t forget about fat

If the most dangerous thing about sugar is its tendency to promote overeating, the most dangerous thing about the vilification of sugar is that it makes people forget about other nutrients that promote overeating and are harmful when overeaten. Erica Schulte, a clinical psychologist at the University of Michigan, US, who researches the characteristics of foods implicated in addictive eating notes that added fats, such as the oils in crisps, and refined carbs other than sugar, such as the wheat flour in pizza crust, are as hard to stop eating as sugar and are especially addictive when combined with sugar.

‘There are no foods in nature that have naturally high levels of both sugar and fat,’ says Schulte. ‘We see unprocessed foods high in fat (e.g. pistachios) or sugar (e.g. bananas) but we never see the two together. This underscores that highly processed foods may be made to be artificially rewarding by containing high quantities of both fat and rapidly absorbed refined carbs.’

READ: 4 pieces of timeless nutrition advice

In 2015, Schulte and two of her colleagues asked more than 500 volunteers to rank the foods they were most likely to overeat. None of the foods rated as most addictive was high in sugar only. Three of the top six – chocolate, ice cream and biscuits – were notable for their combination of large amounts of fat and sugar. The other three – chips, pizza and crisps – contain lots of fat and refined carbs and little or no sugar.

What all of these foods do have in common is that they are processed. A truly healthy diet must moderate all highly processed foods, not just sugar. This may be one more reason why the runners in Onywera’s study were so fit and healthy despite eating large amounts of sugar. Sweetened tea was the only processed food (or drink, in this case) these athletes ate. The rest of their diet was ideal. By contrast, in the UK, most of us eat a lot of sugar, a lot of refined carbs and a lot of added fats.

Rule 6/ Do use sugar to boost running performance

Most sports drinks and gels contain sugar and many runners now avoid them for this reason. Many fear that consuming sugar during exercise will cause an ‘insulin spike’ followed by ‘a blood sugar crash’ and fatigue. Not so. ‘The idea that you get insulin spikes during exercise after consuming sugar is nonsense,’ says Asker Jeukendrup, a visiting professor at Loughborough University who specialises in nutritional biochemistry, and is founder of mysportscience.com.

Sugar delays fatigue during running by providing a source of quick energy to the muscles and nervous system. Research at Loughborough University found that runners ran a marathon nearly four minutes faster, on average, when they drank a sugar-containing sports drink than when they drank water.

Other runners avoid taking in sugar on the run because of concerns it will cause GI distress. It’s true that consuming too much sugar (and/or other carbs) can cause GI symptoms such as nausea, but says, Jeukendrup, ‘most GI problems are caused by the exercise itself. People who get GI problems always get GI problems. It doesn’t matter whether they take water or carbohydrate or nothing at all.’

In fact, sugar is less likely to cause tummy issues than other nutrients, such as medium-chain triglycerides, which runners sometimes turn to as alternatives to sugar. Another concern that runners have about sugar in sports drinks and energy gels is that it leads to weight gain. But research has shown that taking in carb calories during exercise results in lower calorie intake afterward. A study conducted at Colorado State University, US, found subjects voluntarily ate 94 fewer calories in their next meal after a workout during which they took in carbs.

‘There’s so much confusion in this area and it’s getting worse,’ says Jeukendrup. Hopefully the rules here will have brought clarity and left you free to enjoy that sugar in your pre-run tea.