Mixed

Sleeping with reduced carbohydrate availability (the 'sleep-low' protocol) increases markers of fat oxidation and metabolic flexibility during subsequent exercise without compromising training intensity, but fails to augment markers of mitochondrial biogenesis compared to immediate post-exercise carbohydrate intake.

If you are an endurance athlete, you can try 'sleeping low' by eating a moderate amount of carbs before evening high-intensity training, then fasting until the next morning's steady-state ride. This will increase your body's ability to burn fat during exercise. However, do not expect this to build more mitochondria or improve your overall aerobic capacity compared to eating carbs immediately after training. It is a metabolic tool, not a magic bullet for structural adaptation.