Conventional wisdom states that you must carbo-load to maximise your performance in endurance events like running and triathlon.
Your body has a limited supply of carbohydrates, stored in the muscles and liver as glycogen that you use to fuel your races. Your performance will suffer, and you’ll “hit the wall,” i.e. experience sudden fatigue and loss of energy if it’s depleted.
This is true.
As a result, athletes have, for years, been gorging on high-carbohydrate foods in the lead-up to a race, intending to “top up” their glycogen stores.
What’s often forgotten, however, is that your body has another, more sustainable, fuel it can use during long-distance races – fat.
Burn Fat For Fuel
Unlike carbohydrates, which are very limited in supply (up to 2,000 kcal), even the skinniest of runners have a nearly unlimited amount of fat (50,000+ kcal) they can access to fuel their running.
Depending on the intensity of your running and your metabolic health, your body will have a preference for fat or carbohydrates. At low-intensity, when there is an abundance of oxygen available, you’ll burn more fat. At high-intensity, you’ll burn more sugar.
If you can become metabolically flexible and more efficient at burning fat (which you can achieve by adopting a low-carb diet and doing aerobic training), you’ll improve your ability to burn fat at higher intensities.
You’ll also conserve glycogen for the later stages of the race and become less reliant on exogenous sources of carbohydrates like gels and sports drinks, which can be hard to stomach when your body is under stress in a race.
This brings me back to the subject of carbo-loading. When you eat carbohydrates, especially the white and starchy ones, your blood sugar will spike. In response, your pancreas releases insulin to shuttle this sugar to the muscles and liver, where it will be stored as glycogen.
The problem is that like the hard drive on your iPhone or computer, your muscles and liver have limited storage capacity. Once full, you won’t be able to store any more and the excess will either have to be burnt immediately or stored as fat.
If you’re eating a standard Singaporean, Western or Indian diet, I argue that you’re already carbo-loaded. Eating additional carbohydrates in the days before your race adds no additional benefit, but it comes with the consequence of suppressing your ability to burn fat as the presence of insulin is known to turn off fat burning.
If you’re carrying excess body fat, crave sugary foods or are always hungry, have spiky energy levels throughout the day or hit the wall in training or races, you’re likely a poor fat burner.
By eating a diet that is lower in carbohydrates (especially the white and starchy ones) and higher in healthy fats, you’ll regulate insulin levels and will improve your ability to burn more fat.
With that, you’ll not only be able to run faster for longer; you’ll have better energy levels and will improve your body composition as excess fat starts to disappear.
If, by chance, you’re already eating a diet that is lower in carbohydrates and higher in healthy fats, kudos.
Adding back some high-quality carbohydrate in the form of fruits and vegetables such as kiwi and bananas or root vegetables like potato and parsnip, quinoa and dark chocolate during race week will help to “top up” those glycogen stores without compromising your fat-burning thanks to the metabolic hardware your body has earned through your dietary choices and low-intensity training.
That’s true carbo-loading!