20th June 2014
The simple answer is no. People who work out regularly respond differently to sugar than those who don’t. For starters, your body produces less insulin (the hormone responsible for shunting glucose from the bloodstream to the muscles) after getting a sugary hit. This is one of the many ways the body adapts to exercise: it becomes more sensitive to insulin. In other words, you need less insulin to do the same job and your body learns to handle sugar more efficiently. Research has shown that exercise is one of the most effective ways to improve blood glucose levels in people with type 2 diabetes.
What’s more, fructose (which makes up half of sucrose) is far less ‘damaging’ when you exercise. When non-exercisers consume high levels of fructose, the liver responds by releasing fats into the blood stream. But according to a new study, this doesn’t happen in people who exercise. After 2 weeks of consuming an extra 75g fructose a day, inactive participants had 88% higher triglyceride levels and signs of higher inflammation following a test meal. But when the same participants were active these markers did not exist.
Exercise, it seems, blunts the negative effects of fructose, preventing the rise in blood fats (and the associated cardiovascular risk) that would normally occur after eating lots of fructose. That’s because the body increases its production of an enzyme called lipoprotein lipase, which enables your body to absorb those fats that are circulating in your bloodstream and then use them for energy.
Of course, all this isn’t a license to fuel your workouts with doughnuts and cookies. Far from it. You still need to keep an eye on total calories – excess calories from sugar can be turned into fat – and stay within sensible limits.
So how much sugar is OK? There’s no sugar recommendation for athletes although it would be wise to stick close to WHO recommendations for the general population (10% of daily calories). This would equate to 75g added sugar (excluding sugars in fruit, veg or milk) for those consuming 3000 calories a day.
The bottom line is that people who work out regularly don’t need to worry unduly about sugar (sucrose) or fructose. Sugar doesn’t have the same effect on active people as on the slothful. My preference, though, is always ‘real’ food over supplements – bananas or dried fruit rather than gels, chews or bars during exercise lasting longer than 60min. Afterwards? A Super Flapjack or Chocolate Chip Oat Cookie would be a tasty way to restock glycogen stores.
More information: Food For Fitness (4th edition)