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Cardio....The Fat Burning Zone (sigh).

I have a few announcements before I get to today's Q&A.....

1) Thanks to everyone who is still reading and sending me questions and feedback! I totally appreciate the support and the interest you all have shown.

2) Anyone want to go grocery shopping with me? If you do, I am hosting a FREE shopping tour at the Whole Foods Market in Scottsdale, AZ on wed. march 21st at 7pm. If you or anyone you know who is out here and wants to come out please let me know. It is going to be a good time. We are going to go through the store and learn how to read food labels and make some healthy choices. As well as learn a little bit about what we ARE eating and what we SHOULD be eating.

Okay, onto todays Q&A. I had a few questions about cardio as of late so I thought I would entertain this one about the fat burning zone since it seems like people are a little misunderstood about the information that is being posted on their treadmill, elliptical machine or bicycle.

When I do cardio, I try and work in the "fat burning zone" that is listed on the treadmill. Sometimes my heart rate goes higher than this. Does that mean that I am not burning fat?

Truth be told, the "fat burning zone" on the cardio equipment never made much sense to me from a training perspective. What the fat burning zone really tells us that at a lower work rate (lower intensity), we are burning a higher percentage of our calories from fat. On paper, that sounds like a great thing! The only problem with it is that at that lower work rate, we aren't burning that many calories to begin with. Whether the calories are coming from fat storage or not is a moot point. Technically, we burn the most percentage of fat when we are at rest. So, if you want to burn only fat, just take a nap! But again, how many calories are you really burning overal when you are sitting and lounging around the house? Not much!

Okay, so where am I going with all this? Really, what we want to look at is total
caloric expenditure. Significant research points to the fact that at the end of the day, the most imporant thing is caloric expenditure. Ask yourself, "Have you created a caloric deficit?" "Have you burned more than you take in?"

When we get into the gym and actually push ourselves hard, we burn more calories. When we push ourselves REALLY hard, we begin to go anaerobic. This happens around 80% of your Vo2max (the maximal amount of oxygen your body can take in and use efficiently). When we go anaerobic, there is a shift in metabolism from fat oxidation towards glucose oxidation (gluces is blood sugar, and glycogen is the stored form of glucose). While this may sound not as effective to some, a simple mathmatical equation can show us that those who work harder in the gym, have
greater results.

Lets start by taking two people. Person "A" always comes into the gym and walks or
slowly jogs on the treadmill for 30min., so that they can maintain their fat burning
zone. Person "B" however, uses their 30min. to work very hard and push into their
anaerobic training zone. They might just work as hard as they can for 30min. or they
might use a protocol of intervals where they are alternating one hard minute with one
easier minute.

So, we will say that hypothetically, person "A" is working at a total work rate of 8
calories per minute. For 30min. they are burning 240 calroies and lets say that 80% of those calories came from fat storage. That would be 192 calories.

Person "B" is working a lot harder. They are working at a work rate of 15 calories per minute. So, for 30min., they are burning 450 calories (nearly double what person "A" is burning). However, beacuse they are working at a higher work ratem, burning more overal calories, and working anaerobically, they might only be burning 60% of their calories from fat storage. But, beacause they have burned so many calories overal, even though the percentage of fat oxidation has gone down, they are still burning 270 calories from fat (technically) or 60% of 450 total caloric expenditure. Sounds great right!!

The reason I said "technically" about was because in reality, we don't know. The amount of fat that you burn is also going to be dependant on what is in your body at the time (ie the amount of glucose in the blood). So, if you just had a meal prior to your cardio training session, your body is going to have a more readily available source of energy (in the form of glucose) and it will easily take advantage of that.

Worrying about how much fat you have burned during a cardio session is silly. It is like worrying about how much muscle you built duing a weight lifting workout (we all know that we don't build anything in the gym. We tear down). At the end of the day, the main thing is "did you burn more than you took in? Are you in a negative
calorie balance?" Working harder during your workout and monitoring your diet are the best ways to positively effect your metabolism and get down to your desired body fat level.