Food and energy

A common statement is that an individual cannot “out-train” a bad diet. This is a good philosophy for players to adopt. While a player may be engaged in a comprehensive training programme, they are unlikely to achieve optimum training adaptation unless their nutritional regime is also tailored towards their goals. When it comes to nutrition, there is no one-size-fits-all solution. A highly personalised approach is a must. This is because nutritional requirements are dependent on so many individual variables. For example, the energy consumption of a 120kg prop is going to be very different to that of a 90kg fullback. Not only will their body measurements affect their nutrition needs, but so will their roles on the pitch.

Figure 15. Sound nutritional practices are a cornerstone of optimal performance.


The energy content of food is measured in units called calories or kcal. Energy from food can be categorised under three main groups, collectively known as macronutrients. The three energy-providing macronutrients are carbohydrates, protein, and fat. To understand macronutrients, it is important to know how much energy each provides. The energy content per gram of each macronutrient is displayed on the Table 2. below.

Table 2. Energy content of nutrients

Carbohydrate 4 Kcal per 1g
Protein 4 Kcal per 1g
Fat 9 Kcal per 1g

A player’s body weight is generally determined by one underlying principle, thermodynamics. This concerns calories in versus calories out. In other words, a player’s bodyweight depends on the difference between the energy they consume and the energy they expend. There are three scenarios when it comes to weight management, and each can be summarised using a simple equation:

  • Weight gain occurs when a player consumes more energy than they expend, i.e. calories in are greater than calories out.
  • Weight loss occurs when a player consumes less energy than they expend, i.e. calories in are less than calories out.
  • Weight maintenance occurs when a player consumes as much energy as they expend, i.e. calories in = calories out.

Table 3. below outlines the process further.

Table 3. Energy Balance

Energy In

Energy Out

Food and drink (i.e. carbohydrates, protein, and fat)

Bodily Functions (i.e. organ function such as breathing)


Breakdown of food


Physical activity



Carbohydrates convert to glucose (blood sugars) once digested. The main functions of carbohydrates are to supply energy to the working muscle, store energy within the muscle, maintain intestinal functionality and to spare protein and fat. They also are the bodies main source of fuel for exercise. Carbohydrates can be broken down into two groups: complex carbohydrates and simple carbohydrates.

  • Complex carbohydrates take longer to break down in the body, allowing for a slow and steady release of sugar. This slow release makes us feel satiated and full for long periods. Ideally, complex carbohydrates should account for most of a player’s daily carbohydrate intake. As well as keeping us fuller for longer, they are nutrient-dense and help to stabilise blood sugar levels. Examples of complex carbohydrates include wholegrains and legumes.


  • Simple carbohydrates are broken down much more easily, and sugars are therefore released into the body more rapidly. While these foods are often demonised, they have their benefits if consumed at the right time and in moderation. For example, the fast-releasing structure of simple carbohydrates make for a great pre and post training snack. The resulting energy boost can fuel bursts of activity and aid recovery. Examples of simple carbohydrates are sugary foods, as well as refined grains such as white rice and white bread.


Protein and fats

Every cell in our body is made of proteins. They play an essential role in every biological process. Without them, our bodies cannot function.  While protein does provide energy (4kcal per gram), it is used differently to carbohydrates and fat. The protein consumed is mainly used to build and maintain muscle tissue. The muscle growth process is as follows:

  1. Physical activity causes microfibril tears in the muscle
  2. Protein is used to repair these tears in the muscle
  3. The repair process causes the muscle to grow in mass. This is the body’s defence mechanism against future tears.

The microscopic muscle tears cause no harm to the body. By consuming protein directly after exercising, the player is helping muscles to recover, repair and grow. The roles of protein in the body are as follows:

  • Building block for bone, muscle, cartilage, skin, and blood structure
  • Production of enzymes, hormones, and other body chemicals
  • Under extreme circumstances (such as starvation), it may be used as an energy source.

Of all the macronutrients, fat is commonly perceived as the least healthy. This, however, is a myth. Fats, also known as lipids, are essential for our health. Its negative reputation is likely due to its higher energy content (9kcal per gram). Therefore, people often associate the consumption of lipids with health problems such as obesity and diabetes. The truth is that over-consumption of any macronutrient will be detrimental to one’s health, so moderation is the golden rule. Fat sources from food include oily fish, nuts, seeds, avocados, cheese, butter, and oils. Functions of lipids in the body include acting as an energy source, cell structure, hormone production as well as development and function of cerebral and nerve tissue.


Recommended daily intakes

Table 4. RDA


45-65% of overall calories (this may vary depending on energy requirements, e.g. strenuous activity will necessitate increased carbohydrate consumption)


10-35% of overall calories (this will also depend on energy consumption, e.g. an intense resistance training session will require higher protein intake for optimum recovery)


20-35% of overall calories (this is dependent on protein and carbohydrate intake, but should generally be approximately 30%)

Micronutrients are essential nutrients which regulate and trigger a range of bodily functions. They include nutrients such as minerals (e.g. sodium, potassium, calcium, zinc copper etc.) vitamins (e.g. vitamins A, B, C, D, E, K) and water. They play a key role in the breakdown of food and during strenuous physical activity. When a player meets their daily recommended intake of various micronutrients, it helps the body to function at maximum capacity. Nutrient-dense (nutritious) foods, are those which are rich in micronutrients. Energy-dense foods (sometimes referred to as empty calories) are those which are high in calories, but not necessarily micronutrients. While it is possible to meet one’s macronutrient targets through the consumption of energy-dense foods alone, it is favourable to opt for nutrient-dense food where possible. Otherwise, one may be at risk of developing micronutrient deficiencies which can have negative health implications, potentially impacting athletic performance.


Guidelines for energy intake

In general, there are three stages where the player can ensure that their energy stores are well stocked. These can be categorised as pre, during, and post-training/competition. Ivy in 2004, developed the term of “Nutrient Timing” that is now well established in sport and exercise nutrition. Nutrient Timing refers to the ingestion of appropriate nutrients and energy before, during and after exercise. Here we consider how the player may ensure good nutrient timing with the goal of having energy stores stocked before training, supplementing energy availability and stores during exercise and competition and restocking energy stores after training and competition.

  • Pre-exercise. In addition to ensuring a balanced energy intake through any given day with breakfast, lunch and an evening meal, during the immediate hours prior to training or competition the player can ensure that energy stores are well-stocked by ingesting a light pre-training/competition meal. See Table 5. for some examples.
  • During exercise. Nutrient supplementation immediately before and every 15-20 minutes during exercise which lasts more than one hour may improve performance and enhance recovery (Ivy 2004). Thus, general recommendations from Burke in 2011, include ingesting between 30g and 60g of a carbohydrate per hour. This can be conveniently accomplished through regular ingestion (every 10 to 15 minutes) of easily digested carbohydrate drinks or through eating easily digested carbohydrate foods such as a banana if the player finds solid food tolerable and also drinking 250 mls of water every 10-15 minutes to ensure adequate hydration. Small amount of protein within the beverage or food may enhance the exercise and recovery outcome. See Table 5.
  • Post-exercise. The period immediately after the exercise bout or training session is also known as the anabolic phase. During this phase, the body is in an optimum state to enhance growth and positive adaptations if the right stimuli are present. Muscle cells are in their optimum state of accepting and storing energy during the 45-minute post-exercise period. Ensuring that the player eats a mixed meal containing carbohydrate, fat and protein as soon as possible post-exercise is good practice. The meal can include readily available carbohydrate foods such as bread, pasta, potatoes as well as a protein-based food such as pulses (beans), fish or meat, and a variety of vegetables and some fruits. While many players may use supplemental meal replacements please note that any supplements must be screened and vetted for contamination, which is a very real concern in sports nutrition. See Table 5.



Given the non-specialist education background of the strength and conditioning coach in nutrition, the strength and conditioning coach’s role and responsibility must be clearly defined in that they may not be regarded as an expert in this area. In a situation where a sports nutritionist is not readily available the strength and conditioning coach may be called upon to fulfil a most important role in giving basic nutritional advice to the players.

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Table 5. Nutrient timing guidelines

Nutrient Timing

Suggestions for snacks and meals


Light meals containing the macronutrients are ideal approximately two hours to 45 minutes pre-exercise e.g. oat-based cereals with added fruit such as bananas or grilled chicken, broccoli, and sweet potato.

Always ensure to continue drinking 250 mls of water every 15 minutes during the 2 hours before exercise.

During exercise

Lightly diluted carbohydrate drinks with added protein or easily digested solid foods such as a banana and water are ideal at intervals during exercise. During competition, ingesting water during play as frequently as possible and the additional intake of lightly diluted carbohydrate drinks at half time is recommended.


The post exercise meal should be a large one if the player can tolerate this. If not, a small meal with a balance of fat, protein and carbohydrates is important and can be obtained from a selection from:

Water: 500mls to 1 litre

Carbohydrates: potatoes, bread, pasta.

Protein: meat, fish, poultry, eggs, vegetarian sources include pulses such as beans, peas, lentils.

The addition of vegetables and fruits is important as key micronutrients will then be assured.