I often notice your dietary advice is to eat carbohydrate as fuel for cycling. I have to disagree as I?ve found fat and protein works far better and enables me to avoid bonking altogether. There?s lots of good science behind this, so aren?t the carbo-loaders becoming the dietary equivalent of the Flat Earth Society?

Fergus Craig, email

There has been a fair amount of study looking at the effects of modifying the traditional high carbohydrate diet favoured by athletes, to a lower carbohydrate or even high-fat diet and a meta-analysis was published in 2005 in the International Journal of Sports Nutrition.

It indicated that test subjects on a diet high in carbohydrates exercised longer until exhaustion.

However, it also indicated that this area was difficult to analyse, with differing results for those exercising at different intensities (from 65 to 90 per cent Vo2max) and consuming diets with differing amounts of substrates (high fat diets ranging from 31 per cent of the diet to 84 per cent, and high carbohydrate ranging from 53-90 per cent).

There is much evidence, however, that supports high carbohydrate diets for optimal training and performance and also some evidence to support the hypothesis that due to training adaptations favouring utilisation of fats, a diet higher in fat may also have its advantages.

However, most of the studies on higher fat diets have looked at sub-maximal exercise capacity and have only shown an effect when intake is as high as 76 per cent of calories (from fat).

The severe increases in fat may be difficult to achieve outside a laboratory and could also have a negative impact on levels of cholesterol and health.

In fact, studies have indicated that low glycogen (carbohydrate stores) are strongly linked with a poor immune system.

In addition, for optimum performance we need to be able to train and race well at higher intensities, which carbohydrate allows us to do.

Carbo-loading itself has now become a thing of the past, as the science recognises that, as long as athletes replace the stores of carbohydrate they use after exercise and in moderate portions in their meals, there is no need to load the body prior to events.

Scientific thought in this area is continually moving. If it reaches the stage where serious research indicates positive changes in an athlete?s performance at high exercise intensities on low carbohydrate diets (which it does not at present), then the common

recommendations will once again change.

Lynn Clay

Nutritional expert, former runner and expert on nutrition and exercise