Marion Freijsen A blog about Sports, Fitness & Health

Energy – where do you get yours from??

I love this topic, but it is one of the hardest to tackle in a simple blog. If you want to achieve anything with your exercise or sport though, or simply want to maintain a healthy balance in life, you need to understand how your body is fuelled.

Let me break it down to basics – there’s three major sources of energy that your body can use: carbohydrates, protein and fat. All day long, these sources are broken down into usable format by your body, which is effectively just one big generator when it comes to food.

Carbohydrate is stored in a different form (called glycogen) in your muscles and liver, but only a limited supply is held there. For most, enough for about 90 mins. of exercise at a hard pace.

Fat unfortunately has been given such a negative image, but is an essential protector of your internal organs. You can’t do without it!

Protein is basically the stuff that is the foundation of your muscles and your muscles need it to grow and stay healthy.

Now for the complex part. Each is broken down in a different way by your body. The available source of carbs in your muscles/liver is very easy to grab and burn when needed, fat takes a lot longer to break down and protein is the hardest to use.
When you exercise, your body needs to continually break down energy sources to generate the extra fuel you need, and it will choose automatically whatever is most appropriate and easiest to use for the level of intensity you choose to work out at.

It’s not like you have the three sources in little individual pots though that are emptied one after the other, it’s more of a blend of the three at any one time. But the blend will vary according to your needs at the time. If you work out hard, you will depend mostly on that small source of readily available carbs I mentioned. Then once that source is running out, your body will start to up the use of the others. However, to keep up with you whilst you are pushing yourself to your limit, your body will have to work harder as it now has to convert more fat and/or protein which takes longer to accomplish. This is why, apart from you simply running out of air ofcourse,  you slow down as you get more tired, and eventually hit that infamous “Wall”. It’s simply your body saying, “Stop I can’t keep up with you any longer!! Give me a break!!”

Given that you only can exercise at a high pace for around 90 mins. using carbohydrates, but you burn very little fat at that time, you can perhaps understand why you need to consider HOW hard you exercise based on what you want to achieve. If you really want to lose fat, you don’t want to be working out that hard, because your body will not use fat necessarily as their main source of fuel but the easiest it can find: carbs. Burning fat therefore also requires you to work out over a longer period of time…again, if you work out at a lower pace, you will burn a mixture of fat and carbs, but to burn mostly fat, you need a continued effort in order to make sure you don’t just use the carbs after all. Another way of achieving that your body grabs more fats then carbs is to do spurts of effort at a high pace which will mean you will use carbs then, and will then switch to more fats in the lower intensity intervals.

Then a final word on protein – using this is not good news. If you work-out for a long period of time without adding new food to your system which can be broken down for fuel – your body will ultimately have to switch to burning protein. And what is the source of protein? Yes, right, your muscles. So whilst you think you are working out so hard that you are getting to point of exhaustion and therefore it HAS to be burning up all that stuff you don’t want, you are actually getting to a stage where you are burning up those muscles that you are hoping to build up! So make sure you do eat enough carbohydrates, particularly before a work-out to ensure your muscles have a store ready for use. And don’t forget to replenish it when you are done!!! If you did deplete your entire store of glycogen (in muscles/liver) then it will take a good 24 hours for your body to refill that store. So pace your work-outs over time as well as the intensity of each workout individually.

Wow – and this is meant to be the simple version!! It is obviously not intended to give a total overview of all the processes that take place to generate energy which is even more complex. But I hope you enjoy just understanding a little bit better what happens when you work-out and how to choose a work-out to accomplish your own goals! Let me know if you have questions… I’ll make sure I answer them in a future blog.