Published on 1st March 2017


It is widely acknowledged that carbohydrate consumption is important for those taking part in endurance sports:1

  • To preserve stored glucose (glycogen)
  • To provide sufficient energy (calories) for training/competition
  • To prevent use of protein for energy
  • To enhance performance

In recent years, however, there has been an increased interest in the effect of training in a low carbohydrate state i.e. training following a period without food (generally overnight). It is thought that training with limited carbohydrate availability (‘train low‘) can stimulate adaptations in muscle cells to support energy production from body fat.2 By becoming efficient at utilising fat as fuel, the endurance athlete hopes to: conserve glycogen stores for the later stages of an event; reduce excess fat mass; and reduce the risk of ’hitting the wall’.

A 2015 study published in the Journal of Applied Physiology went further and investigated the approach of “train high, sleep low” as a way of encouraging these adaptations.3 The researchers found that adequate carbohydrate fuelling before an evening interval training session, followed by overnight fasting and a subsequent 1h-1h30 steady state (non-interval) training session before breakfast, increased fat burning, compared to the traditional carbohydrate feeding immediately following interval training.

It must be noted, however, that to date no research has observed enhanced performance from this approach to fuelling. Additionally, this approach places stress on the endocrine and immune systems. 


Read more articles and recipes



  1. Thomas DT, Erdman KA & Burke LM (2016). Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and athletic performance. J Acad of Nutr and Dietetics116(3), 501-528.
  2. Van Proeyen K et al (2011). Beneficial metabolic adaptations due to endurance exercise training in the fasted state. J Applied Physiol110(1), 236-245.
  3. Lane SC et al (2015). Effects of sleeping with reduced carbohydrate availability on acute training responses. J Applied Physiol119(6), 643-655.