Exercise and metabolism

23 January 2012

You’ve just finished a long day, made it though your Math and English classes, had soccer practice and are just getting ready to watch American Idol. You know that watching your favourite contestant belt it out on TV doesn’t take as much energy as your soccer drills, but just how much energy did your body need to complete all your daily activities anyway?

Metabolism is the term that describes the energy your body needs to get through a day of classes, sports and watching American Idol. Your Resting Metabolic Rate is the number of calories you burn to maintain life. Therefore if you are alive you have a resting metabolic rate. This accounts for 65-75% of all the energy you expend during the day and you can’t really affect this.

Did you know? Your metabolism allows the energy you take in from food to be used to keep your body moving and alive. You can change it by increasing the amount of exercise you do.

Is it true I can burn calories by eating food?

The thermic effect of eating is the energy your body uses to digest food. It takes energy to get energy out of the food you eat and this accounts for about 5-10% of the total calories you burn in a day. Finally there is your physical activity energy expenditure, which is the energy you use to do physical activities and which is the only aspect of your metabolism that you can change. You can significantly raise your metabolism just by fidgeting all day long! The more activity you do, the longer you do it (duration) and the harder you work (intensity) will all work to raise your metabolism.

Now here’s the big news - if during the course of the day you take in more calories than you burn, the extra calories will be stored in your body as fat. This was really useful in the caveman days when our ancestors would have gone for great lengths of time with little food; they could save the food they eat as fat to use later. These days however it is not so useful and is resulting in the obesity epidemic that we are experiencing right now in North America. The opposite is also true. If you burn more calories than you eat, your body will take those fat stores and use them for the energy you are not getting from food. There is no secret here, there is no other way around it, if you eat too much you will gain fat, if you want to lose fat you have to burn more calories than you take in.

Did you know? One pound of fat is 3500 calories, therefore to lose one pound of body weight you would have to burn 3500 calories more than what you eat.

Will the time of day I exercise make a difference to my metabolic rate?


Does the type of exercise I do make a difference?


Let me expand. Weight bearing aerobic exercise, like running, is best. This would include any sport where you would do any running. This type of exercise requires the greatest amount of energy because it takes a lot of work (and therefore increases your metabolism) to get oxygen to the muscle cells in your body. Weightlifting will burn calories as well but certainly not to the same extent as aerobic exercise. If you’re breathing hard you’re probably doing aerobic exercise. So the next time you’re watching American Idol, fidgeting as you wait for the results of who stays and who goes, remember it’s not just the contestants metabolism that’s working but yours too!

Did you know? You will continue to burn calories after you stop exercising for up to one hour if the exercise was of long duration and high intensity (for example running 12km in one hour). This can result in an extra 10-30 additional calories burned.

Learn More!

To calculate how many calories a day you would burn if you slept all day (Resting Metabolic Rate)

To figure out how many calories you are burning with the activities you are doing

Erin is a physiotherapist at CFB Petawawa, where she treats members of the Canadian Forces. She loves running and keeping her metabolism up!


This is content has that been provided for use on the CurioCity website.

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