Martin MacDonald: “Nutrition for triathletes is uniquely complex”

Sports nutrition expert shares his thoughts on fuelling up for multisport


Martin MacDonald
In this Q&A, clinical sports nutritionist Martin MacDonald discusses the unique intake needs of triathletes, his recommendations for beginners, and triathletes’ most common nutritional mistakes.


Martin will be speaking at The Triathlon Show 2014, taking place at Sandown Park, Surrey on 28 February to 2 March. For more information head to

How do a triathlete’s nutritional needs differ from those of other endurance athletes?

Nutrition for triathletes is uniquely complex because of the necessity to fuel for and during the three disciplines. The necessity to be both powerful as well as aerobically and anaerobically ‘fit’ makes the habitual diet for a triathlete all the more important. This means choosing the right diet is very important if you are to maximise your potential.  

What would you recommend to beginners looking to optimise their diet?

The most important factor with regards to performance nutrition is energy intake. Before looking at carbohydrates, proteins and fats it is important to simply get enough total energy to train and perform well. 

How does this picture change when an athlete decides to go long?

With an increasing distance comes a relative reduction in the intensity of the exercise, which is where the idea of fat adaptation may come into its own. Through increases in dietary fat intake and practices such as training with low glycogen it may enhance an individual’s performance. 

What is the most common nutritional mistake triathletes make?

The two most common mistakes are firstly not eating sufficient energy due to the belief that ‘eating more will make me gain weight’, and secondly extreme practices such as chronically very low carbohydrate/fat intakes in the belief that this way of eating will enhance performance over a more moderate approach.

How can intermittent fasting, low carbohydrate and paleo benefit triathletes?

Each of these practices, either singularly or in conjunction with one another, may have unique benefits with regards to either triathlon performance or body composition. Unfortunately, taken as a blanket approach they can be sub-optimal. 


Therefore it is important, if you wish to try these methodologies, to know when and how to use them and perhaps more importantly, when to steer clear – which is what I will be discussing at the Triathlon Show this year.