A nifty tool to plan your nutrition

I have been helping athletes to create nutrition plans for their races for a long time. For 25 years, I have worked with, listened to and learned from professional as well as recreational athletes. My advice was always based on evidence, studies that we and others conducted in the laboratory and in the field. Many athletes I worked with solved their nutrition issues like stomach problems, running out of energy by having a solid nutrition plan based on science.

I was always asking the same questions and would work out a plan depending on the answers. When Bill Braun, an athlete himself, contacted me a little while ago, we started to develop a web based tool for endurance athletes that helps to create a personalized and evidence based nutrition plan.

We called the tool CORE as we believe that nutrition is at the CORE of every performance and performance starts from this CORE. The tool is now available online on www.fuelthecore.com. This blog describes the basics of what CORE does and some of the science behind it.


Many endurance athletes don't get their nutrition right and therefore their races can be hit-and-miss. Often athletes quote nutrition as the main reason why a race did not go as planned? Why can’t they get it right? Maybe because there is so much information out there and so many opinions? Maybe because a plan that works for one person does not necessarily work for another? Nutrition is highly personal. Some athletes can tolerate anything, some athletes seem to get runners trots just from looking at gels! Some athletes sweat lots, some don't. Many factors will determine the requirements for a race including weather, temperature, humidity, of course the exercise intensity, the pace but also the availability of nutrition during a race and many other factors. There are a lot of things to consider. With CORE we tried to build a tool that takes all of this into account and for the athlete it will take the guesswork out of planning.

Under the bonnet

Without going into too much detail how the algorithms work, here are some of the factors that are taken into account:

Carbohydrate requirements

Carbohydrate requirements depend very much on the goal of training (or racing). If the goal is optimal performance, carbohydrate recommendations are generally higher. If training fat burning is a main goal, you want to minimise carbohydrate intake, so you don’t suppress fat burning. On the other hand, you don’t want the intensity of training to drop too much because that will mean, fewer calories burnt and less fat burnt! (these principles are discussed in this blog on periodised nutrition).

Fluid requirements

Sweat rate: there are individual differences and sweat rate is mostly influenced by the exercise intensity and environmental conditions. The amount of heat your body produces is determined by the power output. In other words, it is the pace that determines the heat production