Different Energy Sources and When to Use Them

by Tia Dewick in Nutrition

Every food product is made up of three different macronutrients (carbohydrates, fats and protein). Each of these macronutrients supply us with different energy roles and they need to be consumed at different times of the day for peak energy and recovery. Read below to see how each macronutrient influences your body.



There are predominantly two different types of carbohydrates which are fast releasing and slow releasing. Fast releasing carbohydrates include pasta and rice which typically fuels the body consistently for up to 4 hours. Whereas slow releasing carbohydrates include bread and sweets which will supply a rapid acceleration in energy supply which may only last up to an hour and so you will feel the need to snack more if you consume more fast releasing carbohydrates. Carbohydrates are needed to fuel high intensity workouts such as sprinting and so for optimal performance a large carbohydrate meal should be consumed 4 hours before a workout followed by a snack to top-up the energy stores around an 1 hour before your workout. Furthermore, ensure to consume carbohydrates post-workout to optimise your muscular recovery.

Do you ever feel those immense cravings late at night? That’s your body craving carbohydrates so try to make healthy choices by eating perhaps an apple or banana just to keep your body’s energy stores at the optimum. Then, overnight the liver carbohydrate stores will deplete and so consuming this slow releasing carbohydrates for breakfast ensures you have optimal energy for your day ahead!



Fat is the body’s most concentrated source of energy, providing more than twice as much potential energy than carbohydrates or protein. During exercise stored fat is broken down into fatty acids. These fatty acids are transported through the blood to muscles for fuel. Fat is also stored within muscle fibres, where it can be more easily accessed during exercise. Body fat is a virtually unlimited source of energy for athletes. Even those who are lean and mean have enough fat stored in muscle fibres and fat cells to supply up to 100,000 calories. 1 pound of stored fat provides approximately 3,600 calories of energy, and fat is essential for longer, slower, lower intensity and endurance exercise, such as cycling and walking.

Fat is slow to digest and can be converted into a usable form of energy. (this can take up to 6 hours to occur). After the body breaks down fat, it needs time to transport it to the working muscles before it can be used as energy. Converting stored body fat into energy takes a great deal of oxygen, so exercise intensity must decrease for this process to occur. For these reasons it’s not a good idea to eat foods high in fat immediately before or during intense exercise, as the workout will be done before the fat is available as usable energy.



Protein is the most important fuel to initiate muscular recovery. The body cannot store reserve protein stores and so in a perfect world we should consume some form of protein between 3-6 times a day. Consuming 40g of protein with your dinner does not offer the same recovery benefit of 20g every 3 hours.

How soon after your workout you need to consume protein depends on your frequency of training. If you train 2-3 times a week then consuming protein within the 24 hours following your workout will initiate muscular recovery. However, if you train 4-6 times a week, for optimal performance in your subsequent session, consuming protein within the first hour post-workout is preferable.