A state where your body switches from using carbohydrates to burning fat for energy. You need to be carbstarved, generally eating less than 50 grams each day, mostly through fruits and vegetables, to achieve it. People who follow a ketogenic diet get roughly 70 per cent of their kilojoules from fat, 25 per cent from protein, and 5 per cent from carbs. WHO’S INTERESTED
Endurance junkies love the idea, because even lean athletes have significant fat stores to burn. So they could theoretically enjoy endless energy and never bonk again. People have also been attracted to it as a weight-loss strategy.
It’s restrictive, difficult to do properly, and not proven to improve endurance – it may even hinder it. And because muscles burn glycogen (stored carbs) during high-intensity efforts, some athletes struggle to produce power on the diet (that’s why some strategically eat starchy carbs during key training and racing blocks). You also risk long-term nutrient deficiencies.
You can buy ketone supplements. “These can produce ketosis even when blood glucose levels are normal, which potentially improves exercise performance,” says Robert Child, PhD, of Elite Sport Group in the UK. The problem: “The taste is so bad it could prevent you from consuming enough of the carbohydrate-rich foods that are essential for attaining optimal endurance performance,” he says.