Lessons on the Calorie-Burning Zone

From the Fat-Burning Zone to the Cardio-Zone—It’s All About the Calorie-Burning Zone
By Olivia Rossi, RN, MSN
Your Personal Trainer:

Do you have a “fat zone” you’d like to burn?  I do.  It’s located south of my waist and north of my knees.  Other common fat zones are known to reside between the shoulders and the elbows, from the chins to the shins, the chest to the hips, or any combination of the above!  Wouldn’t it be nice if we could get on a machine, dial in our own personal “fat zone” and say “Be gone”!!!

Unfortunately, it doesn’t work that way.  The best way to begin and to continue burning away your excess weight is to move.  Cardiovascular exercise, also known as aerobic exercise, will burn off your fat as well as provide you with long-lasting health benefits.  Excess calories, stored as fat, are shed slowly but surely when caloric intake is reduced and caloric output is increased.

What about those charts on treadmills, stationary bikes, stair steppers and other cardio-machines or posted on gym walls, charts listing heart rates for “fat-burning zones” or “cardio-zones?”  These can be confusing by misleading you into thinking that you are literally burning off your “fat zones” when you are working out in the “fat-burning zone.”  That is the zone of low intensity activity at which the body uses more fat as its source of fuel than it does at more moderate to higher exercise intensities where the body switches to the more efficient carbohydrate as fuel.  (See Women’s Report, “Exercise Intensity Defined,” October 13, 2009).  The important thing to remember is that, in both low and moderate intensity “zones” of exercise, your body is burning calories.  In its wisdom, it chooses the most efficient fuel to burn at the appropriate level of exercise.  Let me give you an example from exercise physiology.

Let’s say that you are working at a lower intensity, “fat-burning” level, walking at 2-miles per hour.  You will burn around 100 calories, with approximately 75 calories coming from burning fat as fuel. That’s 75%.  If you increase your intensity to a jog burning 200 calories, about 60% will be burned using fat as fuel but your body also uses a higher percentage of carbohydrate as fuel.  The percentage of fat used for fuel will be lower, approximately 60%, but a higher number of calories will be burned, 120 calories versus 75 calories as in the prior example.  Look at the big picture:  it takes 3500 calories to burn off one pound of body fat.  Covering a mile on foot at a moderate intensity burns around 100 calories.  That piece of cheesecake I ate last week was 300 calories!

There is a time and place for exercising in both zones.  Both promote fat loss and weight loss by burning calories.  The important point is that when you work at lower intensity levels, you have to go longer.  If you are just getting started on a fitness program as some of you might be as a part of your New Year’s resolutions, it’s good to start at lower intensities.  It is especially important if you have a lot of weight to lose and are not used to walking.  If you’re a veteran exerciser, it is also recommended that you alternate easier and harder days to avoid boredom, overuse or discouragement and, if weight loss is one of your goals, do it slowly.  One-to-two pounds a week has been shown to have long-term success in keeping weight off.   Think about losing five pounds at a time.  It’s less intimidating than telling yourself you have twenty pounds to lose.  You just have to lose five pounds and you get to practice doing it four times!

While it can get complicated, the message makes sense and it’s nothing new.  It’s really quite simple to understand but admittedly not always easy to do:  to lose weight you need to eat less and exercise more.  You lose weight and body fat when you burn more calories than you consume.  Eating less doesn’t mean starving yourself.  On the contrary, you need to supply your body and your muscles with the right fuel.  That includes carbohydrates–good, healthy, complex carbohydrates—whole grains, fresh fruits and vegetables and enough calories to have the energy to exercise.  Your body needs carbohydrates to burn fat.  It’s a matter of balance.  You also need balance in your exercise program.  While you are burning calories aerobically, you can help to add muscle by including two-to-three days of weight training per week, every other day.  There’s a bonus included:  if you have more muscle, you burn more calories both when you’re exercising and after you stop. Whether you burn those calories in the “fat-burning zone” or the “cardio-zone,” the most important thing is that you burn them!  Move into the “calorie- burning zone!”

Yours in fitness,
Olivia Rossi, RN, MSN
Certified Clinical Exercise Specialist, ACSM
Certified Personal Trainer, ACSM

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