Is the Fat-Burning Zone a Big Myth?

Want to burn off your body's extra fat? Then get out of the fat-burning zone. Working out in that low-intensity zone—designated as "fat burning" on machines at gyms everywhere—won't automatically drain your body's fat stores. In fact, when it comes to losing weight, the fat-burning zone does far less for you than any other on the machine.

So why does everyone think it's the place to be when you want to trim the excess off your thighs, butt, love handles and other trouble spots?

There's truth to the fact that when you work out at lower intensities, the calories you burn contain a greater amount of fat than carbohydrates.

The higher you go in intensity, the greater percentage of carbs you burn. "But it doesn't mean that your body is sucking fat from adipose tissue and you're getting smaller," says nutrition consultant Jenna Bell, Ph.D., RD, co-author of Energy to Burn.

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When your body uses fat for fuel, it plucks fats from your bloodstream and from little fats stored in your muscles (intramuscular triglycerides), Bell explains. Those fats are replenished from both your fat stores and the fat you eat, not exclusively from your trouble areas. In other words, it's not instant liposuction. "It's like using a debit card," says Bell. "An expenditure does come from your account, but you didn't go to your bank at the time of your purchase."

And when it comes to losing weight, it's not what you're burning that counts; it's how much. If you burn 150 calories in a 30-minute low-intensity workout, and 80 percent of them come from fat, you've still only burned 150 calories. But if you push the intensity and burn 250 calories in 30 minutes, a smaller percentage are from fat, but you've burned 100 more calories. And that's what gets you closer to fitting into those jeans that looked so great on you last year.  

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Who Should Go Low?

Low-intensity workouts still have their place. That's where endurance athletes do their base training, and where just-off-the-couch athletes should start training. The fat-burning zone helps athletes' bodies learn to work out for longer periods of time without undue wear and tear and it lays the groundwork for a ramp up in training.  

Workouts at the very edge of that zone—right where the body switches from burning a mixture of fat and carbs to burning only carbs—are also smart for the endurance athlete. When you move into carb-burning, "you're nearing the point where your intensity will increase to a level where you'll have to lessen your workout duration," Bell says. "But repeatedly getting close to that threshold teaches your body over time to move that line higher, so you can burn a mixture of fuels at faster paces and ultimately go longer."

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What to Do at the Gym

Low-intensity workouts have their place in training plans for certain athletes. But if weight loss is what you want, you'll burn more calories in less time by focusing less on burning fat and more on burning calories. That means working out at a higher intensity, as long as your body can handle it (but not so high that you feel exhausted after five minutes.)

Try this to torch more calories, and add some fun to your gym workout: A new-to-you class can help you not only kick up the intensity; it may keep you going back for more.  

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About the Author

Marty Munson is a USAT Level 1 triathlon coach. Her writing has appeared in Health, Prevention, Marie Claire, Shape.com and RealAge.com. Find more triathlon tips and strategies from her and other experts in the field at trieverything.wordpress.com.

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