Reading 28
Will pumping iron pare the pounds?
Books, magazines and trainers say weightlifting is a great way to slim down, but the experts disagree.
By Martica Heaner
The New York Times
August 2, 2005
Barbara Woodworth, 35, a social worker in Seattle, wanted to drop 40 pounds. Alisa Rivera, 39, a
college adviser at the University of California, Los Angeles, also wanted to lose weight. She also wanted
to build long, lean muscle. So the two women routinely began to lift weights.
But like many of the other 36 million women nationwide who each year pick up dumbbells hoping to lose
pounds or develop a sculptured body, both Woodworth and Rivera ended up disappointed because the
strategy is not as simple -- or as effective -- as it sounds.
Personal trainers, fitness instructors, magazines and books have sold a double-barreled promise that
any strength training builds muscle, and that having more muscle dramatically speeds metabolism,
increasing the calories a person burns while at rest. With all that extra calorie burning, the story goes,
excess weight comes off effortlessly.
The story is wrong in two ways, researchers say. First, muscle is not such an amazing calorie burner.
"Even if weight training increases muscle and metabolism, there is little evidence showing that it is
enough to cause weight loss," says Joseph Donnelly, director of the Energy Balance Laboratory at the
University of Kansas, who has extensively reviewed studies on the link between resistance training and
weight loss.
And second, many who try weight training -- especially women -- fail to do what it actually takes to build
more muscle. They lift too light a weight, or they neglect to progress to heavier weights as they grow
stronger. And often, women who take up weight lifting also diet. In fact, it is nearly impossible to
increase muscle while cutting calories.
Regular resistance training, done correctly, has many benefits. It can prevent some of the muscle loss
that occurs with weight loss. It also can lower body-fat levels and even help preserve bone mass. But
the idea that it can magically increase calorie-burning is "a very big stretch," says Edward Melanson, an
assistant professor in the division of endocrinology, diabetes and metabolism at the University of
Colorado Health Sciences Center in Denver.
Claims that resistance training can send metabolism skyrocketing are easy to find. A Google search
using the terms "metabolism" and "weights" produces thousands of Web sites, many of which say that
anyone can lose weight and build muscle through strength training, even doing routines that aren't
particularly strenuous.
Books such as Kathy Smith's Lift Weights to Lose Weight also perpetuate the myth that building
muscle supercharges metabolism and quickly leads to weight loss. In Smart Girls Do Dumbbells, Judith
Sherman-Wolin claims that resistance-training can "melt away those stubborn pounds you've been trying
to lose all your life." And Jorge Cruise's best seller, 8 Minutes in the Morning, advises readers to
forget aerobics or grueling workouts because doing his two strength-building exercises a day "will help
you firm up five pounds of lean muscle within the first few weeks, allowing your body to burn an extra
250 calories per day."
Woodworth of Seattle says, "Practically every fitness book and magazine I ever read said strength
training boosts metabolism so you lose weight easier and faster."
Before taking up weight lifting, she already had lost 15 pounds in about three months by cutting calories
and walking and running for an hour three times a week. With 40 pounds still to shed, she turned to
what she had heard was the magic bullet.
Her trainer advised her to lift weights four times a week, cut her cardiovascular exercise to less than
30 minutes but still keep dieting. After six weeks, she was frustrated to find she had gained two
pounds. That added weight probably wasn't muscle. Decreasing her high-calorie-burning walks and runs
was the more likely culprit. Lifting weights burns few calories -- "at least the way the average
nonathlete does it and certainly the way most women tend to do it, using relatively low weights and few
sets," Donnelly says. The same time spent on an aerobic workout could double the calorie burn.
Once Woodworth increased her time on cardio, she lost the added weight.
Do numbers add up?
Proponents of the theory that weight lifting leads to weight loss argue that it is the long-term effect
of gaining more muscle, which burns more calories at rest, that causes weight loss. Still, that never has
been proven in studies.
Studies show that even women who do what it takes to get stronger develop only two to four pounds of
muscle after six months of progressive lifting. Given that one pound of muscle burns between 7 to 13
calories a day (as determined by studies that measured oxygen and blood flow to tissues), that means
the average boost in metabolism is only 14 to 52 calories a day, says Dympna Gallagher, director of the
body-composition unit at the New York Obesity Research Center in Manhattan.
The effect of weight lifting "on metabolism is minor and certainly not the savior of dieters," says
William Kraemer, a professor of physiology and neurobiology at the University of Connecticut.
When people lift light weights and fail to progressively increase the load, they only increase endurance,
Kraemer says.
After turning "doughy," Rivera of Los Angeles followed a few workouts using 5-pound weights that she
had seen in Glamour and Shape magazines. "After three months, the scale hadn't budged," she says. "I
didn't see much of a difference in muscle tone."
Eventually she realized that light weights were not enough. "When I progressed from a 5-pound
dumbbell and began to lift heavier, my arms and butt got firmer within three weeks, although I still did
not lose weight," she says.
For those looking to build a more sculptured body, dieting might be counterproductive. "To create new
muscle tissue you need to eat enough, not cut calories, to fuel the process," says Karen Reznik Dolins,
the director of nutrition at Altheus, a sports center in Rye, N.Y.
Shannan Catlett, a fashion sales executive in Manhattan, says lifting heavy weights helped tone her
slimmer body. After she lost 50 pounds by using the elliptical machine and treadmill and by following a
healthier diet, she improved her muscle definition with weights.
"I never lost weight from strength training, but my butt got smaller and I got stronger and firmer all
over," Catlett, 41, says. "I still have to make sure that I'm always fit in regular cardio to maintain my
weight."