There's been a lot of debate here recently about various versions of the low carb diet.

As far as the Paleo diet is concerned, I have no trouble with the plausibility of one of its basic assumptions, namely that the more processed food we eat, the more likely we are to run into trouble. And there's no doubt that refined carbs ar now consumed in ridiculously high volumes by very many people. So I guess I am fundamentally sympathetic to The low-carb movement.

And it probably works fine, athletically, for the pure endurance athlete. The ironman or ultramarathoner doesn't want to go anaerobic, it just burns matches they want to stay unlit. What they want to do is become as fast as possible in their endurance zone, and just tick over, conserving as much glycogen as possible and burning just enough of it to fire their fat-burning. And that is probably true of most cyclists who just want to ride around, get fitter, have a good time etc. and are rarely or never going to make threshold and supra-threshold efforts.

But if we're talking about competition, bike racing simply isn't like that. Yes, one needs a high level of endurance. But it is the nature of most races that one is alternately sprinting, recovering at speed, sprinting again and so on. In a typical race, even at my pitiful level, my HR is averaging something very close to my threshold and oscillating between max HR and, say, 90% of threshold. I'm anaerobic repeatedly and the ability to tolerate that is key to simply being able to stay with the pack.

When I dabbled with low-carb I simply couldn't do it. I couldn't train for it effectively, because I found that I couldn't complete my interval sessions and I was tired all the time. When I reverted to a "normal" carb intake of maybe 200g - 300g per day the difference was immediate, and beneficial.

So my view would be that most people would probably benefit from significantly reducing their intake of refined carbs, and that doing so is not going to compromise their performance at most recreational or endurance-based sports. But if they want to train for bike-racing, then based on my experience they are going to have to get enough carbs to fuel their efforts. That may not be a huge quantity, but it won't be negligible, either.