Kenyan distance runners famously drink only sweet tea before a long morning run and whilst this extreme form of fasted training may not be for you, there are things that the average cyclist can learn from the principles of low carb training.

The concept of low carbohydrate, or even fasted training, is hardly new, indeed, cyclists have utilised this form of training for over a century. And, as is so often the case, where athletes lead, scientists follow and modern techniques have allowed us to examine the effects of fasted training to see where benefits truly lie.

And, so to a summary of the science behind it.

The increased use of fat as fuel, spares your limited muscle carbohydrate stores, and so enables you to train and race for longer without hitting the wall (or bonking). The most obvious biological effects are seen inside your muscle cells as an increase in the number and size of mitochondria (commonly described as the powerhouse of the cell) which use oxygen to release energy from fat and sugars. Nutrition science has established that it is a lack of carbohydrate that stimulates these changes in the cells.

However, to make the most of your training you need all four macronutrients: water, protein, fat and carbohydrate; at the right time and in the right amounts. Your muscles will use most of their carbohydrate stores in around 120 minutes of continuous exercise such as a zone 2 bike ride. After this, your muscles rely on carbohydrates released from the very limited stores in the liver, and stored fat from within the muscle and all over the body.

The benefits of fasted training will be seen after this 2 hour period, so you can eat and drink carbohydrates during training without ruining the session given that digestion and absorption of anything you eat or drink will take at least 20 minutes. Indeed, you can even start to fuel normally at around the 90-minute mark in order to make the most of your training.

If you use low carbohydrate training wisely you can maximise your training adaptations without compromising your health or training intensity. Adjusting your carb intake to match your training will take your performance to new heights.

Top Tips for Optimising Low Carb Training

  1. You don’t have to go to the extremes of fasted training to benefit from the effects of low carbs – you can eat proteins and fats without impacting on the results
  2. Low carb training doesn’t have to mean no carb training – you can afford a small amount and still benefit
  3. Low carb training increases your muscles’ ability to use fat as fuel so you can keep exercising for longer – building this type of training into your regime is important if this is your goal
  4. Low carb training only works at low intensities – adopt it when your session is something like a zone 2 ride
  5. Overdoing it on low carb training can stress your body – I don’t advise doing more than three sessions a week on low carbs and only one of those should be running as this has a higher body stress level compared with cycling or swimming
  6. After around 90 minutes of low carb training you can fuel with carbohydrates and still benefit from the effects

The potential benefits of low carb training are significant for an endurance athlete and is a vital part of improving racing performance provided it is managed within these guidelines.

For more nutrition tips, visit me on Instagram or Twitter @DavidStarrPN or contact me for 1-2-1 performance nutrition coaching by emailing me at

David Starr, Vitfor Performance Nutritionist, has been supporting athletes for over 20 years. By taking a bespoke approach with individual recommendations for each unique athlete, he can help you produce exceptional results and maximise your potential. From specific race plans, to session-by-session fuelling and recovery programs, David provides an elite level of service to every client.

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