Nutrition in football

The metabolic rate is often referred to as the bodies energy expenditure and consists of three large components:

• Basal metabolic rate (BMR): this is the amount of energy needed to keep your body – even in full rest – functioning. It is a large part of your total expenditure.
• Thermogenesis: it is the amount of energy your body needs to digest the food as well as transport and store the nutrients.
• Energy used during physical activity.

Basal metabolism is influenced by a number of factors such as body composition – especially fat-free mass - and size, age, growth, genetics, gender, hormones, environmental temperature, drugs and dietary deficiencies (M. Bubbs, 2019). Given the number of influencing factors, it seems odd that basal metabolic rate could be captured with a formula. Yet, the Harris Benedict equation is widely used for many years. Similarly, it shouldn't come as a surprise that the equation has been reviewed and found inaccurate in a clinical setting on several occasions (Pavlidou et al., 2023; Bendavid et al., 2021). Calorimetry (both direct and indirect) are often cited as the gold standard in resting energy expenditure. But even these methods have some limitations (Honore, 2021). Yet from a practical point of view, how many S&C coaches within football would be able to have BMR calculated by calorimetry for a full squad?

Finally, a correct calculation of energy requirements for physical activity can also have its challenges. Often the use of standardized physical activity levels (PALs) is suggested, even in sports nutrition guides (Bean, 2017). A first problem is that self-report on overall physical activity seems to be unreliable to moderate at best (Prince et al., 2008; Scott et al., 2012). Secondly, within football the intensity levels across different sessions are varying depending on the goal. A competitive match will have the biggest intensity, while a tactical session or a technical / recovery session will be much less intense. With a lower intensity, comes a lower energy demand. External demands are easily available today as Global Positioning Systems (GPS) devices are more and more common in today's game. Even at a lower level. But the same external load can give a huge difference between individuals on an internal level. So, it might well be that two players who participate in the same session have very different energy requirements. The problem with mapping internal load is that simple heart rate monitoring might not be enough. These days, biomarkers are seen as the way forward (Haller, 2023). The practical application of this method however as well as the budgetary requirements mean that this is only done at top-level. Continuous glucose monitoring (CGM) might be an answer to that problem, but for now it is mostly used in endurance sports (Flockhart & Larsen, 2024; Bauhaus et al., 2023). The many contacts between players during games are probably one of the factors why it has not been introduced in football. All this should make it quite clear that it is very difficult for an S&C coach to provide his athlete with a valid estimate of the total daily energy expenditure (TDEE), which is the amount of fuel the player needs to support his training and lead to the required training adaptations.

While CHO have a clear role in performance within football, recent research also seems to suggest sufficient CHO availability has a role in recovery as glycogen seems to have a role as a regulator in signalling response influencing mitochondrial biogenesis and oxidative metabolism (Tavares et al., 2023). Both the required quantity of CHO as the influence on recovery show that periodisation and timing will be an important aspect of an athlete’s nutritional strategies. More on that later in this article.

While fat often has a negative image, they are as much an essential part of the daily diet as CHO and protein. As an energy source, they are less important within football, although they still are an energy source in the recovery period between high-intensity bouts. (Maclaren & Morton, 2012) A distinction should be made by healthy and unhealthy fats. The availability of health fatty acids has shown to have a positive effect on post-exercise resynthesis of glycogen within the skeletal muscles (Lundsgaard et al., 2020).

The importance of meal timing and nutritional periodisation was already highlighted before. The research of Anderson et al. (2017) is often cited as evidence of this practice at the highest-level. Dr. Tom Little developed the colour fit method to support players to make the correct food choices. His method uses three icons: a yellow heart for health-related nutrition, a green runner for performance nutrition and a red muscular torso for food that supports lean mass. His method is widely used by English league teams such as Arsenal, Manchester city and Chelsea. The beauty of this system is that it takes the complexity of nutrition down to a very ‘digestible’ level for the player. But while this method supports food choices, the athlete might still need support with overall timing of meals as well as portion sizes and total energy uptake (Bonnici et al., 2019). While CHO needs to be planned around training and matches – the more exercise intense period of the day – a good overall distribution of protein intake over the day needs to be provided. Research suggests four to five meals with a protein intake of 0.4 g.kg^-1 per meal.

Icons used by Dr. Tom Little in his colour-fit method used by o.a. Arsenal, Chelsea and Manchester City

While this article might help S&C coaches to support their players, it should be clear that nutrition is a complex matter which is best tackled by a sports nutritionist given the various influencing factors mentioned at the start of the article. Especially with regards to special populations such as injured athletes or youngsters, more specific guidelines are to be considered which are not really part of the scope of this article. Other aspects which have not been included but should be looked at in more detail to fully support performance and recovery are hydration, the need for wholesome food and supplements. The food pyramid for athletes gives a more general overview of all aspects of nutrition for the player. S&C coaches are advised to work through the different tiers when implementing new food strategies. 

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