Fast paced weight loss

Want to lose weight in a hurry? Research shows that brief and intense (with rests in between) trumps dutiful and steady.

By Selene Yeager / O magazine
Published: April 10, 2009

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While most experts keep telling us we need to exercise longer if we want to lose weight—we're supposed to exercise 60 to 90 minutes a day just to maintain weight loss—a fast-growing body of research indicates that intensity, not duration, is really the missing piece in our fitness puzzle:

Last December, Canadian researchers reported that just two weeks of interval training boosted women's ability to burn fat during exercise by 36 percent.

Levels of human growth hormone—which assists in building muscle and eliminating fat—skyrocketed 530 percent in subjects after just 30 seconds of sprinting as fast as they could on a stationary bike, according to a British study.

Australian fitness researchers had 18 women perform 20 minutes of interval training on a stationary bike—eight-second sprints followed by 12 seconds of recovery throughout the workout, three days a week. The women lost an average of five and a half pounds over 15 weeks without dieting, while a similar group performing 40 minutes of moderate cycling three days a week actually gained a pound of fat over the same period. Two of the heavier women who did intervals dropped 18 pounds.

One reason intervals are effective is that they target more of your muscle, says Canadian study author Martin Gibala, PhD, associate professor of kinesiology at McMaster University. The average exerciser uses a lot of slow-twitch (endurance) muscle fibers and way too few fast-twitch (speed and power) fibers. Working more fast-twitch fibers not only gives you firm, shapely muscle tone but also fast-tracks your fitness gains. "Your body thinks, 'Whoa! That was hard work,' and it responds by increasing your ability to use oxygen and burn fat," Gibala says.