Weight Loss Tracker

Saturday, October 17, 2009

Cardio vs. Fat Burning modes -- good information to know

I've been thinking as I've been working out on the machines at the gym -- I've wondered what the benefits are of these two modes, cardio and fat burning.  I've found some differing opinions, but this was written by a doctor (found on a message board but credited to a Precor site) and explains how you may benefit from a lower-intensity workout (especially if you are, like me, trying to lose weight).  Here is the question that was asked and what she said:

Q. We have several workout machines in our office and I want to use them, but I'm confused about the different heart rate zones. What zone should I be training in to lose weight?

A. This is a great question that many people ask. It is important to realize that the body has two different fuels it converts to energy: carbohydrates and fats. The body burns these fuels in different proportions depending on your fitness and the intensity of your workout. Your body stores fewer carbohydrates than fat, yet it accesses the carbohydrates more easily. So the goal is to make your body more efficient at burning the stored fat while sparing the carbohydrates. Working out at higher heart rates [70 to 85 percent] will burn more carbohydrate calories in the short term, but it is working out in the lower zones [60 to 70 percent] that trains your body to become efficient at fat burning. In turn, this improves your endurance and aerobic fitness, eventually leading to a faster metabolic rate during exercise. This means that over time, you can burn as many calories at a low intensity as you were previously burning at a high intensity. With proper training this can happen in as little as three to six months.

Therefore, the best intensity for weight loss is one that seems 'fairly light' to 'somewhat hard'. Often people who cannot lose weight, or who even gain weight despite high intensity exercise and restrictive dieting, find success through a combination of slowing down their exercise, and improving the quality of their diet. This approach is not only more effective, but it's more fun and easier to stick to long-term!
-- Emily Cooper, M.D.

I sometimes tend to find it hard, actually, to keep my heart rate low enough to be in the fat-burning zone.  I think a lot of that has to do with the fact that I haven't exercised consistently or long enough for my heart to be strong enough to beat at a slower rate when exercise is introduced, but I have noticed in the past that it only takes a few weeks of moderate exercise about four times a week (or more) for my heart to respond accordingly.  I had times when I was younger and more fit that it was hard to get it up into the cardio zone.
So for a while now, I will work at getting and keeping myself in the fat-burning zone (since I have SO much to burn) and see how I feel about it.


  1. Great post! And great information. I wondered if I needed to push harder or what. I am an outdoor exersicer so I have to check my heart rate myself. I appreciate the information!

  2. The doctor is wrong. This is a common myth about exercising, but it's been disproven.

    If you work out at a higher intensity, your body may not burn as high as % of fat during the exercise, but it burns more calories. Then, at night when your body rebalances your fat stores, it burns the fat then. So your body is still "trained" to burn fat and you burn more calories and lose more weight overall.

    Plus there is no study that shows that working out a lower intensity trains your body over time to burn as much fat as working out at a high intensity.

    Also, the best way to make cardiac improvements is to do intervals... where you push hard and then back off and repeat several times. This will make you fitter and you can't do it if you are constantly holding back so you don't get out of your "fat burning" zone.

    Final, the formula 220-your age is not very accurate for determining your heart rate zones for the vast majority of people. In my case, that formula claims my maximum heart rate is 168. Well, I regularly was going as high as 173-177 when I ran and was no where near my maximum. So obviously my max was not 168. So, if I'd use the heart rate zone charts and tried to keep my heart rate into the "fat burning" zone, I would have been much too low. (According to my cardiac stress test, my max HR is 187.)

    You can google to find a number of ways to test for your maximum heart rate using exercise. If you are going to exercise according to heart rate zones, you owe it to yourself to find out what they really are so you don't short-change yourself by exercising at too high or too low a rate.

  3. Thanks, Mac. You know, since I posted this I've found a lot of countradictory information and was going to research more and post here when I found time (mid-term crunch time). I also didn't fully agree with what I was reading since I've been working out.

    I had also read that interval training was a good way to push the body as well. I was really thinking about it while I was working out yesterday on an elliptical at the gym. It was enough to make me want to re-think and re-research this.

    Thanks for your info, and I will use it to help me get this right. I want to know as much as others might want to.