Traditional sports nutrition research suggests athletes consume between 120-240 calories from carbohydrate per hour during exercise. However, research that came out a couple of years ago had some interesting conclusions which increased this range to up to 360 calories from carbohydrate per hour. When athletes got word of this, the buffet began and with that, accompanying GI issues did also.
If you follow the Fuel4mance blog or the work that I do surrounding metabolic efficiency, you know that it is possible to reduce the amount of calories from supplemental carbohydrates you eat if you teach your body to use more of its internal fat stores as energy at higher intensities. This is the cornerstone of metabolic efficiency.
However, this blog is not about what we already know. I want to introduce you to a concept I call "Calorie Intake Efficiency Ratio". Whenever I do metabolic efficiency testing, I peek inside of an athlete's body from a physiological standpoint to learn how their body uses their stored carbohydrate and fat throughout different intensities of exercise. Once I know this, I can accurately prescribe a nutrition plan to help improve metabolic efficiency. I can also give training parameters based on their current training cycle and physical training goals.
All of this is great but what athletes also want to know is how many calories they should eat during training. Enter the Calorie Intake Efficiency Ratio. This ratio is the relationship between the amount of calories that an athlete burns and the calories that they consume during a training session. I have collected data on athletes for many years regarding how many calories they burn (collected via power meters and heart rate monitors) and have found that most endurance athletes consume 10-35% of the total calories that they burn. I have also found a direct correlation between the risk of GI distress and a higher Calorie Intake Efficiency Ratio (read: eat more = more GI distress).
Thus, much of my work around metabolic efficiency has been on reducing the hourly calorie need in athletes so that nutrition does not become a limiter during racing and athletes do not overfeed themselves. When metabolic efficiency is properly developed, the Calorie Intake Efficiency Ratio is reduced to about 5-10%. This means that athletes only need to consume 5-10% of the total calories they burn to maintain energy levels. Of course, you must develop good metabolic efficiency first before you drastically reduce your hourly calorie intake.
Definitely something to keep in mind as the race season approaches. Your body doesn't need as many calories as you think it does as long as you train it to become more efficient. Why athletes strive to improve their physical efficiencies (swim, bike, run) and not pay attention to their nutrition efficiencies (metabolic) is puzzling but remember that you can develop metabolic efficiency in about 2-4 weeks so there is still time before race season hits.