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Saturday, June 23, 2012

Weight Loss and the Myth of the "Fat-Burning Zone"

I was reading Bicycling Magazine the other day, and they had an article about metabolism.  It referenced this study which showed that cyclists burned almost 200 extra calories in the 14 hours after a vigorous 45 minute work-out.

These aren't biking calories - these are resting calories!  Free!

I was immediately reminded of the cardio equipment in the gym which advertised a "fat burning zone".  It was always at a lower heart rate, the theory being that at that rate the percentage of energy coming from fat was higher.

This is obviously true... but calories per minute at the lower intensity is also lower!  So if you have a certain amount of time to exercise, you will burn just as much fat at a higher intensity, plus more calories from other energy sources.  As long as you don't increase your intake, you will lose more weight.

Just as an example:
1 hour vigorous cycling = 1000 calories
1 hour light cycling = 700 calories

Both might use 400 calories from fat, but overall the vigorous cycling creates a bigger calorie deficit.  Ultimately, regardless of the source of the calories during exercise, a calorie deficit means weight loss!

There is also the known fact that muscle tissue takes more calories to maintain at rest than other types of tissue, especially fat, resulting in a higher metabolism.  Those vigorous workouts are more likely to build more muscle than the long "fat-burning zone" workouts.

So don't be fooled into going easy to lose weight - going harder, faster, longer is ultimately the way to get the results!  And nicer muscles!  And the glory of kicking someone else's butt!

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