Adequate nutrition is required for any athlete who wishes to perform better. 
In this article we shall cover the following areas:
• What are essential nutrients?
• Food sources
• Intake ratio
What are Essential nutrients?
The essential nutrients are required by your body to function and grow properly which it cannot produce by itself, or in large enough quantities. 
Therefore, you must get them through eating and drinking. You may have already heard of macro and micronutrients, but you may not really know what these terms mean.
Here’s the meaning in simple terms:
• Macronutrients are foods consumed in large amounts such as proteins and carbohydrates. You may have heard of people talking or logging their ‘macros’. This refers to how many carbs, proteins, and fats they’re going to eat.
• Micronutrients are vitamins and minerals that are found in foods, however, the amounts needed are very small but are no less important.
Let’s look into macronutrients a little deeper.
The Essential Macronutrients
These are the big ones that you will consume everyday likely without even thinking about it.
We’re talking about proteins, carbohydrates and fats.
You could say that protein is the buzz word of health and fitness. We are told to eat more protein to build strong muscle.
But what does it do?
The British Nutrition Foundation outlines that protein is within all cells and tissues in the body and is likened to the bricks and mortar of our structure. It helps with growth and repair, protein also provides a bit of energy, although it isn’t our main energy source. 
Behind water, protein is the second biggest compound, it is mostly present in muscle, skin and within your blood.
Clearly, protein is a big deal, and you should consume about 0.75g per kilogram of bodyweight as a minimum although athletes should consider 1.2-2g per kilogram.
After a bout of high intensity exercise a milk-based protein source is very effective to repair muscle damage.
Whereas protein may contribute to around 20% of our energy intake, carbohydrates are the main fuel to keep your fire burning.
In fact, carbohydrates don’t just keep your muscles energised for exercise, it is the main fuel for brain function; the brain cannot produce it nor store it, so you need to feed it. 
There’s a lot of misunderstanding about carbohydrates and that they are bad for you.
Many people try to avoid them to lose weight. However, you will only start gaining fat when you eat too many for the activity that you do.
When you eat carbohydrates, they are broken down and then they are converted by the body into glucose. This is then used immediately by the body for fuel or it is stored in the muscles and liver as glycogen for activity later down the line.
It is worth considering that if you eat lots of carbohydrates, but it’s not immediately used to fuel activity it will be stored for your next bout of exercise.
However, if you do not perform much exercise but keep consuming high carb food sources the muscles and liver will already be full and the excess will be stored as fat.
If you are active, and you are involved in lots of sports and exercise there is a clear benefit of carbohydrate consumption to improve sports performance. This has been identified from as early as the 1930s. 
For your information, when your glycogen stores are full, it can fuel around 90-120 minutes of intense exercise.  A rugby game is less than this, so ensure that you fuel up before a game.
A good guide is to consume 6-10g of carbohydrate per kilogram of bodyweight for 1-3 hours of moderate to high intensity exercise such as a game of rugby.
Again, fats are potentially misunderstood.
Most people avoid fats like the plague; however, your body needs them to absorb certain vitamins such as D, A, E and K. 
While you need to keep an eye on how much fat you do consume, it is understanding what is classed as good or bad fat.
Let’s start with the more obvious.
• Bad Fats – fried foods and junk foods contain large amounts of saturated fat. This can include bacon, sausages, biscuits, salami, crisps, chips, burgers, and chocolates. It’s all of the typical foods that we generally know are bad for you. They maybe considered treats. 
• Good Fats – on the other hand are called monounsaturated and polyunsaturated fats that are found in whole eggs, avocados, nuts, fish, olive oil, and seeds. 
Fats are a source of energy; they help with cell growth as well as playing a role in your hormones whilst protecting organs and keeping you warm.
Because fats contain so much energy, we need to eat less of them compared to proteins and carbs.
Why are bad fats bad and good fats good?
Too much saturated fats builds up cholesterol in your arteries and blood vessels. It lines the walls, makes them less flexible and constricts blood flow. This makes your heart work harder and can lead to heart disease, strokes, and potential death. This cholesterol is known as LDL – the bad cholesterol.
Like fats, there’s also good cholesterol.
Good cholesterol known as HDL clears the arteries of bad cholesterol and takes it back to the liver which then removes it. It is consuming the good fats that raise HDL levels. 
Let’s not forget water. Being dehydrated can lead to a loss of performance, in severe cases it can lead to kidney damage and (painful) kidney stones. 
Water also plays an important part in the role of nutrition for cognitive function.
We have already written an article about hydration and sports performance, here. This will outline how to calculate your sweat rate to maximise your output.
In a climate like the UK, you should aim for about 1.2 litres daily, but adjust this depending on activity levels and heat.
Bear in mind that your body can survive a considerably longer time without food than it can without water, so do not neglect fluid intake. 
We must also say that it is advised to minimise alcohol consumption after sport.
Consumption of alcohol in large amounts post competition or training can negatively effect blood flow, muscle recovery, rehydration, and the replacement of glycogen stores. 
What do these macronutrients look like?
Okay, so many foods will contain a combination of protein, carbohydrates, and fats.
Let’s take a typical fast-food burger. It will have high levels of all three.
You may think that this is great, but really, we need to look at the sources of the macronutrients we eat, not just because something is high in protein that it is good for you.
Here’s a simple breakdown.
• Grilled chicken breast
• Grilled salmon
• Grilled rump steak
• Low fat milk
• Baked beans
• Jacket potato
• Wholemeal bread
• Wholewheat pasta
• Nut butter spreads
• Oily fish such as mackerel or sardines
• Sunflower seeds
• Olive oil
• Rapeseed oil
• Sesame seeds
Try to avoid
• White breads and pasta
• Processed meats including sausages, burgers, cured meats
• Deep fried foods such as KFC chicken, mozzarella sticks, onion rings, doughnuts, hash browns
• High sugar fizzy drinks
• Sweets, crisps, milk chocolate
According to the Dietary Reference Values for Food Energy and Nutrients in the United Kingdom these are the ratios for a typical adult for each macronutrient of total energy intake (not including water).
Don’t forget your 1.2 litres of fluid daily!
Don’t skip on carbohydrates, your body and brain need them for fuel. Remember that you should adjust your intake dependant on activity. If you are training for 1 hour per day, ensure you’re getting 6-10g per kg of body weight, if you’re not training as often reduce this.
If you’re training in the gym and playing rugby you should aim for around 2g per kg of bodyweight for your protein intake. Try to vary your intake of proteins so include beans, pulses, grilled lean cuts of meat and low-fat milk products.
Fats are not always the devil. Avoid fats that are often used to fry foods or found in treat style foods like biscuits, milk chocolate and processed meats. Instead opt for olives, avocados, nuts, and oily fish.
Always consider fluid intake, and not just when you’re in the gym or on the field. Just 2% of dehydration reduces mental and physical performance. 
These are the personal views of Ben Bunting, a former player at Chesterfield Panthers and currently studying a Postgraduate in Sports Exercise and Nutrition at Leeds Beckett Carnegie School of Sport (Leeds Beckett Carnegie School of Sport).