Sports nutrition – the basics

Nutrition for athletes is a huge topic. Entire books can be (and have been) written on the subject. It can be an extremely complicated, in depth subject, causing much confusion for many people. What should I eat? How much should I eat? How often should I eat? When should I eat certain types of food? It can all get a bit too much really!

As amateur athletes, we often don’t have easy, ready access to coaches and dieticians who can provide us with a food plan; so having a basic understanding of our own nutritional requirements is rather important. Being able to think about what you are eating, to ensure you are giving your body what it needs, will keep you fit and healthy. Get the basics right and you will be performing at your best!

Typically, adults burn around 2,000 to 2,500 calories. This of course varies based on your age, weight and metabolism, as well as a few other factors. But during exercise, you burn energy at a higher rate. Depending on how intense your activity levels are, you can burn anywhere between an additional 100 to 1,000 calories an hour! Knowing what types of food to eat, and when, is important to keep you going strong.


Carbohydrates are complex structures in foods that are broken down by your body, to provide energy. Not just energy for exercise, but energy for the basic functions of your body. Effectively, carbohydrates are the fuel which keep you going. Carbohydrates can be classified by their Glycaemic Index (GI), and what types you eat will depend on your type of exercise.


Low GI carbohydrates are slowly broken down by your body, to provide longer, sustained energy. Typically, these types of carbohydrates are used before and after exercise, to fuel your activities and top up your body’s energy stores. Good sources of low GI foods include whole fruits such as bananas and oranges, wholegrain breads and cereals, baked beans and whole wheat pasta.

High GI carbohydrates are quickly broken down by your body to provide you with a quick hit of energy. These types of carbohydrates are good for topping up and providing you with ongoing energy during sports, as well as a quick way of providing energy after exercise to once again help replace the energy you have used from your energy stores. Foods such as white bread, white rice, sports drinks and pretty much every lolly you will find on the supermarket shelves are all fairly high GI carbohydrate sources.


Proteins are complex structures, made up of amino acids. Proteins are the building blocks of your body’s structural components, including your muscles. Proteins are also required for the cells in your body to actually function properly.

During exercise, some of the energy you use comes from proteins. In addition, some muscle tissue is broken down and used as an energy source (this is known as catabolism). So its important to get enough protein in your regular diet, as well as giving yourself a top up after exercise to allow your muscles to recover from your efforts properly.


Good sources of protein typically include lean cuts of meat, particularly chicken and fish; low fat dairy products; and the humble egg!


Keeping yourself adequately hydrated is extremely important to your performance during sports. Let your fluid levels drop, and so will your performance.

Typically, the old rule of 6 to 8 glasses of water on a daily basis is adequate to keep you hydrated without any regular physical activity. During exercise, you will need to be drinking a bit more though. A good guide is to try and drink about 150-200ml of water for every 15-20 minutes of activity; but this rate obviously varies depending on exercise intensity, metabolism, age, weight, temperature and a few other factors. On hot days, it is easy to sweat at a rate of more than 1 litre per hour!

When you sweat too much without replacing your fluids, you will begin to see a decline in your abilities. A drop of 2% of your body weight, as a result of fluid loss, will see performance drops. At a 5% loss, these performance drops will be quite significant. With a loss of body weight between 6% and 10% as a result of fluid loss, you will see a complete loss of your ability to perform. In addition, you will be at risk of heat stroke and even death…..not the best situation to be in! So make sure you keep your fluid levels up when you are out there exercising!

Its also important to remember that when you sweat, you lose more than just water. For shorter, less intense forms of exercise, plain water is usually fine for hydration. But for endurance sports, you are better off drinking something with some added electrolytes.


Before exercise……

Before exercise, you should focus on low GI carbohydrate foods. They are vital in building up your energy levels to allow you to head out and exercise. Its important to make sure you finish consuming these foods at least an hour before you are active, as this allows the body to actually begin to break down and absorb the carbohydrates into your blood stream, where they can be used to fuel your sports. Also remember to drink up, to make sure your body isn’t going into any form of physical activity under an already slightly dehydrated.

During exercise…..

For non-endurance sports and activities, typically lasting less than 1 hour, you usually don’t need to eat much (if anything at all!!). The energy you have consumed from the low GI foods, in addition to your body’s natural energy stores, will be more than enough to last for an hour of exercising. Be sure to top up your fluids though, you will still benefit from this.

For the endurance sports, take some food with you. This would normally be high GI food, which will allow you to top up your energy levels quickly and to keep you performing. Eat small amounts, on a regular basis. If you don’t eat enough, your energy stores will drop quite low, which results in a drop in your blood sugar….resulting in no energy to actually perform at all! Remember to keep drinking on a regular basis. Around 150-200ml every 15 or 20 minutes is a good guide, but this can vary depending on your level of intensity, temperatures and other factors.

After exercise……

Eat quickly. Getting food into your system within 30 minutes of finishing physical activity will help to maximise your recovery, and help your body to re-fuel. Proteins are important to help rebuild muscles. A combination of both low and high GI carbohydrates are required, so your body can begin to quickly replenish its energy stores, as well as provide you with energy for the rest of the day. After exercise, your metabolism can be a bit higher for the next 24 hours, so make sure you don’t starve yourself!  Be sure to keep drinking too… need to make sure you top up any fluids you may have lost during exercise, and make sure your body is adequately hydrated for the next time you are active. Water is good, but something with a bit of additional electrolytes is better, especially if you have been sweating a lot during exercise.

Wearing a heart rate monitor during exercise is also a good idea, as it can give you an idea as to how much energy you have burned. This can give you a bit of a guide as to how much extra you might need to be eating as a result of your sporting endeavours.


Remember the food pyramid that your teachers showed you in school? Well, that’s what you should be eating!


On top of your carbohydrate and protein rich foods, you need to be eating a range of fruits and veggies for vitamins and minerals; as well as healthy fats and oils to keep your body functioning properly. Not from fast foods where the oils drip down your fingers, but from good sources such as olive oil, nuts and dairy products.  Eating a healthy, balanced diet is the key to maintaining a healthy body, so you can get out there, be active and be at your best!


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