Tuesday, May 17, 2011

Calorie Burning Basics

Most people know they need to increase calorie expenditure to reach their health and fitness goals.  At the same time, they have no clue how the body goes about doing it.  There are three ways the body burns calories:

1. Resting Metabolic Rate

You might hear resting metabolic rate (RMR) also referred to as basal metabolic rate or simply put, your metabolism.  This is the number of calories your body needs for its most vital functions.  In other words, if you stayed in bed all day not moving a muscle this is the amount it would take to keep your heart beating, lungs breathing, brain functioning, etc. 

RMR accounts for 60-70% of your daily calories.  That's far more than any other mechanism and it's important to note as we'll talk about down the road.

A number of factors determine your RMR:
  • Body composition - lean muscle mass is very active tissue therefore burns more calories
  • Age - metabolism decreases as we age
  • Sex - men typically have higher RMR's than women since they tend to have more muscle mass
  • Hormones - certain hormones, like those released when we are stressed, can have a negative impact
  • Medications - check with your doctor to see if anything you are taking as related side effects 

2. Physical Activity

Any bodily movement burns calories.  This includes planned exercise sessions, occupational and household work, recreational activities, etc.  Even twirling your hair, pacing back and forth, and shifting around in your desk chair counts (those types of movements are called NEAT: non-exercise activity thermogensis).  All movement burns calories so try to incorporate as much as you can in your daily routine.

Physical activity accounts for 15-30% of daily calorie expenditure.  Those who are more active will be closer to 30%.  Those take the elevator up one floor on a regular basis will be closer to the bottom end of the range. 

3. Thermic Effect of Food

It is very minimal but it must be said.  A measley 5-10% of our calories are burned through the process of food digestion.  Yes, it's true.  You can burn calories from eating so to speak.  Most of these foods are plain vegetables and fruits.  Don't bet on regularly eating meals that will result in a negative calorie balance.  And if you do, I bet you'll be hungry again in 30 minutes.

Take a close look at the above chart of an estimated daily calorie expenditure.  In upcoming posts I'll how to use the breakdown to your advantage and why things you may be doing just don't make sense.  Stay tuned...

No comments: